阅读说明：本技术 n型氧化物/p型石墨烯异质pn结紫外光电探测器制备方法 (Preparation method of n-type oxide/p-type graphene heterogeneous pn junction ultraviolet photoelectric detector ) 是由 李炳生 王玉杰 王月飞 徐海阳 刘益春 于 2021-08-10 设计创作，主要内容包括：本发明涉及一种n型氧化物/p型石墨烯异质pn结紫外光电探测器及制备方法,包括衬底、n型氧化物,p型石墨烯连续薄膜,聚甲基丙烯酸甲酯(PMMA)保护层、第一接触电极以及第二接触电极,其特征在于：所述n型氧化物位于所述衬底上,所述n型氧化物一端顶部与所述p型石墨烯连续薄膜中间的底部连接,所述p型石墨烯连续薄膜两端的底部与所述衬底连接,所述p型石墨烯连续薄膜顶部覆盖所述聚甲基丙烯酸甲酯(PMMA)保护层,所述p型石墨烯连续薄膜与所述衬底之间设有第一接触电极,所述n型氧化物另一端与第二接触电极连接。(The invention relates to an n-type oxide/p-type graphene heterogeneous pn junction ultraviolet photoelectric detector and a preparation method thereof, wherein the n-type oxide/p-type graphene heterogeneous pn junction ultraviolet photoelectric detector comprises a substrate, an n-type oxide, a p-type graphene continuous film, a polymethyl methacrylate (PMMA) protective layer, a first contact electrode and a second contact electrode, and is characterized in that: the n-type oxide is located on the substrate, the top of one end of the n-type oxide is connected with the bottom of the middle of the p-type graphene continuous film, the bottoms of the two ends of the p-type graphene continuous film are connected with the substrate, the top of the p-type graphene continuous film covers the polymethyl methacrylate (PMMA) protective layer, a first contact electrode is arranged between the p-type graphene continuous film and the substrate, and the other end of the n-type oxide is connected with a second contact electrode.)

1. The utility model provides a pn junction type photoelectric detector based on n type oxide/p type graphite alkene, includes substrate, n type oxide, the continuous film of p type graphite alkene, polymethyl methacrylate (PMMA) protective layer, first contact electrode and second contact electrode which characterized in that: the n-type oxide is located on the substrate, the top of one end of the n-type oxide is connected with the bottom of the middle of the p-type graphene continuous film, the bottoms of the two ends of the p-type graphene continuous film are connected with the substrate, the top of the p-type graphene continuous film covers the polymethyl methacrylate (PMMA) protective layer, a first contact electrode is arranged between the p-type graphene continuous film and the substrate, and the other end of the n-type oxide is connected with a second contact electrode.

2. The n-type oxide/p-type graphene-based pn junction photodetector of claim 1, wherein: the n-type oxide is gallium oxide, zinc oxide or stannic oxide.

3. The n-type oxide/p-type graphene-based pn junction photodetector of claim 1, wherein: the p-type graphene is a nitrogen-doped graphene continuous film.

4. The n-type oxide/p-type graphene-based pn junction photodetector of claim 1, wherein: the substrate is a rigid insulating substrate or a flexible insulating substrate; the rigid substrate includes: quartz glass, sapphire, SiO₂(ii) a The flexible substrate is polyimide, polyethylene terephthalate, polydimethylsiloxane or mica.

5. The n-type oxide/p-type graphene-based pn junction photodetector of claim 1, wherein: the first contact electrode and the second contact electrode are metal contact electrodes or transparent conductive oxide thin film contact electrodes;

the contact metal electrode is a single-layer metal formed by one or more of indium, aluminum, gold, silver, platinum, nickel and titanium or a metal composite layer; the transparent conductive oxide film contact electrode is made of fluorine-doped tin oxide (FTO) or Indium Tin Oxide (ITO).

6. The n-type oxide/p-type graphene-based pn junction photodetector of claim 1, wherein:

when the active region of the photoelectric detector is n-type gallium oxide, the response wave band corresponds to a deep ultraviolet UVC wave band;

or; when the n-type material of the photoelectric detector is zinc oxide and stannic oxide, the corresponding wave band is 340nm and corresponds to the UVB wave band;

the p-type graphene continuous film plays a role in hole transmission, and has no obvious light response to ultraviolet bands.

7. A preparation method of an n-type oxide/p-type graphene heterogeneous pn junction ultraviolet photodetector comprises the following steps:

step 1, preparing an n-type oxide;

step 2, preparing a pn junction;

and 3, preparing the electrode.

