Gallium nitride-based recessed gate MOS structure ultraviolet photodetector and manufacturing method thereof

Abstract

The present application discloses a gallium nitride-based recessed gate MOS structure ultraviolet photodetector, comprising: a substrate; a buffer layer located on the upper surface of the substrate; a first n + ‑GaN layer, located on the upper surface of the buffer layer; n ‑ ‑GaN layer, located in the first n + The upper surface of the ‑GaN layer; the p‑GaN layer, located on the n ‑ The upper surface of the ‑GaN layer; the second n + ‑GaN layer, located on the upper surface of the p‑GaN layer, the p‑GaN layer and the second n + The GaN layer is formed with a ‑ The first notch on the surface of the ‑GaN layer; the gate dielectric layer, located on the first n + The upper surface of the GaN layer, the second n + The upper surface of the GaN layer and the surface of the first recess, the gate dielectric layer, the second n + The p-GaN layer and the p-GaN layer are formed with a second recess; the drain electrode is located at the first n + The PN junction of the present invention enables the gate voltage to regulate its photoelectric characteristics. By applying a positive gate voltage to the device, the light-to-dark current ratio of the UV detection can exceed 10. 6 , while the device has an extremely fast rise time τ rise and decay time τ decay .

Description

Technical Field

[0001] The present invention relates to the field of semiconductors, and in particular to a gallium nitride-based recessed gate MOS (metal oxide semiconductor) structure ultraviolet photodetector and a manufacturing method thereof. Background Art

[0002] Gallium nitride (GaN), a current hotspot and frontier in global semiconductor research, holds broad promise in optoelectronics, high-temperature, high-power, and high-frequency microwave devices due to its wide direct band gap, strong atomic bonds, high thermal conductivity, excellent chemical stability (virtually impervious to acid corrosion), and strong radiation resistance. This makes it an ideal material for ultraviolet photodetectors. Ultraviolet photodetectors (UVPDs), due to their ability to capture, identify, and visualize short-wavelength optical information, have been widely used in military and civilian applications such as secure communications, imaging, biological detection, chemical analysis, and daily life monitoring.

[0003] Currently, the light-to-dark current ratio of most ultraviolet photodetectors cannot reach a very high value. In addition, most detectors do not have the ability to regulate their photoelectric characteristics by gate voltage. Summary of the Invention

[0004] The present invention addresses the above-mentioned problems, overcomes at least one of the drawbacks, and proposes a gallium nitride-based recessed gate MOS structure ultraviolet photodetector and a manufacturing method thereof.

[0005] The technical solution adopted by the present invention is as follows:

[0006] A gallium nitride-based recessed gate MOS structure ultraviolet photodetector, comprising:

[0007] substrate;

[0008] a buffer layer, located on the upper surface of the substrate;

[0009] First n + - a GaN layer located on the upper surface of the buffer layer;

[0010] n - -GaN layer, located on the first n + - the upper surface of the GaN layer;

[0011] The p-GaN layer is located on the n - - the upper surface of the GaN layer;

[0012] Second n + -GaN layer, located on the upper surface of the p-GaN layer, the p-GaN layer and the second n + -GaN layer is formed on the - - a first notch on the surface of the GaN layer;

[0013] The gate dielectric layer is located at the first n + -The upper surface of the GaN layer, the second n + -The upper surface of the GaN layer and the surface of the first recess, the gate dielectric layer, the second n + The -GaN layer and the p-GaN layer are formed with a second notch, and there are two second notches, one located on either side of the first notch;

[0014] Two drain electrodes, located on the first n + -GaN layer, and respectively located on both sides of the gate dielectric layer;

[0015] a gate electrode, located on an upper surface of the gate dielectric layer and corresponding to the first recess; and

[0016] The two source electrodes are respectively located at the corresponding second notches.

[0017] The present invention can be mass-produced. The presence of the PN junction in the present invention enables the gate voltage to regulate its photoelectric characteristics. By applying a positive gate voltage to the device, the light-to-dark current ratio of the UV detection can exceed 10 6 , while the device has an extremely fast rise time τ rise and decay time τ decay .

[0018] In actual application, the rise time τ rise Can be 1.34ms, decay time τ decay In addition, the photodetector’s responsivity can reach 37.99A / W, the external quantum efficiency can reach 12900%, and the specific detection rate D* can reach 7.28×10 12 Jones.

[0019] In one embodiment of the present invention, the first n + The thickness of the GaN layer is 0.5 μm-3 μm, and the carrier concentration is 1×10 19 cm -3 -5×10 19 cm -3 .

