阅读说明：本技术 台面式硅基阻挡杂质带太赫兹探测器及制备方法 (Mesa type silicon-based impurity-blocking band terahertz detector and preparation method thereof ) 是由 陈雨璐 童武林 王兵兵 王晓东 刘文辉 陈栋 于 2020-05-13 设计创作，主要内容包括：本发明提供了一种台面式硅基阻挡杂质带太赫兹探测器及制备方法,包括：负电极部件(4)、衬底部件、吸收层部件(3)、阻挡层部件、金属光栅部件(2)以及正电极部件(1)；所述正电极部件(1)设置于阻挡层部件上方；所述吸收层部件(3)设置于正电极部件(1)下方；所述负电极部件(4)设置于衬底部件下侧；所述金属光栅部件(2)设置于阻挡层部件上方；所述正电极部件(1)包括：正电极接触区构件(101)；所述正电极接触区构件(101)设置于正电极部件(1)的下部。本发明基于亚波长金属光栅的等离激元共振效应,利用金属等离激元的近场局域特性,当降低吸收层的厚度时,保持器件吸收层的有效吸收效率。(The invention provides a mesa silicon-based impurity band blocking terahertz detector and a preparation method thereof, wherein the mesa silicon-based impurity band blocking terahertz detector comprises the following steps: a negative electrode part (4), a substrate part, an absorption layer part (3), a barrier layer part, a metal grating part (2), and a positive electrode part (1); the positive electrode part (1) is arranged above the barrier part; the absorption layer component (3) is arranged below the positive electrode component (1); the negative electrode part (4) is arranged on the lower side of the substrate part; the metal grating part (2) is arranged above the barrier layer part; the positive electrode component (1) includes: a positive electrode contact region member (101); the positive electrode contact region member (101) is disposed at a lower portion of the positive electrode part (1). The invention is based on the plasmon resonance effect of the sub-wavelength metal grating, utilizes the near-field local characteristic of the metal plasmon, and maintains the effective absorption efficiency of the absorption layer of the device when the thickness of the absorption layer is reduced.)

1. The utility model provides a mesa formula silica-based impurity band terahertz detector that blocks, its characterized in that includes: a negative electrode part (4), a substrate part, an absorption layer part (3), a barrier layer part, a metal grating part (2), and a positive electrode part (1);

the positive electrode part (1) is arranged above the barrier part;

the absorption layer component (3) is arranged below the positive electrode component (1);

the negative electrode part (4) is arranged on the lower side of the substrate part;

the metal grating part (2) is arranged above the barrier layer part;

the positive electrode component (1) includes: a positive electrode contact region member (101);

the positive electrode contact region member (101) is disposed at a lower portion of the positive electrode part (1).

2. The mesa-type silicon-based blocking impurity band terahertz detector according to claim 1, wherein the absorption layer component (3) adopts a silicon-doped phosphorus absorption layer.

3. The mesa-type silicon-based impurity band terahertz detector according to claim 1, wherein the barrier layer component is a silicon barrier layer component;

the resistance of the silicon barrier layer component is greater than a set threshold.

4. The mesa-type silicon-based impurity band terahertz detector according to claim 1, wherein the substrate component is a silicon substrate;

the conductance value of the silicon substrate is greater than a set threshold value.

5. The mesa-type silicon-based blocking impurity band terahertz detector according to claim 1, wherein the metal grating part (2) comprises: a metal grating;

the period of the metal grating is 8-32 μm.

6. The mesa-type silicon-based impurity band terahertz detector according to claim 5, wherein the thickness of the metal grating is 2-7 μm;

the duty cycle of the metal grating is 1/4-3/4.

7. The mesa-type silicon-based blocking impurity band terahertz detector according to claim 1, wherein the positive electrode contact region member (101) is formed by phosphorus ion implantation.

