Photoelectric detector

Abstract

The utility model relates to the field of semiconductor optoelectronic devices, and provides a photoelectric detector which comprises a substrate, a buffer layer, a nanorod layer, an upper electrode layer and a lower electrode layer. The buffer layer is arranged between the substrate and the nanorod layer; the nano-column layer comprises a nano-column and a semiconductor, one end of the nano-column is connected with the semiconductor, and the other end of the nano-column is connected with the upper electrode layer; the lower electrode layer is laid on the semiconductor, and the nanorods penetrate through the lower electrode layer; schottky contact is formed between the upper electrode layer and the nanorods. Schottky contact is formed between the lower electrode layer and the nanorods, and Schottky contact is formed between the lower electrode layer and the semiconductor. The utility model discloses a nano-column detector, which is used for overcoming the defects that the structure of the existing nano-column detector restricts the absorption of photon-generated carriers on a nano-column, the transmission distance of the photon-generated carriers is increased, and the transmission distance of the photon-generated carriers affects the efficiency and response speed of a device, electrodes are formed at the two ends of the nano-column, the carrier path of the device is effectively shortened, and the performance of the device is improved. And the efficiency and response speed of the device are improved.

Description

Technical Field

[0001] The utility model relates to the technical field of semiconductor optoelectronic devices, in particular to a photoelectric detector. Background Art

[0002] Ultraviolet detection technology has now been widely used in aerospace, medical, fire warning and other fields, and semiconductor ultraviolet photodetectors are gradually developing in the direction of miniaturization, integration and diversification, which inevitably requires its materials to change to gallium nitride or silicon carbide. At the same time, it also puts forward higher requirements on the quality of ultraviolet detection materials, device structure and performance indicators.

[0003] In recent years, due to the improvement of nano-scale methods, nano-structures have been widely used in semiconductor materials, such as nano-pillars and nano-holes. However, the common structure of nano-pillar detectors is still the MSM structure, which restricts the absorption of photogenerated carriers on the nano-pillars to a certain extent, and increases the transmission distance of photogenerated carriers. The transmission distance of photogenerated carriers will affect the efficiency and response speed of the device to a certain extent. The performance of the device is not enough to meet the needs of the application, and it needs to be further improved. Utility Model Content

[0004] The utility model provides a photoelectric detector to solve the problem that the structure of the existing nanocolumn detector restricts the absorption of photogenerated carriers on the nanocolumn, while increasing the transmission distance of the photogenerated carriers. The transmission distance of the photogenerated carriers will affect the efficiency and response speed of the device to a certain extent. By forming electrodes at both ends of the nanocolumn, the carrier path of the device is effectively shortened, thereby improving the efficiency and response speed of the device.

[0005] The utility model provides a photoelectric detector, comprising a substrate, a buffer layer, a nanocolumn layer, an upper electrode layer and a lower electrode layer;

[0006] The buffer layer is disposed between the substrate and the nanocolumn layer;

[0007] The nanocolumn layer includes nanocolumns and semiconductors, one end of the nanocolumn is connected to the semiconductor, and the other end is connected to the upper electrode layer;

[0008] The lower electrode layer is laid on the semiconductor, and the nanorods penetrate the lower electrode layer;

[0009] A Schottky contact is formed between the upper electrode layer and the nanopillars;

[0010] A Schottky contact is formed between the lower electrode layer and the nano-pillars, and a Schottky contact is formed between the lower electrode layer and the semiconductor.

[0011] According to the photoelectric detector provided by the utility model, a graphene layer is arranged at one end of the upper electrode layer that is not connected to the nanocolumn.

[0012] According to the photoelectric detector provided by the utility model, the graphene layer is a single-layer graphene.

[0013] According to the photoelectric detector provided by the utility model, the height of the nanocolumn is 400-800 nanometers (nm) and the diameter is 300-800 nanometers.

[0014] According to the photoelectric detector provided by the utility model, the distance between the nano-pillars is 200-500 nanometers.

[0015] According to the photoelectric detector provided by the utility model, the thickness of the upper electrode layer is 100-200 nanometers, and the thickness of the lower electrode layer is 100-200 nanometers.

[0016] According to the photoelectric detector provided by the utility model, the thickness of the semiconductor is 1-2 micrometers (μm).

[0017] The photoelectric detector provided in this application has the following beneficial effects:

[0018] By depositing metal electrodes at both ends of the nanopillars and limiting the active area on the nanopillars, the size of the active area and the transmission path of the photogenerated carriers can be effectively controlled, the transmission path of the photogenerated carriers can be effectively shortened, and the comprehensive performance of the ultraviolet photodetector can be improved. It also greatly simplifies the preparation process and is easy to mass produce. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the technical solutions in the present invention or the prior art, a brief introduction will be given below to the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0020] Figure 1 This is one of the structural schematic diagrams of the photoelectric detector provided by the embodiment of the utility model;

[0021] Figure 2 This is the second structural schematic diagram of the photoelectric detector provided in the embodiment of the utility model.