[0020] In one embodiment of the present invention, the n - -GaN layer thickness ranges from 2μm to 8μm, and the carrier concentration is 1×10 16 cm -3 -5×10 16 cm -3 .

[0021] In one embodiment of the present invention, the thickness of the p-GaN layer is 1 μm-2 μm, and the carrier concentration is 5×10 17 cm -3 -1×10 18 cm -3

[0022] In one embodiment of the present invention, the second n + The thickness of the GaN layer is 0.1 μm-1 μm, and the carrier concentration is 1×10 19 cm -3 -5×10 19 cm -3 .

[0023] In one embodiment of the present invention, the substrate is a sapphire substrate; and the gate dielectric layer is Al2O3.

[0024] The present application also discloses a method for preparing a gallium nitride-based recessed gate MOS structure ultraviolet photodetector, comprising the following steps:

[0025] S1, prepare the substrate, and deposit the buffer layer, the first n + -GaN layer, n - -GaN layer, p-GaN layer and the second n + -GaN layer to obtain an epitaxial wafer; in actual application, it can be deposited through the metal oxide chemical vapor deposition (MOCVD) process.

[0026] S2, etch the mesa of the epitaxial wafer so that the first n + - The GaN layer is partially exposed; in actual use, it can be etched using an inductively coupled plasma (ICP) process;

[0027] S3, for the second n + -GaN layer and p-GaN layer are etched to obtain an extension to n - - a first recess in the GaN layer;

[0028] S4. Depositing a gate dielectric layer on the outer surface of the epitaxial wafer; in actual use, an atomic layer deposition system (ALD) can be used for deposition.

[0029] S5, etching the gate dielectric layer located at the second n + -GaN layer, get the first groove, etch the first n + -The gate dielectric layer above the GaN layer is formed to obtain two second grooves, which are located on both sides of the gate dielectric layer; in actual use, the gate dielectric layer is corroded by BOE solution to expose the first groove (corresponding to the source electrode) and the second groove (corresponding to the drain electrode).

[0030] S6, etching the second n below the first groove + -GaN layer and p-GaN layer, the first groove and the space formed by etching together form a second notch, and there are two second notches, respectively located on both sides of the first notch;

[0031] S7, evaporating to obtain a drain electrode at the second groove, evaporating to obtain a source electrode at the second notch, and evaporating to obtain a gate electrode at a position of the gate dielectric layer corresponding to the first notch;

[0032] S8. Annealing the epitaxial wafer in an inert atmosphere.

[0033] Photodetectors made of transition metal sulfides are difficult to produce on a large scale. The present application has a complete and mature preparation process that can be mass-produced.

[0034] In one embodiment of the present invention, the first n + The thickness of the GaN layer is 0.5 μm-3 μm, and the carrier concentration is 1×10 19 cm -3 -5×10 19 cm -3 ; said n - -GaN layer thickness ranges from 2μm to 8μm, and the carrier concentration is 1×10 16 cm -3 -5×10 16 cm -3 The thickness of the p-GaN layer is 1 μm-2 μm, and the carrier concentration is 5×10 17 cm -3 -1×10 18 cm -3 ; The second n + The thickness of the GaN layer is 0.1 μm-1 μm, and the carrier concentration is 1×10 19 cm -3 -5×10 19 cm -3 .

[0035] In one embodiment of the present invention, the substrate is a sapphire substrate; and the gate dielectric layer is Al2O3.

[0036] In one embodiment of the present invention, in step S8 , the specific operation of annealing is: annealing at 750° C. in a N 2 atmosphere for 30 minutes.

[0037] The beneficial effects of the present invention are: the present invention can be mass-produced, and the presence of the PN junction of the present invention enables the gate voltage to regulate its photoelectric characteristics. By applying a positive gate voltage to the device, the light-to-dark current ratio of the ultraviolet detection can exceed 10 6, and the device has an extremely fast rise time τ rise and decay time τ decay . BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 is a schematic diagram of the substrate;

[0039] Figure 2 is a schematic diagram of an epitaxial wafer;

[0040] Figure 3 This is a schematic diagram of the epitaxial wafer after the mesa is etched;

[0041] Figure 4 is a schematic diagram of the epitaxial wafer after the first notch is etched;

[0042] Figure 5 This is a schematic diagram of the epitaxial wafer after the gate dielectric layer is deposited;

[0043] Figure 6 is a schematic diagram after etching the gate dielectric layer;

[0044] Figure 7 is a schematic diagram of etching to form a second recess;

[0045] Figure 8 This is a schematic diagram of a GaN-based recessed gate MOS structure ultraviolet photodetector;

[0046] Figure 9 This is a photo of a GaN-based recessed-gate MOS structure UV photodetector.