8. A preparation method of a mesa silicon-based impurity band blocking terahertz detector is characterized by comprising the following steps:

step S1: on and along a silicon substrate<100>The crystal orientation is doped with phosphorus ions to grow an absorption layer, the thickness is 3-10 μm, and the doping concentration is 1 × 1017-1 × 1018cm^-3；

Step S2: growing a barrier layer on the absorption layer doped with phosphorus ions along the <100> crystal orientation of the absorption layer, wherein the thickness of the barrier layer is 1-6 mu m;

step S3: thinning and polishing the lower side of the silicon substrate, and depositing a metal layer Ti/Al/Ni/Au on the lower side of the high-conductivity silicon-based substrate;

step S4: annealing in nitrogen atmosphere, and thickening the electrode to form a negative electrode;

step S5: photoetching and depositing metal Ni/Au to form a photoetching mark;

step S6: photoetching to form a mask window required by an ion implantation area;

step S7: forming a positive electrode contact area on the upper surface of the barrier layer by ion implantation;

step S8: nitrogen atmosphere rapid thermal annealing is carried out to repair damaged crystal lattice during ion implantation and activate implanted impurity ions;

step S9: depositing a positive electrode metal layer Ti/Al/Ni/Au, annealing and thickening to form a positive electrode;

step S10: photoetching a mask window required by the metal grating with the periodic structure above the barrier layer and on one side of the positive electrode;

step S11: depositing a Ti/Al metal layer to form a metal grating;

step S12: grinding wheel scribing, gold wire ball bonding and routing and packaging.

9. The method for preparing the mesa-type silicon-based blocking impurity band terahertz detector according to claim 8, wherein the step S10 comprises:

step S10.1: and forming a mask window by adopting negative photoresist KMPR1010 to prepare the metal grating.

10. The method for preparing the mesa-type silicon-based blocking impurity band terahertz detector according to claim 8, wherein the step S11 comprises:

step S11.1: and depositing a Ti/Al metal layer by adopting an electron beam evaporation deposition mode to form the metal grating.

Technical Field

The invention relates to the technical field of terahertz detection, in particular to a mesa silicon-based impurity band blocking terahertz detector and a preparation method thereof, and particularly relates to a mesa silicon-doped phosphorus impurity band blocking terahertz detector integrated with a sub-wavelength metal grating and a preparation method thereof.

Background

The very-long-wave infrared to terahertz waveband photoelectric detection technology is greatly concerned by researchers at home and abroad due to the application of the technology in the fields of national security, astronomical observation, human body security inspection, nondestructive inspection and the like. The silicon-based impurity band blocking detector works in a low-temperature environment below 10K, can effectively detect radiation of a very long wave infrared band to a terahertz band within a band range of 5-40 mu m, and has wide application prospect in the fields of civil use, military use and aerospace. The silicon-based impurity blocking band detector mainly comprises two device structures and preparation processes: one is a planar structure and a fabrication process, and the other is a mesa structure and a fabrication process. The planar silicon-based impurity band blocking detector usually adopts ion implantation to form an absorption layer, but the ion implantation can cause material damage and generate a large number of defects to form a composite center, the dark current of the manufactured detector is large, meanwhile, the depth of the ion implantation is usually less than 1 mu m, and a thicker absorption layer is difficult to form, so that the response rate to incident very long wavelength infrared-terahertz radiation is low. In order to solve the problems of the planar detector, researchers improve the planar detector and develop a mesa detector. The mesa-type detector is usually formed by sequentially epitaxially growing an absorption layer and a barrier layer on a high-conductivity substrate, wherein a positive electrode is disposed on the top of the barrier layer, and a negative electrode is disposed on the bottom of the high-conductivity substrate. The mesa silicon-based impurity blocking band detector is convenient for adjusting the thickness and the doping concentration of an absorption layer, and has the defects that the mesa silicon-based impurity blocking band detector is limited by the limitations of the preparation process level of a device, the doping amount of materials and the thickness of the device, and the mesa silicon-based detector still has the problems of low photoelectric response, large dark current and the like. Moreover, the response of the international existing silicon-based impurity band blocking detector is mainly concentrated on a very-long-wave infrared band, and the response performance of the existing silicon-based impurity band blocking detector on a terahertz band above 30 microns is poor.