8. The method for preparing an n-type oxide/p-type graphene heterogeneous pn junction ultraviolet photodetector as claimed in claim 7, wherein the method comprises the following steps:

the n-type oxide in the step 1 is gallium oxide, zinc oxide or stannic oxide, the gallium oxide is a gallium oxide micron line or a gallium oxide film, and the gallium oxide micron line grows by a hot carbon reduction method; the gallium oxide film grows by magnetron sputtering or MOCVD large-scale equipment;

preparing the gallium oxide microwire: taking the mass ratio of 1: 1, fully grinding the gallium oxide powder and the carbon powder to uniformly mix the gallium oxide powder and the carbon powder; putting a proper amount of the mixed powder into a corundum boat, putting the cleaned substrate right above the powder, putting the corundum boat containing the mixed powder into a quartz tube, then putting the quartz tube into a high-temperature tube furnace for growth, and introducing inert gas serving as carrier gas in the growth process, wherein the flow of the inert gas is 50-200 sccm; the growth pressure is normal pressure, the growth temperature is 1000-; the gallium oxide microwire is monoclinic phase and cylindrical, the length of the microwire is 0.5-2cm, the section width is 3-15 μm, and the section thickness is 3-15 μm.

9. The method for preparing an n-type oxide/p-type graphene heterogeneous pn junction ultraviolet photodetector as claimed in claims 7 to 8, wherein the method comprises the following steps:

in the step 2, after the copper-based p-type nitrogen-doped graphene continuous film is spin-coated by using polymethyl methacrylate (PMMA), the copper-based p-type nitrogen-doped graphene continuous film is placed into chemical etching liquid to completely etch the Cu substrate, the cleaned p-type graphene is combined with the n-type gallium oxide microwire obtained in the step 1, but the polymethyl methacrylate (PMMA) is not removed, and the layer structure formed by the polymethyl methacrylate (PMMA) prevents the graphene from directly contacting with air, so that the stability of the device is enhanced; then drying and adopting a gradient heating method to enable the materials to be in close contact with each other by virtue of Van der Waals force;

the chemical etching liquid in the step 2 is oxidant such as ferric trichloride or ammonium persulfate, and the concentration of the oxidant is 1-10 mol/L;

the drying in the step 2 is carried out in a forced air drying box, and the constant temperature is kept for 10-30min at 20-30 ℃, 40-50 ℃ and 60-70 ℃ respectively, so that bubbles generated by water evaporation in the transfer process are reduced, and the distance between the micron line and the graphene is favorably reduced;

the gradient heating in the step 2 is completed in a constant-temperature heating table, the heating temperature of the constant-temperature heating table is 110-.

10. The method for preparing an n-type oxide/p-type graphene heterogeneous pn junction ultraviolet photodetector as claimed in claims 7 to 9, wherein the method comprises the following steps:

preparing a contact electrode in step 3: and preparing electrodes at two ends of the n-type gallium oxide and the p-type graphene respectively by using methods such as magnetron sputtering, thermal evaporation and the like to obtain the self-powered ultraviolet photoelectric detector of the n-type gallium oxide/p-type graphene heterogeneous pn junction.

Technical Field

The invention relates to the field of semiconductor photoelectric detector preparation, in particular to an n-type oxide/p-type graphene heterogeneous pn junction ultraviolet photoelectric detector and a preparation method thereof.

Background

It is known that the sun is a natural ultraviolet source, and radiates ultraviolet rays with various wavelengths, which are classified into near ultraviolet rays (low frequency, UVA), far ultraviolet rays (intermediate frequency, UVB), and ultra-short ultraviolet rays (high frequency, UVC) according to wave length, and although ultraviolet rays occupy only a small portion of the wavelength of solar radiation, they greatly affect the normal work and life of human beings. Detectors operating in the ultraviolet band are referred to as ultraviolet detectors. The device is a new detection technology, optical signals can be converted into electric signals, and UVA and UVB band detectors can be used for environment monitors, ultraviolet sensors and optical communication; due to the existence of the ozone layer, UVC can be absorbed by the atmosphere, so that the wave band is called as a solar blind wave band, and the detector working in the wave band can be applied to the fields of flame monitoring, missile early warning, ozone cavity monitoring, satellite space communication and the like. Detectors operating in the solar blind area can minimize the probability of false positives even under strong sunlight interference on the earth's surface. Efficient photodetectors must meet five requirements, namely high sensitivity, high signal current to dark current ratio, high spectral selectivity, high response speed and high thermal stability. In addition, the self-powered photoelectric detector can save an external power supply device compared with the traditional detector, can effectively reduce the size of a device, reduce the loss of the device, prolong the service life of the device, even can realize the detection requirements and the like under severe environments (external atmosphere or deep sea detection and the like), and has recently attracted great attention of people.

