阅读说明：本技术 氧化镓基日盲探测器及其制备方法 (Gallium oxide based solar blind detector and preparation method thereof ) 是由 龙世兵 吴枫 于 2019-07-31 设计创作，主要内容包括：本发明提供一种日盲光电探测器及其制备方法,日盲光电探测器包括：含氧化镓外延层的氧化镓衬底；源极和漏极,分别与氧化镓衬底形成肖特基接触；氧化硅钝化层,形成于氧化镓衬底、源极和漏极之上；从氧化硅钝化层开设置氧化镓衬底内的沟槽；氧化铝层,形成于沟槽底部和沟槽侧壁；栅极,沟槽的氧化铝层之上及氧化硅钝化层之上。本发明采用特定的三端结构,通过栅极可以调节沟道的载流子浓度,从而可以很便利的调节器件的暗电流。(the invention provides a solar blind photoelectric detector and a preparation method thereof, wherein the solar blind photoelectric detector comprises: a gallium oxide substrate containing a gallium oxide epitaxial layer; the source electrode and the drain electrode are respectively in Schottky contact with the gallium oxide substrate; a silicon oxide passivation layer formed on the gallium oxide substrate, the source electrode and the drain electrode; opening a trench in the gallium oxide substrate from the silicon oxide passivation layer; the aluminum oxide layer is formed at the bottom of the groove and on the side wall of the groove; a gate, an aluminum oxide layer over the trench and a silicon oxide passivation layer. The invention adopts a specific three-terminal structure, and the carrier concentration of the channel can be adjusted through the grid, thereby conveniently adjusting the dark current of the device.)

1. a solar-blind photodetector, characterized by comprising:

A gallium oxide substrate containing a gallium oxide epitaxial layer;

The source electrode and the drain electrode are respectively in Schottky contact with the gallium oxide substrate;

A silicon oxide passivation layer formed on the gallium oxide substrate, the source electrode and the drain electrode;

A trench opened from the silicon oxide passivation layer into the gallium oxide substrate;

the aluminum oxide layer is formed at the bottom of the groove and on the side wall of the groove;

A gate, an aluminum oxide layer over the trench and a silicon oxide passivation layer.

2. the solar-blind photodetector of claim 1, wherein the gallium oxide substrate comprises, from bottom to top: an iron-doped beta gallium oxide semi-insulating substrate, an unintentionally doped gallium oxide buffer layer and a silicon-doped gallium oxide epitaxial layer.

3. The solar-blind photodetector according to claim 2, characterized in that the thickness of said buffer layer of unintentionally doped gallium oxide is 200-1000nm and the doping concentration of said epitaxial layer of silicon-doped gallium oxide is 10¹⁶～10¹⁸cm^-3。

4. The solar blind photodetector of claim 1, wherein the material of the source and drain electrodes is platinum.

5. The solar-blind photodetector of claim 2, wherein the bottom of the trench opens to the silicon-doped gallium oxide epitaxial layer of the gallium oxide substrate.

6. A method for manufacturing a solar blind photodetector is characterized by comprising the following steps:

preparing a gallium oxide substrate containing a gallium oxide epitaxial layer;

Photoetching and patterning, and performing device isolation on the gallium oxide substrate by adopting reactive ion beam etching;

Depositing a source electrode and a drain electrode, and forming Schottky contact with gallium oxide;

Growing a whole layer of silicon oxide passivation layer on the surface;

Etching the silicon oxide passivation layer and the gallium oxide with a set thickness by adopting reactive ion beam etching to form a groove structure, thereby realizing a normally-off gallium oxide MOSFET;

Depositing an aluminum oxide dielectric layer by adopting an atomic layer deposition method;

A gate is formed over the aluminum oxide layer of the trench and over the silicon oxide passivation layer.

7. The method according to claim 6, wherein the source electrode and the drain electrode are deposited by a platinum/titanium/gold three-layer structure, wherein the thickness of platinum is 10-60nm, the thickness of titanium is 5-20nm, and the thickness of gold is 10-100 nm.

8. The method of claim 6, further comprising:

And repairing damage caused by etching by annealing, and reducing the interface state density to prepare the gallium oxide substrate containing the gallium oxide epitaxial layer.

9. The method according to claim 6, wherein the gallium oxide substrate comprises, from bottom to top: an iron-doped beta gallium oxide semi-insulating substrate, an unintentionally doped gallium oxide buffer layer and a silicon-doped gallium oxide epitaxial layer.