Patent document CN110784251A discloses an apparatus and method relating to antenna arrays. The method can comprise the following steps: transmitting a reference signal from each of a plurality of sub-arrays of an antenna array to one or more remote user terminals, each sub-array comprising a number of radiating elements of the antenna array capable of establishing a backhaul link with a remote communications node. The method may further comprise: a measurement signal is received from one or more remote user terminals, the measurement signal being indicative of one or more characteristics of the received reference signal. The method may further comprise: a first subset of the sub-arrays for backhaul communication with a remote communication node and a second subset of the sub-arrays for access communication with one or more remote user terminals are selected based on the received measurement signals, the second subset including one or more of the remaining sub-arrays. The structure and performance of the patent still need to be improved.

Disclosure of Invention

Aiming at the defects in the prior art, the invention aims to provide a mesa silicon-based impurity band blocking terahertz detector and a preparation method thereof.

The invention provides a mesa silicon-based impurity band terahertz blocking detector which is characterized by comprising the following components: a negative electrode part 4, a high-conductivity silicon substrate part, an absorption layer part 3, a barrier layer part, a metal grating part 2, and a positive electrode part 1; the positive electrode component 1 is arranged above the barrier component; the absorption layer member 3 is disposed below the positive electrode member 1; the negative electrode part 4 is arranged on the lower side of the substrate part; the metal grating part 2 is arranged above the barrier layer part; the positive electrode part 1 includes: positive electrode contact region member 101; the positive electrode contact region member 101 is disposed at the lower portion of the positive electrode part 1.

Preferably, the absorption layer component 3 adopts a silicon-doped phosphorus absorption layer.

Preferably, the barrier layer component is a silicon barrier layer component; the resistance of the silicon barrier layer component is greater than a set threshold.

Preferably, the substrate component adopts a silicon substrate; the conductance value of the silicon substrate is greater than a set threshold value.

Preferably, the metal grating member 2 includes: a metal grating; the period of the metal grating is 8-32 μm.

Preferably, the thickness of the metal grating is 2-7 μm; the duty cycle of the metal grating is 1/4-3/4.

Preferably, the positive electrode contact area member 101 is formed using phosphorus ion implantation.

The invention provides a preparation method of a mesa silicon-based impurity band blocking terahertz detector, which comprises the following steps: step S1: doping phosphorus ions along the <100> crystal orientation of a silicon substrate on a high-conductivity silicon substrate to grow an absorption layer, wherein the thickness is 3-10 mu m, and the doping concentration is 1 x 1017-1 x 1018 cm-3; step S2: on the absorption layer with high doped phosphorus ions, a barrier layer is grown along the <100> crystal orientation of the absorption layer, the thickness is 1-6 μm, and no ions are intentionally doped; step S3: thinning and polishing the lower side of the high-conductivity silicon substrate, and depositing a metal layer Ti/Al/Ni/Au on the lower side of the high-conductivity silicon substrate; step S4: annealing in nitrogen atmosphere, and thickening the electrode to form a negative electrode; step S5: photoetching and depositing metal Ni/Au to form a photoetching mark; step S6: photoetching to form a mask window required by an ion implantation area; step S7: forming a positive electrode contact area on the upper surface of the barrier layer by ion implantation; step S8: performing rapid thermal annealing (RTP) in nitrogen atmosphere to repair damaged crystal lattice during ion implantation and activate implanted impurity ions; step S9: depositing a positive electrode metal layer Ti/Al/Ni/Au, annealing and thickening to form a positive electrode; step S10: photoetching a mask window required by the metal grating with the periodic structure above the barrier layer and on one side of the positive electrode; step S11: depositing a Ti/Al metal layer to form a metal grating; step S12: grinding wheel scribing, gold wire ball bonding and routing and packaging.

Preferably, the step S10 includes: step S10.1: and forming a mask window by adopting negative photoresist KMPR1010 to prepare the metal grating.

Preferably, the step S11 includes: step S11.1: and depositing a Ti/Al metal layer by adopting an electron beam evaporation deposition mode to form the metal grating.