Up to now, the ultraviolet photoelectric detector of materials such as ZnMgO, AlGaN and the like can be realized through band gap adjustment and alloying processes. However, the alloying process introduces a high defect density, thereby increasing dark current and reducing the performance of the detector. Due to the fact that wide band gap oxide semiconductors such as gallium oxide and zinc oxide have strong self-compensation effect, acceptor solid solubility is low, ionization energy is high and the like, p-type doping is difficult to achieve, and therefore a high-performance oxide homogeneous pn junction type photoelectric detector is difficult to manufacture.

Disclosure of Invention

The invention designs an n-type oxide/p-type graphene heterogeneous pn junction ultraviolet photoelectric detector and a preparation method thereof, and solves the technical problems that p-type doping is difficult to realize due to the fact that wide band gap oxide semiconductors such as gallium oxide and zinc oxide have strong self-compensation effect, low acceptor solid solubility, high ionization energy and the like, and therefore the high-performance oxide homogeneous pn junction photoelectric detector is difficult to prepare.

In order to solve the technical problems, the invention adopts the following scheme:

the utility model provides a based on n type oxide/p type graphite alkene pn knot type photoelectric detector, includes substrate, n type oxide, p type graphite alkene continuous film, polymethyl methacrylate (PMMA) protective layer, first contact electrode and second contact electrode, n type oxide is located on the substrate, n type oxide one end top with the bottom in the middle of the continuous film of p type graphite is connected, the bottom at the continuous film both ends of p type graphite alkene with the substrate is connected, the continuous film top of p type graphite alkene covers polymethyl methacrylate (PMMA) protective layer, the continuous film of p type graphite alkene with be equipped with first contact electrode between the substrate, the n type oxide other end is connected with the second contact electrode.

Preferably, the n-type oxide is gallium oxide, zinc oxide or tin dioxide.

Preferably, the p-type graphene is a nitrogen-doped graphene continuous film.

Preferably, the substrate is a rigid insulating substrate or a flexible insulating substrate; the rigid substrate includes: quartz glass, sapphire, SiO₂(ii) a The flexible substrate is polyimide, polyethylene terephthalate, polydimethylsiloxane or mica.

Preferably, the first contact electrode and the second contact electrode are metal contact electrodes or transparent conductive oxide thin film contact electrodes;

the contact metal electrode is a single-layer metal formed by one or more of indium, aluminum, gold, silver, platinum, nickel and titanium or a metal composite layer; the transparent conductive oxide film contact electrode is made of fluorine-doped tin oxide (FTO) or Indium Tin Oxide (ITO).

Preferably, when the active region of the photodetector is n-type gallium oxide, the response band corresponds to the deep ultraviolet UVC band;

or; when the n-type material of the photoelectric detector is zinc oxide and stannic oxide, the corresponding wave band is 340nm and corresponds to the UVB wave band;

the p-type graphene continuous film plays a role in hole transmission, and has no obvious light response to ultraviolet bands.

A preparation method of an n-type oxide/p-type graphene heterogeneous pn junction ultraviolet photodetector comprises the following steps:

step 1, preparing an n-type oxide;

step 2, preparing a pn junction;

and 3, preparing the electrode.

Preferably, the n-type oxide in step 1 is gallium oxide, zinc oxide or tin dioxide, the gallium oxide is a gallium oxide microwire or a gallium oxide thin film, and the gallium oxide microwire is grown by a thermal carbon reduction method; the gallium oxide film grows by magnetron sputtering or MOCVD large-scale equipment;

preparing the gallium oxide microwire: taking the mass ratio of 1: 1, fully grinding the gallium oxide powder and the carbon powder to uniformly mix the gallium oxide powder and the carbon powder; putting a proper amount of the mixed powder into a corundum boat, putting the cleaned substrate right above the powder, putting the corundum boat containing the mixed powder into a quartz tube, then putting the quartz tube into a high-temperature tube furnace for growth, and introducing inert gas serving as carrier gas in the growth process, wherein the flow of the inert gas is 50-200 sccm; the growth pressure is normal pressure, the growth temperature is 1000-; the gallium oxide microwire is monoclinic phase and cylindrical, the length of the microwire is 0.5-2cm, the section width is 3-15 μm, and the section thickness is 3-15 μm.