[0047] Figure 10 This is the IV characteristic curve of the GaN-based recessed gate MOS structure ultraviolet photodetector;

[0048] Figure 11 This is the transfer curve of the GaN-based recessed gate MOS structure UV photodetector;

[0049] Figure 12 This is the responsivity diagram of the GaN-based recessed gate MOS structure UV photodetector;

[0050] Figure 13 This is the external quantum efficiency diagram of the GaN-based recessed gate MOS structure ultraviolet photodetector;

[0051] Figure 14 This is the detection diagram of the GaN-based recessed gate MOS structure ultraviolet photodetector;

[0052] Figure 15 This is a light-to-dark current ratio diagram of a gallium nitride-based recessed gate MOS structure ultraviolet photodetector.

[0053] The reference numerals in the figures are:

[0054] 1. Substrate; 2. Buffer layer; 3. First n + -GaN layer; 4, n - -GaN layer; 5, p-GaN layer; 6, second n + -GaN layer; 7, gate dielectric layer; 71, first groove; 72, second groove; 8, drain electrode; 9, gate electrode; 10, source electrode; 11, first notch; 12, second notch. DETAILED DESCRIPTION

[0055] To make the objectives, technical solutions, and advantages of the embodiments of the present application more clear, the technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the accompanying drawings of the embodiments of the present application. Obviously, the described embodiments are only some of the embodiments of the present application, not all of the embodiments. Generally, the components of the embodiments of the present application described and shown in the drawings herein can be arranged and designed in various different configurations.

[0056] In the description of this application, it should be noted that the terms "inner" and "outer" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, or the orientations or positional relationships in which the product of this application is typically placed when in use. These terms are intended solely to facilitate the description of this application and simplify the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, be constructed, or operate in a specific orientation. Therefore, they should not be construed as limitations on this application. Furthermore, the terms "first" and "second" and the like are used solely for distinction and should not be construed as indicating or implying relative importance.

[0057] It should also be noted that, in the description of this application, unless otherwise expressly specified or limited, the terms "disposed" and "connected" should be understood in a broad sense. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to direct connections, indirect connections through an intermediate medium, or internal connections between two components. Those skilled in the art will understand the specific meanings of the above terms in this application based on the specific circumstances.

[0058] The present invention will be described in detail below with reference to the accompanying drawings.

[0059] like Figure 8 As shown, a gallium nitride-based recessed gate MOS structure ultraviolet photodetector includes:

[0060] Substrate 1;

[0061] a buffer layer 2, located on the upper surface of the substrate 1;

[0062] First n + -GaN layer 3, located on the upper surface of the buffer layer 2;

[0063] n - -GaN layer 4, located on the first n + - the upper surface of the GaN layer 3;

[0064] The p-GaN layer 5 is located on the n - - the upper surface of the GaN layer 4;

[0065] Second n + -GaN layer 6, located on the upper surface of p-GaN layer 5, p-GaN layer 5 and the second n + -GaN layer 6 is formed with a - - a first notch 11 on the surface of the GaN layer 4;

[0066] The gate dielectric layer 7 is located at the first n + -The upper surface of the GaN layer 3, the second n + -The upper surface of the GaN layer 6 and the surface of the first recess 11, the gate dielectric layer 7, the second n + The p-GaN layer 6 and the p-GaN layer 5 form a second notch 12 , and there are two second notches 12 , one located on either side of the first notch 11 ;

[0067] Two drain electrodes 8, located on the first n + - on the GaN layer 3 and respectively located on both sides of the gate dielectric layer 7;

[0068] a gate electrode 9 located on the upper surface of the gate dielectric layer 7 and corresponding to the first recess 11; and

[0069] The two source electrodes 10 are respectively located at the corresponding second notches 12 .

[0070] In this embodiment, the first n + The thickness of the GaN layer is 0.5 μm-3 μm, and the carrier concentration is 1×10 19 cm -3 -5×10 19 cm -3 .

[0071] In this embodiment, n - -GaN layer thickness ranges from 2μm to 8μm, and the carrier concentration is 1×10 16 cm -3 -5×10 16 cm -3 .

[0072] In this embodiment, the thickness of the p-GaN layer is 1 μm-2 μm, and the carrier concentration is 5×10 17 cm -3 -1×10 18 cm -3 .

[0073] In this embodiment, the second n + The thickness of the GaN layer is 0.1 μm-1 μm, and the carrier concentration is 1×10 19 cm -3 -5×10 19 cm -3 .

[0074] In this embodiment, the substrate 1 is a sapphire substrate; and the gate dielectric layer 7 is Al 2 O 3 .