Compared with the prior art, the invention has the following beneficial effects:

1. the invention is based on the plasmon resonance effect of the sub-wavelength metal grating, utilizes the near-field local characteristic of the metal plasmon, and maintains the effective absorption efficiency of the absorption layer of the device when the thickness of the absorption layer is reduced;

2. in the invention, the thickness of the absorption layer is reduced, which is equivalent to the reduction of the volume of the absorption layer of a device, and the defects and impurities related to dark current are reduced, so that the dark current of the device is reduced, and the signal-to-noise ratio of photoelectric response of a detector is improved;

3. according to the invention, the plasmon resonance wavelength is regulated and controlled by changing the periodic structure parameters of the metal grating, so that the selective enhancement and absorption of the detector in a wide spectrum range from very-long-wave infrared to terahertz waveband are realized, the waveband is adjustable, and the photoelectric response performance of the detector to the waveband is further improved.

Drawings

Other features, objects and advantages of the invention will become more apparent upon reading of the detailed description of non-limiting embodiments with reference to the following drawings:

fig. 1 is a schematic structural diagram of a mesa-type silicon-based impurity band terahertz detector integrated with a metal grating in an embodiment of the present invention.

Fig. 2 is a schematic structural diagram of a metal grating in a mesa-type silicon-based impurity band terahertz detector integrated with the metal grating in the embodiment of the present invention.

Fig. 3 is a schematic diagram of absorption lines of devices with different metal grating periods in the embodiment of the present invention.

Fig. 4 is a schematic diagram illustrating the relationship between the periods of different metal gratings and the variation of the peak absorption rate and the peak wavelength in the embodiment of the present invention.

Fig. 5 is a schematic diagram of optical field distribution of a device structure under different metal grating periods and with a fixed metal grating thickness and duty ratio in the embodiment of the present invention.

FIG. 6 is a schematic diagram of device absorption lines at different thicknesses of metal gratings in an embodiment of the present invention.

FIG. 7 is a diagram illustrating the relationship between the thickness of different metal gratings and the variation of the peak absorption rate and the peak wavelength according to an embodiment of the present invention.

Fig. 8 is a schematic diagram of optical field distribution of a device structure with a fixed metal grating period and duty ratio and different metal grating thicknesses in the embodiment of the present invention.

FIG. 9 is a schematic diagram of absorption lines of devices at different duty ratios of metal gratings according to an embodiment of the present invention.

Fig. 10 is a schematic diagram illustrating the relationship between the duty cycle of different metal gratings and the variation of the peak absorption rate and the peak wavelength in the embodiment of the present invention.

Fig. 11 is a schematic diagram of optical field distribution of a device structure with a fixed metal grating period and thickness and different metal grating duty cycles in the embodiment of the present invention.

In the figure:

positive electrode member 1 absorbing layer member 3

Positive electrode contact area member 101 negative electrode component 4

Metal grating component 2

Detailed Description

The present invention will be described in detail with reference to specific examples. The following examples will assist those skilled in the art in further understanding the invention, but are not intended to limit the invention in any way. It should be noted that it would be obvious to those skilled in the art that various changes and modifications can be made without departing from the spirit of the invention. All falling within the scope of the present invention.

As shown in fig. 1 to 11, the mesa-type silicon-based terahertz detector provided by the present invention is characterized by comprising: a negative electrode part 4, a high-conductivity silicon substrate part, an absorption layer part 3, a barrier layer part, a metal grating part 2, and a positive electrode part 1; the positive electrode component 1 is arranged above the barrier component; the absorption layer member 3 is disposed below the positive electrode member 1; the negative electrode part 4 is arranged on the lower side of the substrate part; the metal grating part 2 is arranged above the barrier layer part; the positive electrode part 1 includes: positive electrode contact region member 101; the positive electrode contact region member 101 is disposed at the lower portion of the positive electrode part 1.

Preferably, the absorption layer component 3 adopts a silicon-doped phosphorus absorption layer.