Preferably, in the step 2, after the copper-based p-type nitrogen-doped graphene continuous film is spin-coated by using polymethyl methacrylate (PMMA), the copper-based p-type nitrogen-doped graphene continuous film is placed into chemical etching liquid to completely etch the Cu substrate, the cleaned p-type graphene is combined with the n-type gallium oxide microwire obtained in the step 1, but the polymethyl methacrylate (PMMA) is not removed, and the layer structure formed by the polymethyl methacrylate (PMMA) prevents the graphene from directly contacting with air, so that the stability of the device is enhanced; then drying and adopting a gradient heating method to enable the materials to be in close contact with each other by virtue of Van der Waals force;

the chemical etching liquid in the step 2 is oxidant such as ferric trichloride or ammonium persulfate, and the concentration of the oxidant is 1-10 mol/L;

the drying in the step 2 is carried out in a forced air drying box, and the constant temperature is kept for 10-30min at 20-30 ℃, 40-50 ℃ and 60-70 ℃ respectively, so that bubbles generated by water evaporation in the transfer process are reduced, and the distance between the micron line and the graphene is favorably reduced;

the gradient heating in the step 2 is completed in a constant-temperature heating table, the heating temperature of the constant-temperature heating table is 110-.

Preferably, the preparation of the contact electrode in step 3: and preparing electrodes at two ends of the n-type gallium oxide and the p-type graphene respectively by using methods such as magnetron sputtering, thermal evaporation and the like to obtain the self-powered ultraviolet photoelectric detector of the n-type gallium oxide/p-type graphene heterogeneous pn junction.

The n-type oxide/p-type graphene heterogeneous pn junction ultraviolet photoelectric detector and the preparation method have the following beneficial effects:

(1) the graphene has high transmittance and does not respond to any wave band, and the active region of the graphene is provided by oxide, so that the cut-off edge of the detector is in an ultraviolet wave band, the active region of the device is ensured to be in a solar blind region, and the detection efficiency of the photoelectric detector is improved. The p-type graphene and the n-type gallium oxide are combined to form a space charge region, when the device is illuminated, a large number of photo-generated electron-hole pairs can be generated, and due to the existence of a built-in electric field, the electron-hole pairs can be effectively separated under the condition that an external power supply is not applied to the device.

(2) The solar blind ultraviolet photoelectric detector is simple in preparation method, only commercial copper-based p-type graphene needs to be transferred onto gallium oxide, the carrier PMMA does not need to be removed, the transfer step of the graphene is simplified, the use of organic solvents is reduced, the cost is reduced, meanwhile, the situation that the performance of the device is reduced due to residual organic matters can be avoided, more importantly, the PMMA can have a certain supporting and protecting effect on the graphene, the graphene is prevented from being in direct contact with air, and therefore the stability and reliability of the device are improved.

(3) The ultraviolet photoelectric detector of the n-type gallium oxide/p-type graphene heterogeneous pn junction prepared by the invention can work under the condition of no external power supply, the volume of the device can be reduced, the power consumption is reduced, and the service life of the device is prolonged; the device can realize the self-powered detection of solar blind wave bands, can meet the detection requirements in severe environments, and can realize space or deep sea detection.

Drawings

FIG. 1 is a schematic structural diagram of an n-type gallium oxide microwire/p-type graphene heterogeneous pn junction solar blind ultraviolet detector of the present invention;

FIG. 2 is a graph of the IV curve of the n-type gallium oxide/p-type graphene pn junction of the present invention under dark and 235nm illumination;

FIG. 3 is a graph of It cycle curves of a gallium oxide microwire/graphene heterojunction solar blind ultraviolet detector under 0V bias and 235nm illumination in accordance with the present invention;

FIG. 4 is a graph of photoresponse and detectivity of a gallium oxide microwire/graphene heterojunction solar-blind ultraviolet detector under 0V bias voltage;

FIG. 5 is a responsivity curve diagram of a gallium oxide microwire/graphene heterojunction solar-blind ultraviolet detector under different bias voltages.

Description of reference numerals:

1-a substrate; 2-p type graphene continuous film; 3-n-type gallium oxide microwire; 4-a first contact metal electrode; 5-second contact metal electrode.

Detailed Description

The invention is further illustrated below with reference to fig. 1 to 5:

as shown in fig. 1, an n-type oxide/p-type graphene-based pn junction photodetector includes a substrate 1, an n-type gallium oxide microwire 3, a p-type graphene continuous thin film 2, a polymethyl methacrylate (PMMA) protective layer, a first contact metal electrode 4, and a second contact metal electrode 5, wherein the n-type gallium oxide microwire 3 is located on the substrate 1, the top of one end of the n-type gallium oxide microwire 3 is connected with the bottom of the middle of the p-type graphene continuous thin film 2, the bottoms of two ends of the p-type graphene continuous thin film 2 are connected with the substrate 1, the top of the p-type graphene continuous thin film 2 covers the PMMA protective layer, the first contact metal electrode 4 is arranged between the p-type graphene continuous thin film 2 and the substrate 1, and the other end of the p-type graphene continuous thin film 2 is connected with the second contact metal electrode 5.