[0075] This embodiment also discloses a method for preparing the gallium nitride-based recessed gate MOS structure ultraviolet photodetector of this embodiment, comprising the following steps:

[0076] S1, such as Figure 1 and 2 As shown, a substrate 1 is prepared, and a buffer layer 2, a first n + -GaN layer 3, n - -GaN layer 4, p-GaN layer 5 and the second n + -GaN layer 6, to obtain an epitaxial wafer; in actual use, it can be deposited by a metal oxide chemical vapor deposition (MOCVD) process.

[0077] S2, such as Figure 3 As shown, the mesa is etched on the epitaxial wafer to make the first n + -GaN layer 3 is partially exposed; in actual use, it can be etched using an inductively coupled plasma (ICP) process;

[0078] S3, such as Figure 4 As shown, for the second n + -GaN layer 6 and p-GaN layer 5 are etched to obtain a structure extending to n - - a first recess 11 in the GaN layer;

[0079] S4, such as Figure 5 As shown, a gate dielectric layer 7 is deposited on the outer surface of the epitaxial wafer; in actual use, an atomic layer deposition system (ALD) can be used for deposition.

[0080] S5, such as Figure 6 As shown, the gate dielectric layer 7 is etched at the second n + -GaN layer, two first grooves 71 are obtained, and two second grooves 71 are located on both sides of the first notch 11, respectively. +-The gate dielectric layer 7 above the GaN layer is provided with two second grooves 72, which are located on both sides of the gate dielectric layer 7; in actual use, the gate dielectric layer is corroded by BOE solution to expose the first groove 71 (corresponding to the source electrode) and the second groove 72 (corresponding to the drain electrode).

[0081] S6, such as Figure 7 As shown, the second n below the first groove is etched + -GaN layer 6 and p-GaN layer 5, the first groove and the space formed by etching together form a second notch 12, and there are two second notches 12, one located on both sides of the first notch 11;

[0082] S7, such as Figure 8 As shown, the drain electrode 8 is formed by evaporation at the second groove, the source electrode 10 is formed by evaporation at the second notch, and the gate electrode 9 is formed by evaporation at the gate dielectric layer corresponding to the first notch;

[0083] S8. Annealing the epitaxial wafer in an inert atmosphere.

[0084] Photodetectors made of transition metal sulfides are difficult to produce on a large scale. The present application has a complete and mature preparation process that can be mass-produced.

[0085] In this embodiment, in step S8 , the specific annealing operation is: annealing at 750° C. in a N 2 atmosphere for 30 minutes.

[0086] The present invention can be mass-produced. The presence of the PN junction in the present invention enables the gate voltage to regulate its photoelectric characteristics. By applying a positive gate voltage to the device, the light-to-dark current ratio of the UV detection can exceed 10 6 , and the device has an extremely fast rise time τ rise and decay time τ decay .

[0087] In actual application, the rise time τ rise Can be 1.34ms, decay time τ decay In addition, the photodetector’s responsivity can reach 37.99A / W, the external quantum efficiency can reach 12900%, and the specific detection rate D* can reach 7.28×10 12 Jones.

[0088] like Figure 9 As shown in the figure, it is a real photo of the ultraviolet photodetector with recessed gate MOS structure based on gallium nitride. Figure 10 As shown in FIG, the IV characteristic curve of the ultraviolet photodetector with recessed gate MOS structure based on gallium nitride is shown in FIG. Figure 11 As shown, it is the transfer curve of the GaN-based recessed gate MOS structure ultraviolet photodetector.

[0089] like Figure 12 As shown in FIG, it is the responsivity diagram of the ultraviolet photodetector with recessed gate MOS structure based on gallium nitride; Figure 13 As shown in the figure, it is the external quantum efficiency diagram of the ultraviolet photodetector with recessed gate MOS structure based on gallium nitride; Figure 14 As shown in FIG, it is a detection diagram of the ultraviolet photodetector with a recessed gate MOS structure based on gallium nitride; Figure 15 Shown is a light-to-dark current ratio diagram of a gallium nitride-based recessed gate MOS structure ultraviolet photodetector.

[0090] The above description is only a preferred embodiment of the present invention and does not limit the scope of patent protection of the present invention. Any equivalent structural transformation made by using the contents of the description and drawings of the present invention, directly or indirectly applied to other related technical fields, is also included in the scope of protection of the present invention.