Preferably, the barrier layer component is a silicon barrier layer component; the resistance of the silicon barrier layer component is greater than a set threshold.

Preferably, the substrate component adopts a silicon substrate; the conductance value of the silicon substrate is greater than a set threshold value.

Preferably, the metal grating member 2 includes: a metal grating; the period of the metal grating is 8-32 μm.

Preferably, the thickness of the metal grating is 2-7 μm; the duty cycle of the metal grating is 1/4-3/4.

Preferably, the positive electrode contact area member 101 is formed using phosphorus ion implantation.

In one embodiment, the integrated metal grating mesa silicon-based impurity blocking band detector comprises a negative electrode, a high-conductivity silicon substrate, a silicon-doped phosphorus absorption layer, a high-resistance silicon blocking layer, a metal grating, a positive electrode contact area and a positive electrode from bottom to top in sequence. Wherein, the positive electrode is positioned above the barrier layer, and the negative electrode is positioned at the lower side of the high-conductivity substrate; the metal grating is arranged above the barrier layer and on one side of the positive electrode.

In a further improvement, the substrate is a high-conductivity silicon substrate doped with arsenic.

In a further improvement, the positive electrode contact area is formed by phosphorus ion implantation.

In a further improvement, the absorption layer is doped with phosphorus ions.

Preferably, the metal grating is a Ti/Al metal layer, the period is 8-32 μm, the thickness is 2-7 μm, and the duty ratio is 1/4-3/4.

The invention provides a preparation method of a mesa silicon-based impurity band blocking terahertz detector, which comprises the following steps: step S1: doping phosphorus ions along the <100> crystal orientation of a silicon substrate on a high-conductivity silicon substrate to grow an absorption layer, wherein the thickness is 3-10 mu m, and the doping concentration is 1 x 1017-1 x 1018 cm-3; step S2: on the absorption layer with high doped phosphorus ions, a barrier layer is grown along the <100> crystal orientation of the absorption layer, the thickness is 1-6 μm, and no ions are intentionally doped; step S3: thinning and polishing the lower side of the high-conductivity silicon substrate, and depositing a metal layer Ti/Al/Ni/Au on the lower side of the high-conductivity silicon substrate; step S4: annealing in nitrogen atmosphere, and thickening the electrode to form a negative electrode; step S5: photoetching and depositing metal Ni/Au to form a photoetching mark; step S6: photoetching to form a mask window required by an ion implantation area; step S7: forming a positive electrode contact area on the upper surface of the barrier layer by ion implantation; step S8: nitrogen atmosphere rapid thermal annealing (RTP), repairing damaged crystal lattice during ion implantation, and activating implanted impurity ions; step S9: depositing a positive electrode metal layer Ti/Al/Ni/Au, annealing and thickening to form a positive electrode; step S10: photoetching a mask window required by the metal grating with the periodic structure above the barrier layer and on one side of the positive electrode; step S11: depositing a Ti/Al metal layer to form a metal grating; step S12: grinding wheel scribing, gold wire ball bonding and routing and packaging.

Preferably, the step S10 includes: step S10.1: and forming a mask window by adopting negative photoresist KMPR1010 to prepare the metal grating.

Preferably, the step S11 includes: step S11.1: and depositing a Ti/Al metal layer by adopting an electron beam evaporation deposition mode to form the metal grating.

In one embodiment, the metal grating integrated mesa type silicon-based impurity band terahertz detector has a mesa structure. A silicon-phosphorus-doped absorption layer and a barrier layer are sequentially arranged on the high-conductivity silicon substrate, and a negative electrode is arranged below the high-conductivity silicon substrate; the upper surface area of the barrier layer is a positive electrode contact layer, a positive electrode and a metal grating are arranged above the barrier layer, and the positive electrode is adjacent to the metal grating.