Example 1;

step 1, preparing the micron line: taking the mass ratio of 1: 1, grinding the high-purity gallium oxide powder and the carbon powder for more than 3 hours to uniformly mix the high-purity gallium oxide powder and the carbon powder; putting a proper amount of the mixed powder into a corundum boat, sequentially cleaning a substrate for ten minutes by using detergent, acetone, alcohol and deionized water, drying the substrate by using high-purity nitrogen after cleaning, placing the substrate right above the powder, putting the corundum boat containing the mixed powder into a quartz tube, then putting the quartz tube into a high-temperature tube furnace for growth, and introducing high-purity argon or nitrogen as carrier gas in the growth process; the growth pressure is normal pressure; the growth temperature is 1070 ℃, and the gallium oxide micron line is obtained after the growth is finished and the natural cooling is carried out to the room temperature.

Step 2, preparation of pn junction: firstly, transferring a single micron line onto a clean quartz glass substrate by using a pair of tweezers, and fixing one end of the single micron line by simply pressing an indium electrode; the method comprises the steps of coating polymethyl methacrylate (PMMA) on the top end of a copper-based p-type nitrogen-doped graphene continuous film in a rotating mode, drying for 1 hour at the temperature of 80 ℃, cutting the copper-doped PMMA into pieces with the size of 5mm multiplied by 5mm, putting the pieces into 1mol/L ferric trichloride solution until copper is completely dissolved, combining the cleaned p-type graphene with n-type gallium oxide microwires, but not removing the polymethyl methacrylate (PMMA), naturally evaporating water until the water is completely evaporated, then putting the combined gallium oxide microwires/graphene/polymethyl methacrylate in a drying box to dry for 30 minutes at the temperature of 20 ℃, 40 ℃ and 60 ℃ respectively, and finally heating for 30 minutes at the constant temperature of 120 ℃ by using a constant-temperature heating table to enhance van der Waals force between the gallium oxide microwires and the graphene so that the contact of the gallium oxide microwires and the graphene is more compact.

Step 3, preparing a contact electrode: and respectively preparing electrodes at two ends of the gallium oxide and the graphene to obtain the n-type gallium oxide microwire/p-type graphene heterogeneous pn junction self-powered ultraviolet photoelectric detector.

FIG. 2 is an IV curve diagram of an n-type gallium oxide/p-type graphene pn junction under dark and 235nm illumination, and the characteristic of the pn junction of a device can be seen by an asymmetric IV curve of dark condition; under the condition of illumination, the photon-generated carriers are separated under an electric field to generate a large photocurrent, and the light-dark ratio of the device is more than 10⁵；

FIG. 3 is a graph of It cycle under 0V bias and 235nm illumination of the gallium oxide microwire/graphene heterogeneous pn junction solar blind ultraviolet detector of the present invention, due to the existence of the built-in electric field, the photo-generated electron-hole pairs can be effectively separated, so that the device can work under 0V, and when the light source is repeatedly turned on and off, the photocurrent is stable, which can indicate that the device is stable and reliable;

FIG. 4 is a graph showing the photoresponse and detectivity of the gallium oxide microwire/graphene heterogeneous pn junction solar-blind ultraviolet detector under 0V bias voltage, wherein the responsivity can reach 270mA/W, and the device has good solar-blind selectivity in the solar-blind band, and simultaneously has higher detectivity which can reach 10¹²；

FIG. 5 is a responsivity curve diagram of a gallium oxide microwire/graphene heterojunction solar-blind ultraviolet detector under different bias voltages. When an external bias is applied, the responsivity of the device can reach 10A/W, which shows that the device can work under different biases, and simultaneously can keep good solar blind selectivity, and further shows that the device has better stability.

Example 2:

this example is the same as example 1 except for the following features; in this embodiment, the n-type gallium oxide in step 1 may be replaced by other n-type oxides, such as n-type materials like zinc oxide and tin dioxide.

The invention is described above with reference to the accompanying drawings, it is obvious that the implementation of the invention is not limited in the above manner, and it is within the scope of the invention to adopt various modifications of the inventive method concept and solution, or to apply the inventive concept and solution directly to other applications without modification.