[0022] in:

[0023] 1-substrate; 2-buffer layer; 3-lower electrode layer; 4-nanopillars; 5-upper electrode layer;

[0024] 6-graphene layer; 7-semiconductor. DETAILED DESCRIPTION

[0025] In order to make the purpose, technical solution and advantages of the utility model clearer, the technical solution of the utility model will be described clearly and completely in conjunction with the drawings in the utility model. Obviously, the described embodiments are part of the embodiments of the utility model, not all of the embodiments. Based on the embodiments in the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

[0026] Figure 1 This is one of the structural schematic diagrams of the photoelectric detector provided by the embodiment of the utility model;

[0027] Figure 2 This is the second structural schematic diagram of the photoelectric detector provided in the embodiment of the utility model.

[0028] like Figure 1 and Figure 2 As shown, this embodiment provides a photodetector, including a substrate 1, a buffer layer 2, a nanocolumn layer, an upper electrode layer 5 and a lower electrode layer 3;

[0029] The buffer layer 2 is arranged between the substrate 1 and the nanocolumn layer;

[0030] The nanocolumn layer includes a nanocolumn 4 and a semiconductor 7, one end of the nanocolumn 4 is connected to the semiconductor 7, and the other end is connected to the upper electrode layer 5;

[0031] The lower electrode layer 3 is laid on the semiconductor 7, and the nanorods 4 penetrate the lower electrode layer 3;

[0032] A Schottky contact is formed between the upper electrode layer 5 and the nano-pillars;

[0033] A Schottky contact is formed between the lower electrode layer 3 and the nano-pillars 4 , and a Schottky contact is formed between the lower electrode layer 3 and the semiconductor 7 .

[0034] Among them, Schottky contact refers to the bending of the semiconductor energy band at the interface when metal and semiconductor materials are in contact, forming a Schottky barrier. The existence of the barrier leads to a large interface resistance. The corresponding is the ohmic contact, where the barrier at the interface is very small or there is no contact barrier. Schottky barrier refers to a metal-semiconductor contact with rectification characteristics, just like a diode has rectification characteristics. It is a region with rectification effect formed on the metal-semiconductor boundary. The junction capacitance of Schottky is very small, to a few tenths of a picofarad.

[0035] In the exemplary embodiment, a graphene layer 6 is disposed at one end of the upper electrode layer 5 that is not connected to the nanorod 4 .

[0036] In practice, the graphene layer 6 is formed in one piece, that is, all the graphene layers on the nano-pillars are connected to each other, and the graphene layer is a complete plane.

[0037] In an exemplary embodiment, the graphene layer 6 is a single layer of graphene.

[0038] In an exemplary embodiment, the nanorod 4 has a height of 400-800 nanometers and a diameter of 300-800 nanometers.

[0039] In practical applications, the diameter difference between the upper and lower diameters of the nanocolumns is 50-80 nanometers. In practice, it is difficult to achieve uniform vertical nanocolumns during the actual etching process of the nanocolumns, so the uniformity of the nanocolumns can be ensured as much as possible by controlling the diameter difference between the upper and lower diameters.

[0040] In practical applications, the distance between nanopillars is 200-500 nanometers.

[0041] In an exemplary embodiment, the thickness of the upper electrode layer 5 is 100-200 nanometers, and the thickness of the lower electrode layer 3 is 100-200 nanometers.

[0042] In an exemplary embodiment, the semiconductor 7 has a thickness of 1-2 micrometers.

[0043] The solution of the utility model also provides a method for preparing a photoelectric detector, which can be applied to prepare any of the above-mentioned photoelectric detectors, comprising the following steps:

[0044] 1. Pre-treat the substrate;

[0045] 2. Growing a buffer layer on the substrate;

[0046] 3. Growing AlGaN semiconductor on the buffer layer;

[0047] 4. Epitaxially arrange a layer of SiO2 on the surface of the AlGaN semiconductor;

[0048] 5. Use nanoimprint technology to form nanodisc shapes on SiO2;

[0049] 6. Use ICP to etch SiO2, leaving a SiO2 nanodisk pattern;

[0050] 7. Etch the AlGaN semiconductor below to form nanopillars;

[0051] 8. Using ALD technology, deposit 50-100 nanometers thick SiO2 on the nano-sample;

[0052] 9. Use ICP etching technology to remove the SiO2 deposited on the plane, leaving only the SiO2 on the sidewalls of the nanocolumns;

[0053] 10. Use magnetron sputtering technology to deposit metal electrodes on the sample surface, use BOE solution to remove the metal on the side wall of the nanocolumn, and perform rapid thermal annealing in a nitrogen atmosphere to form Schottky contact between the metal electrode and the ultra-short period superlattice;

[0054] 11. By transferring a single layer of graphene to the upper surface of the nanocolumn, it forms the upper electrode of the nanocolumn together with the metal electrode.