A simple preparation method of a mesa type silicon-based impurity blocking band terahertz detector integrated with a metal grating comprises the following steps:

step S1: as shown in FIG. 1, a phosphorus ion doped absorption layer with a thickness of 3-10 μm and a doping concentration of 1 × 1017-1 × 1018cm-3 is grown on a high-conductivity silicon substrate along a <100> crystal orientation of the silicon substrate;

step S2: growing a barrier layer on the silicon-doped phosphorus absorption layer along the <100> crystal orientation of the absorption layer, wherein the thickness of the barrier layer is 1-6 mu m, and no ions are intentionally doped;

step S3: thinning and polishing the lower side of the high-conductivity silicon substrate, and depositing a metal layer Ti/Al/Ni/Au on the lower side of the high-conductivity silicon substrate;

step S4: annealing in nitrogen atmosphere, and thickening the electrode to form a negative electrode;

step S5: photoetching and depositing metal Ni/Au to form a photoetching mark;

step S6: photoetching to form a mask window required by an ion implantation area;

step S7: forming a positive electrode contact area on the upper surface of the barrier layer by ion implantation;

step S8: nitrogen atmosphere rapid thermal annealing (RTP), repairing damaged crystal lattice during ion implantation, and activating implanted doped ions;

step S9: depositing a positive electrode metal layer Ti/Al/Ni/Au, annealing and thickening to form a positive electrode;

step S10: photoetching and forming a mask window required by the metal grating above the barrier layer and on one side of the positive electrode;

step S11: and depositing a Ti/Al metal layer to form the metal grating.

Step S12: grinding wheel scribing, gold wire ball bonding and routing and packaging.

The preparation process proposed by the present invention is explained in more detail below:

firstly, cleaning a high-conductivity silicon substrate: firstly, respectively carrying out ultrasonic treatment on acetone and isopropanol for 15 minutes, and washing with deionized water to remove organic pollutants; then sequentially using NH4 OH: H2O ═ 1: 10 for 15 minutes, and the volume ratio is HCl: H2O ═ 1: soaking the solution of 10 for 3 minutes, washing with deionized water, and drying with nitrogen to remove surface oxide particle pollutants;

secondly, growing an absorption layer by chemical vapor deposition: epitaxially growing a silicon-doped phosphorus absorption layer on a high-conductivity silicon substrate by adopting a chemical vapor deposition process, wherein the growth thickness is 3-10 mu m, and the doping concentration is 1 x 1017-1 x 1018 cm-3;

thirdly, growing a barrier layer by chemical vapor deposition: epitaxially growing an intrinsic silicon barrier layer on the silicon-doped phosphorus absorption layer by adopting a chemical vapor deposition process, wherein the growth thickness is 1-6 mu m, and no ions are intentionally doped;

step four, thinning and polishing the high-conductivity silicon substrate: thinning and removing the lower surface of the high-conductivity silicon substrate by 20-30 microns by using a thinning machine, and then Polishing the lower side surface of the high-conductivity silicon substrate by using Chemical Mechanical Polishing (CMP) to enable the roughness of the lower side surface of the high-conductivity silicon substrate to be less than 50 nm;

fifthly, evaporating a negative electrode: evaporating a negative electrode by adopting an electron beam evaporation process, and evaporating Ti, Al, Ni and Au in sequence from bottom to top, wherein the evaporation thicknesses are respectively 20nm, 120nm, 20nm and 100 nm;

sixthly, annealing the negative electrode: adopting an annealing process, wherein the annealing temperature is 450 ℃ and the annealing temperature is kept for 30 minutes in a nitrogen atmosphere, so that the electrode forms good ohmic contact;

step seven, thickening the negative electrode: evaporating a negative electrode by adopting an electron beam evaporation process, and evaporating Ni and Au on the surface of the high-conductivity silicon substrate from bottom to top in sequence, wherein the evaporation thicknesses are respectively 20nm and 260nm, so as to finish the preparation of the negative electrode;

eighth step, photoetching for the first time: spin-coating positive photoresist AZ5214 with the thickness of 1.2 μm on the upper surface of the intrinsic silicon barrier layer, and exposing and developing to form a mask window of a photoetching mark region;

ninth, removing photoresist by plasma: further removing the residual photoresist basement membrane after exposure and development by adopting an oxygen plasma photoresist removing process;