10. the method according to claim 9, wherein the thickness of the unintentionally doped gallium oxide buffer layer is 200-1000nm, and the doping concentration of the silicon-doped gallium oxide epitaxial layer is 10¹⁶～10¹⁸cm^-3。

Technical Field

The invention relates to the technical field of semiconductors, and further relates to a gallium oxide-based solar blind detector and a preparation method of the gallium oxide-based solar blind detector.

Background

The solar blind refers to ultraviolet light with the wavelength range of 200-280nm, the solar blind photoelectric detector has the outstanding advantages of small background interference and the like, and has wide application prospects in the fields of warning, guidance and the like. The forbidden band width of gallium oxide directly corresponds to the solar blind wave band, and is a natural solar blind detection material. The performance of the optical detector is mainly characterized by the following parameters: light responsivity, dark current, specific detectivity, response speed, quantum efficiency, and the like. Due to the limitation of material quality and device structure, the performance of the existing gallium oxide based solar blind detector is poor and is not enough to meet the requirement of practical application. The existing gallium oxide-based solar blind detector usually adopts a two-end structure of a metal-semiconductor-metal (MSM) and a Schottky junction (Schottky diode), but the dark current of the detectors with the two structures is generally larger and cannot be adjusted after the device is prepared. In addition, the metal-semiconductor-metal structure detector cannot achieve high gain and large bandwidth at the same time, and the response speed of the device is slow. The detector with the Schottky structure is usually formed by combining metal with high work function and gallium oxide, the formed Schottky barrier can reduce dark current of the device to a certain extent, and meanwhile, a built-in electric field can accelerate the collection of carriers, so that the light response speed of the device is improved, but the light response of the solar blind detector with the structure is usually low.

therefore, the technical problems to be solved are as follows: the source and drain electrodes form good Schottky contact; implementation of normally-off metal-oxide-semiconductor field effect transistors (MOSFETs); reasonable etching depth of the gate groove and damage repair.

Disclosure of Invention

Technical problem to be solved

(II) technical scheme

According to an aspect of the present invention, there is provided a solar blind photodetector including:

A gallium oxide substrate containing a gallium oxide epitaxial layer;

the source electrode and the drain electrode are respectively in Schottky contact with the gallium oxide substrate;

a silicon oxide passivation layer formed on the gallium oxide substrate, the source electrode and the drain electrode;

A trench opened from the silicon oxide passivation layer into the gallium oxide substrate;

The aluminum oxide layer is formed at the bottom of the groove and on the side wall of the groove;

A gate, an aluminum oxide layer over the trench and a silicon oxide passivation layer.

In a further embodiment, the gallium oxide substrate comprises, from bottom to top: an iron-doped beta gallium oxide semi-insulating substrate, an unintentionally doped gallium oxide buffer layer and a silicon-doped gallium oxide epitaxial layer.

In a further embodiment, the thickness of the gallium oxide buffer layer is unintentionally doped200-1000nm, and the doping concentration of the silicon-doped gallium oxide epitaxial layer is 10¹⁶～10¹⁸cm^-3。

in a further embodiment, the material of the source and drain electrodes is platinum.

In a further embodiment, the trench bottom of the trench opens to a silicon-doped gallium oxide epitaxial layer of the gallium oxide substrate.

according to another aspect of the present invention, there is also provided a method for manufacturing a solar-blind photodetector, including:

preparing a gallium oxide substrate containing a gallium oxide epitaxial layer;

Photoetching and patterning, and performing device isolation on the gallium oxide substrate by adopting reactive ion beam etching;

depositing a source electrode and a drain electrode, and forming Schottky contact with gallium oxide;

growing a whole layer of silicon oxide passivation layer on the surface;

Etching the silicon oxide passivation layer and the gallium oxide with a set thickness by adopting reactive ion beam etching to form a groove structure, thereby realizing a normally-off gallium oxide MOSFET;

depositing an aluminum oxide dielectric layer by adopting an atomic layer deposition method;

a gate is formed over the aluminum oxide layer of the trench and over the silicon oxide passivation layer.

in a further embodiment, the metal used for depositing the source electrode and the drain electrode is a platinum/titanium/gold three-layer structure, wherein the thickness of platinum is 10-60nm, the thickness of titanium is 5-20nm, and the thickness of gold is 10-100 nm.

in a further embodiment, the method of making further comprises:

and repairing damage caused by etching by annealing, and reducing the interface state density to prepare the gallium oxide substrate containing the gallium oxide epitaxial layer.

in a further embodiment, the gallium oxide substrate comprises, from bottom to top: an iron-doped beta gallium oxide semi-insulating substrate, an unintentionally doped gallium oxide buffer layer and a silicon-doped gallium oxide epitaxial layer.