[0055] In the above steps,

[0056] The following is a detailed description of the method for preparing the photoelectric detector provided by the solution of the present application with a specific embodiment, including:

[0057] 1) Epitaxy is performed on a sapphire substrate using a metal organic vapor phase epitaxy (MOVPE) technique: At a high temperature of 1100 degrees Celsius (°C) and a reaction chamber pressure of 100 Torr, the sapphire substrate 1 is purged with hydrogen (H2) to remove surface contamination.

[0058] 2) Nitridation of sapphire substrate: pre-introduce trimethylaluminum (TMA) to make the surface of the sapphire substrate rich in aluminum (Al), then cool to 570°C, use high-purity H2 as carrier gas, and pass ammonia (NH3) into the reaction chamber to achieve the purpose of nitridation.

[0059] 3) Raise the temperature to 800°C, use H2 as carrier gas, introduce TMA and NH3 to epitaxially grow a 20nm thick AlN low-temperature buffer layer, then raise the temperature to 1090°C, and continue to epitaxially grow a 1μm AlN buffer layer on the low-temperature buffer layer.

[0060] 4) Based on step 3), TMA and trimethylgallium (TMG) are introduced as group III sources and NH3 as group V source to epitaxially grow Al x GaN (1-x) Mixed crystal semiconductors are formed by controlling the flow rate and growth time of the two gases to form their specified Al x GaN (1-x) Mixed crystal semiconductor.

[0061] 5) Use PECVD to epitaxially grow a 200nm layer of silicon dioxide (SiO2) on the surface of the ultra-short period superlattice, then spin-coat photoresist and perform nanoimprinting to transfer the nanopattern to the sample surface to form disks.

[0062] 6) The ICP (Inductively Coupled Plasma) technology is used to etch the lower SiO2 layer to form nanodisks; then the SiO2 pattern is used as a mask and the ICP switching gas is used to etch the AlGaN mixed crystal semiconductor to form a nanocolumn array structure with an upper diameter of 400nm, a lower diameter of 430nm, and a height of 600nm.

[0063] 7) The sample was placed in a BOE (Buffered Oxide Etch) solution to remove the SiO2 nanodisk structure on the upper surface; the sample was then placed in a 10% potassium hydroxide (KOH) solution for 10 minutes (min) to fully remove the etching damage on the surface and release the stress.

[0064] 8) Using ALD technology, 50nm thick SiO2 is deposited on the nano-sized sample; then using the anisotropy of ICP, the SiO2 in the vertical direction is etched downward, leaving only the SiO2 on the sidewalls of the nano-columns.

[0065] 9) When the vacuum degree is 10 -5 In Torr's electron beam evaporation system, titanium / gold composite metal layers with thicknesses of 10nm and 200nm are deposited in sequence to serve as the upper and lower metal electrodes of the nanocolumns.

[0066] 10) The sample is placed in a BOE solution and placed in an ultrasonic environment to fully remove SiO2 and metal from the side walls of the nanorods.

[0067] 11) Thermal annealing was performed at 400° C. for 300 s in a nitrogen atmosphere to obtain a metal electrode that formed a Schottky contact with the substrate.

[0068] 12) Transferring a single layer of graphene to the surface of the nanorod to form an upper electrode with the metal on the end face of the nanorod.

[0069] The preparation of an upper and lower electrode nanocolumn ultraviolet photodetector was completed by the above method.

[0070] The device embodiments described above are merely illustrative, wherein the units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, i.e., they may be located in one place, or they may be distributed on multiple network units. Some or all of the modules may be selected according to actual needs to achieve the purpose of the scheme of this embodiment. Those of ordinary skill in the art may understand and implement it without creative effort.

[0071] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the utility model, rather than to limit it. Although the utility model has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments of the utility model.

Claims

1. A photodetector, characterized in that It includes a substrate, a buffer layer, a nanocolumn layer, an upper electrode layer and a lower electrode layer; The buffer layer is disposed between the substrate and the nanocolumn layer; The nanocolumn layer comprises nanocolumns and semiconductors, one end of the nanocolumn is connected to the semiconductor, and the other end is connected to the upper electrode layer; The lower electrode layer is laid on the semiconductor, and the nanocolumns penetrate the lower electrode layer; A Schottky contact is formed between the upper electrode layer and the nano-pillars; A Schottky contact is formed between the lower electrode layer and the nano-pillars, and a Schottky contact is formed between the lower electrode layer and the semiconductor.

2. The photodetector according to claim 1, characterized in that: A graphene layer is disposed at one end of the upper electrode layer that is not connected to the nanocolumn.

3. The photodetector according to claim 2, characterized in that: The graphene layer is a single-layer graphene.

4. The photodetector according to claim 1, characterized in that: The nanocolumn has a height of 400-800 nanometers and a diameter of 300-800 nanometers.

5. The photodetector according to claim 1 or 4, characterized in that: The distance between the nano columns is 200-500 nanometers.

6. The photodetector according to claim 1, characterized in that: The thickness of the upper electrode layer is 100-200 nanometers, and the thickness of the lower electrode layer is 100-200 nanometers.

7. The photodetector according to claim 1, characterized in that: The semiconductor has a thickness of 1-2 microns.

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