step ten, evaporating and plating a photoetching mark: preparing a photoetching mark by adopting an electron beam evaporation process, evaporating the photoetching mark on the surface of the intrinsic silicon barrier layer, wherein the vacuum degree is 5 multiplied by 10 < -4 > Pa, and sequentially evaporating Ni and Au metal films with the thicknesses of 20nm and 180nm respectively;

the tenth step, stripping: stripping with acetone, soaking at room temperature for 2 hours, ultrasonically cleaning for 10 minutes, ultrasonically cleaning with isopropanol for 5 minutes, flushing with deionized water, and drying with nitrogen;

a twelfth step, photoetching for the second time: throwing positive glue AZ5214 with the thickness of 1.8 mu m on the surface of the intrinsic silicon barrier layer, exposing and developing to form an ion implantation area mask window;

step ten, removing photoresist by plasma: further removing the residual photoresist basement membrane after exposure and development by adopting an oxygen plasma photoresist removing process;

fourteenth, ion implantation: on the upper surface of the barrier layer, adopting an ion implantation process, wherein the implanted ions are phosphorus ions, the implantation energy is 20-50 keV, and the implantation dosage is 1 × 1014 cm-2-7 × 1014 cm-2;

fifteenth step, rapid thermal annealing: in a nitrogen atmosphere, activating injected ions and repairing crystal lattice damage by adopting a rapid thermal annealing process, wherein the annealing temperature is 900-1000 ℃, the annealing temperature holding time is 5-20 seconds, and a positive electrode contact area is formed;

sixteenth step, photoetching for the third time: leveling positive glue AZ5214 with the thickness of 1.2 mu m on the surface of the barrier layer, and exposing and developing to form a mask window required by an evaporation positive electrode;

seventeenth step, evaporating a positive electrode: evaporating a positive electrode by adopting an electron beam evaporation process, and evaporating Ti, Al, Ni and Au on the surface of the barrier layer from bottom to top in sequence, wherein the evaporation thicknesses are respectively 20nm, 120nm, 20nm and 100 nm;

eighteenth, stripping: stripping by using acetone, soaking for 2 hours at room temperature, ultrasonically cleaning for 30 minutes, ultrasonically cleaning for 5 minutes by using isopropanol, and washing by using deionized water to obtain a positive electrode evaporation area;

step nineteenth, annealing the positive electrode: adopting an annealing process, wherein the annealing temperature is 450 ℃ and the annealing temperature is kept for 30 minutes in a nitrogen atmosphere, so that the electrode forms good ohmic contact;

twentieth step, fourth photoetching: leveling positive glue AZ5214 with the thickness of 1.2 mu m on the surface of the barrier layer, and exposing and developing to form a mask window required by thickening the evaporated positive electrode;

twenty-first step, removing photoresist by plasma: removing the residual photoresist basement membrane after clean exposure and development by adopting an oxygen plasma photoresist removing process;

twenty two steps, thickening the positive electrode: evaporating a negative electrode by adopting an electron beam evaporation process, and evaporating Ni and Au in sequence from bottom to top, wherein the evaporation thicknesses are respectively 20nm and 260nm, so as to finish the preparation of a positive electrode;

and a twenty-third step, stripping: stripping with acetone, soaking at room temperature for 2 hours, ultrasonically cleaning for 20 minutes, ultrasonically cleaning with isopropanol for 10 minutes, flushing with deionized water, and drying with nitrogen;

twenty-fourth step, fifth lithography: spin-coating negative photoresist KMPR1010 with the thickness of 10 mu m on the surface of the barrier layer, and exposing and developing to form a mask window required by evaporation of the metal grating structure;

twenty-fifth step, removing photoresist by plasma: removing the residual photoresist basement membrane after clean exposure and development by adopting an oxygen plasma photoresist removing process;

and twenty-sixth step, metal grating is evaporated: evaporating metal grating by electron beam evaporation process with vacuum degree of 5 × 10-4Pa and electron beam energy of 100KeV, and sequentially evaporating Ti and Al with thickness of 50nm and 4950nm respectively;