In a further embodiment, the thickness of the gallium oxide buffer layer is unintentionally doped200-1000nm, and the doping concentration of the silicon-doped gallium oxide epitaxial layer is 10¹⁶～10¹⁸cm^-3。

(III) advantageous effects

the gallium oxide epitaxial film grown by molecular beam epitaxy has high film quality, and the doping concentration of the epitaxial layer is 10¹w～10¹⁸cm^-3And the buffer layer is favorable for preventing iron in the substrate from diffusing into the epitaxial layer, so that the stability of the device is improved.

The invention adopts a three-terminal structure, and the carrier concentration of a channel can be adjusted through the grid, so that the dark current of a device can be conveniently adjusted;

According to the invention, platinum is adopted as a source electrode and a drain electrode of the device, and Schottky contact is formed between the platinum and gallium oxide, and the existence of a Schottky barrier is favorable for further reducing the dark current of the device;

According to the invention, platinum is used as a source electrode and a drain electrode of the device and forms Schottky contact with gallium oxide, so that a depletion region with a certain width exists at the contact position of metal and gallium oxide, and the existence of a built-in electric field in the depletion region is favorable for collecting carriers, thereby improving the response speed of the device; meanwhile, due to the adoption of rapid thermal annealing, interface damage caused by etching is repaired, and the mobility of carriers in a channel is improved, so that the response speed of the device is improved;

Because the MOSFET structure has high-gain amplification characteristic and high-quality epitaxial thin film, the device has ultrahigh light responsivity and specific detectivity;

and (4) a wide working interval. According to the invention, the reactive ion beam etching is adopted to etch the gallium oxide to a certain depth to form a groove structure, so that a normally-off gallium oxide Metal Oxide Semiconductor Field Effect Transistor (MOSFET) can be formed, and the effective working interval of the device can be increased.

drawings

Fig. 1-7 are flow charts of methods for fabricating gallium oxide-based solar blind detectors according to embodiments of the present invention.

Detailed Description

In order that the objects, technical solutions and advantages of the present invention will become more apparent, the present invention will be further described in detail with reference to the accompanying drawings in conjunction with the following specific embodiments.

it should be noted that in the drawings or description, the same drawing reference numerals are used for similar or identical parts. Implementations not depicted or described in the drawings are of a form known to those of ordinary skill in the art. Additionally, while exemplifications of parameters including particular values may be provided herein, it is to be understood that the parameters need not be exactly equal to the respective values, but may be approximated to the respective values within acceptable error margins or design constraints. Directional phrases used in the embodiments, such as "upper," "lower," "front," "rear," "left," "right," and the like, refer only to the orientation of the figure. Accordingly, the directional terminology used is intended to be in the nature of words of description rather than of limitation.

The existing gallium oxide-based solar blind detector is mainly based on two-end structures of a metal-semiconductor-metal (MSM) and a Schottky junction (Schottky diode), but the dark current of the detectors with the two structures is generally larger and cannot be adjusted after the device is prepared. In addition, the metal-semiconductor-metal structure detector cannot achieve high gain and large bandwidth at the same time, and the response speed of the device is slow. Whereas the optical responsivity of a detector of schottky structure is generally low. Therefore, the embodiment of the invention provides a novel gallium oxide-based solar blind detector with a three-terminal structure, which can realize extremely low dark current and controllable dark current, and meanwhile, the device has extremely high light responsivity and response speed. The basic scheme of the invention is to prepare a metal-oxide-semiconductor field effect transistor (MOSFET) with a source electrode and a drain electrode having Schottky junction characteristics.

In this application, a solar blind detector refers to a device capable of receiving and detecting ultraviolet radiation, and the wavelength of the detected ultraviolet light is less than 280 nm.