Claims

1. A gallium nitride-based recessed gate MOS structure ultraviolet photodetector, characterized in that: include: substrate; a buffer layer, located on the upper surface of the substrate; First n + - a GaN layer located on the upper surface of the buffer layer; n - -GaN layer, located on the first n + - the upper surface of the GaN layer; The p-GaN layer is located on the n - - the upper surface of the GaN layer; Second n + -GaN layer, located on the upper surface of the p-GaN layer, the p-GaN layer and the second n + -GaN layer is formed on the - - a first recess on the surface of the GaN layer; The gate dielectric layer is located at the first n + -The upper surface of the GaN layer, the second n + -The upper surface of the GaN layer and the surface of the first recess, the gate dielectric layer, the second n + The -GaN layer and the p-GaN layer are formed with a second notch, and there are two second notches, one located on either side of the first notch; Two drain electrodes, located on the first n + -GaN layer, and respectively located on both sides of the gate dielectric layer; a gate electrode, located on an upper surface of the gate dielectric layer and corresponding to the first recess; as well as The two source electrodes are respectively located at the corresponding second notches.

2. The gallium nitride-based recessed gate MOS structure ultraviolet photodetector according to claim 1, wherein: The first n + -GaN layer thickness is 0.5μm -3 μm, the carrier concentration is 1×10 19 cm -3 -5×10 19 cm -3 .

3. The gallium nitride-based recessed gate MOS structure ultraviolet photodetector according to claim 1, wherein: The n - -GaN layer thickness ranges from 2μm to 8μm, and the carrier concentration is 1×10 16 cm -3 -5×10 16 cm -3 .

4. The gallium nitride-based recessed gate MOS structure ultraviolet photodetector according to claim 1, wherein: The thickness of the p-GaN layer is 1 μm-2 μm, and the carrier concentration is 5×10 17 cm -3 -1×10 18 cm -3 .

5. The gallium nitride-based recessed gate MOS structure ultraviolet photodetector according to claim 1, wherein: The second n + The thickness of the GaN layer is 0.1 μm-1 μm, and the carrier concentration is 1×10 19 cm -3 -5×10 19 cm -3 .

6. The gallium nitride-based recessed gate MOS structure ultraviolet photodetector according to claim 1, wherein: The substrate is a sapphire substrate; the gate dielectric layer is Al2O3.

7. A method for preparing a gallium nitride-based recessed gate MOS structure ultraviolet photodetector, characterized in that: The following steps are involved: S1, prepare the substrate, and deposit the buffer layer, the first n + -GaN layer, n - -GaN layer, p-GaN layer and the second n + -GaN layer to obtain epitaxial wafer; S2, etch the mesa of the epitaxial wafer so that the first n + -The GaN layer is partially exposed; S3, for the second n + -GaN layer and p-GaN layer are etched to obtain an extension to n - - a first recess in the GaN layer; S4, depositing a gate dielectric layer on the outer surface of the epitaxial wafer; S5, etching the gate dielectric layer located at the second n + -GaN layer, two first grooves are obtained, and two second grooves are located on both sides of the first groove. + -a gate dielectric layer above the GaN layer, to obtain two second grooves, the two second grooves being located on both sides of the gate dielectric layer; S6, etching the second n below the first groove + -GaN layer and p-GaN layer, the first groove and the space formed by etching together form a second notch, and there are two second notches, respectively located on both sides of the first notch; S7, evaporating to obtain a drain electrode at the second groove, evaporating to obtain a source electrode at the second notch, and evaporating to obtain a gate electrode at a position of the gate dielectric layer corresponding to the first notch; S8. Annealing the epitaxial wafer in an inert atmosphere.

8. The method for preparing a gallium nitride-based recessed gate MOS structure ultraviolet photodetector according to claim 7, wherein: The first n + The thickness of the GaN layer is 0.5 μm-3 μm, and the carrier concentration is 1×10 19 cm -3 -5×10 19 cm -3 ; said n - -GaN layer thickness ranges from 2μm to 8μm, and the carrier concentration is 1×10 16 cm -3 -5×10 16 cm -3 The thickness of the p-GaN layer is 1 μm-2 μm, and the carrier concentration is 5×10 17 cm -3 -1×10 18 cm -3 ; The second n + The thickness of the GaN layer is 0.1 μm-1 μm, and the carrier concentration is 1×10 19 cm -3 -5×10 19 cm -3 .

9. The method for preparing a gallium nitride-based recessed gate MOS structure ultraviolet photodetector according to claim 7, wherein: The substrate is a sapphire substrate; the gate dielectric layer is Al2O3.

10. The method for preparing a gallium nitride-based recessed gate MOS structure ultraviolet photodetector according to claim 7, wherein: In step S8, the specific operation of annealing is: annealing at 750° C. in a N 2 atmosphere for 30 minutes.

Images