twenty-seventh step, stripping: stripping by adopting N-methylpyrrolidone (NMP), heating in a water bath for 2 hours, ultrasonically cleaning by using isopropanol for 5 minutes, flushing by using deionized water, and drying by using nitrogen;

and twenty-eighth step, packaging: and (3) leading out the positive electrode and the negative electrode of the device by adopting a grinding wheel scribing and gold wire ball bonding process to finish the packaging of the device, thus finishing the whole preparation process of the mesa silicon-based impurity blocking band terahertz detector integrated with the metal grating.

Compared with the traditional silicon-based impurity band blocking detector, the detector provided by the invention has the advantage that the spectral response performance of the detector is remarkably improved. Based on the optical field local area and near field coupling enhancement effect of the metal grating, the thickness of the absorption layer of the detector can be reduced to be below 10 mu m, and the optical response of the device unit is still kept. In addition, the reduction of the thickness of the absorption layer of the detector reduces the volume of the photosensitive element of the device, thereby reducing the dark current and further improving the signal-to-noise ratio (the structure of the device is shown in figure 1). In fig. 2, p denotes a period of the metal grating, w denotes a space between the metal strips, and d denotes a thickness of the metal grating. As shown in fig. 2, the metal grating structure parameters include period (p), thickness (d) and duty cycle (DR), wherein the duty cycle is defined as the ratio w/p of the interval (w) between the metal strips to the period (p). By introducing a metal grating with the period p being 32 μm on the silicon-based blocking impurity band detector, the peak wavelength can be moved from 26.9 μm to 36.53 μm, and the spectral response improvement of the terahertz waveband above 30 μm is realized, as shown in fig. 3 and 4. Fig. 5 shows the optical field distribution at the peak with a fixed grating thickness and different grating periods, which indicates that plasmon causes optical field local resonance below the metal grating, and enhances the absorption efficiency of the absorption layer for incident terahertz waves. Further, compared with the conventional silicon-based blocking impurity band detector, the peak absorption rate of the detector after introducing the metal grating (the structure parameters: p is 8 μm, d is 6 μm, and DR is 1/4) is improved by 87.3%, as shown in fig. 6 and 7. Therefore, the detector realizes the adjustability of selective wavelength resonance enhanced absorption and terahertz waveband spectral response.

Through the analysis and the explanation, the mesa type silicon-based impurity band terahertz blocking detector integrated with the metal grating realizes the improvement of spectral response performance and the adjustability of wave band, thereby proving the effectiveness of the detector.

The invention is based on the plasmon resonance effect of the sub-wavelength metal grating, utilizes the near-field local characteristic of the metal plasmon, and maintains the effective absorption efficiency of the absorption layer of the device when the thickness of the absorption layer is reduced; in the invention, the thickness of the absorption layer is reduced, which is equivalent to the reduction of the volume of the absorption layer of a device, and the defects and impurities related to dark current are reduced, so that the dark current of the device is reduced, and the signal-to-noise ratio of photoelectric response of a detector is improved; according to the invention, the plasmon resonance wavelength is regulated and controlled by changing the periodic structure parameters of the metal grating, so that the selective enhancement and absorption of the detector in a wide spectrum range from very-long-wave infrared to terahertz waveband are realized, the waveband is adjustable, and the photoelectric response performance of the detector to the waveband is further improved.

In the description of the present application, it is to be understood that the terms "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", and the like indicate orientations or positional relationships based on those shown in the drawings, and are only for convenience in describing the present application and simplifying the description, but do not indicate or imply that the referred device or element must have a specific orientation, be constructed in a specific orientation, and be operated, and thus, should not be construed as limiting the present application.

The foregoing description of specific embodiments of the present invention has been presented. It is to be understood that the present invention is not limited to the specific embodiments described above, and that various changes or modifications may be made by one skilled in the art within the scope of the appended claims without departing from the spirit of the invention. The embodiments and features of the embodiments of the present application may be combined with each other arbitrarily without conflict.