The following process steps are described for gallium oxide (Ga) as shown in FIG. 1₂O₃) On the sample. Here, the gallium oxide sample may include multiple epitaxial layers, for example from bottom to top: an iron-doped beta gallium oxide semi-insulating substrate 101, an unintentionally doped gallium oxide buffer layer 102 and a silicon-doped gallium oxide epitaxial layer 103. Wherein the iron is doped with a gallium oxide moietyThe preparation process of the insulating substrate 101 is to adopt a beta gallium oxide single crystal grown by pulling and growing, the unintended doped gallium oxide buffer layer 102 is grown by adopting an HVPE (hydride vapor phase epitaxy) method, the growth thickness can be 1 μm, the buffer layer is grown on a (010) surface of an iron-doped beta gallium oxide semi-insulating substrate, the silicon-doped gallium oxide epitaxial layer 103 is deposited by adopting an MBE (molecular beam epitaxy) method, and the deposition thickness can be 200 nm.

The layer may be prepared by various other deposition or growth methods, including but not limited to methods such as MOCVD or PLD, to produce epitaxial films of gallium oxide.

Referring to fig. 2, the sample is patterned by photolithography, and the sample is isolated by reactive ion beam etching; the parameters of the etching can be: by Cl₂Etching with Ar gas, wherein Cl₂The flow rate was 15sccm, the flow rate of Ar was 5sccm, the ICP (inductively coupled plasma) power was 400W, and the RF power was 200W.

referring to FIG. 3, the source and drain electrodes were electron beam evaporation deposited using standard photolithographic lift-off processes using platinum/titanium/gold, and gallium oxide (Ga)₂O₃) Forming Schottky contact, wherein the thickness of the electrode is 40nm/10nm/50nm respectively; platinum thickness range: 10-60nm, titanium thickness range: 5-20nm, gold thickness range: 10-100 nm. The platinum is used as an electrode, so that the dark current of the device is reduced, and the response speed of the device is improved. It should be noted that the metal here can also be other metals used for schottky contact, including but not limited to nickel and gold.

referring to FIG. 4, a whole layer of silicon dioxide (SiO) with a thickness of 100nm is grown on the surface of the device by PECVD₂) A passivation layer 120;

referring to FIG. 5, reactive ion beam etching was used to etch Si0₂Etching the layer 120 and gallium oxide with a certain thickness (120nm) to form a trench structure, thereby realizing a normally-off gallium oxide MOSFET;

Referring to fig. 6, an alumina dielectric layer 130 having a thickness of 30nm is deposited by atomic layer deposition. Then adopting rapid thermal annealing to repair the damage caused by etching and reducing the density of interface state, wherein the annealing condition is 450-500℃，N₂the treatment was carried out for 1 minute under a (nitrogen) atmosphere.

referring to FIG. 7, the gate metal titanium/gold was deposited by electron beam evaporation to a thickness of 20nm/80nm, respectively. Therefore, the special three-terminal device structure can adjust the carrier concentration of a channel through the grid electrode, so that the dark current of the device can be conveniently adjusted.

it is to be noted that, in the attached drawings or in the description, the implementation modes not shown or described are all the modes known by the ordinary skilled person in the field of technology, and are not described in detail. Furthermore, the definitions of the various elements are not limited to the specific structures, shapes or modes mentioned in the embodiments, and those skilled in the art can easily modify or replace them:

Similarly, it should be appreciated that in the foregoing description of exemplary embodiments of the disclosure, various features of the disclosure are sometimes grouped together in a single embodiment, figure, or description thereof for the purpose of streamlining the disclosure and aiding in the understanding of one or more of the various disclosed aspects. However, the disclosed method should not be interpreted as reflecting an intention that: that is, the claimed disclosure requires more features than are expressly recited in each claim. Rather, as the following claims reflect, disclosed aspects lie in less than all features of a single foregoing disclosed embodiment. Thus, the claims following the detailed description are hereby expressly incorporated into this detailed description, with each claim standing on its own as a separate embodiment of this disclosure.

Unless otherwise indicated, the numerical parameters set forth in the specification and attached claims are approximations that can vary depending upon the desired properties sought to be obtained by the present invention. In particular, all numbers expressing quantities of ingredients, reaction conditions, and so forth used in the specification and claims are to be understood as being modified in all instances by the term "about". Generally, the expression is meant to encompass variations of ± 10% in some embodiments, 5% in some embodiments, 1% in some embodiments, 0.5% in some embodiments by the specified amount.

the above-mentioned embodiments are intended to illustrate the objects, technical solutions and advantages of the present invention in further detail, and it should be understood that the above-mentioned embodiments are only exemplary embodiments of the present invention and are not intended to limit the present invention, and any modifications, equivalents, improvements and the like made within the spirit and principle of the present invention should be included in the protection scope of the present invention.