Ultraviolet photoelectric detector and preparation method thereof

Abstract

The invention provides an ultraviolet photoelectric detector and a preparation method thereof. On the basis of a traditional beta-Ga2O3 detector, a Sn: beta-Ga2O3 / beta-Ga2O3 homogeneous structure is designed, SiO2 is deposited through PECVD to serve as a barrier layer, short-circuit contact between the second electrode and the first electrode is avoided, the excitation effect of ultraviolet light and Sn: beta-Ga2O3 is blocked, and therefore accurate response is achieved; then Ti / Au electrodes located on the surface and the bottom surface respectively are constructed, the vertical structure is more beneficial to integration of the device in a more complex and special environment, and the application range of the beta-Ga2O3 detector is greatly expanded; the on-off ratio of a single detection unit can reach 103, the response speed can reach ms level under 5V reverse bias, the responsivity can reach 350 A / W under 1V bias, and the specific detection rate can reach 5 * 10 < 13 > Jones.

Description

Technical Field

[0001] This invention relates to the field of photodetector technology, and in particular to an ultraviolet photodetector and its fabrication method. Background Technology

[0002] β-Ga2O3, as a fourth-generation semiconductor, possesses excellent optoelectronic properties, such as a bandgap that falls precisely in the ultraviolet band, extremely low resistance under high voltage, and excellent thermal and chemical stability. These characteristics make it widely applicable in photodetectors, high-frequency high-voltage devices, and other fields. Compared to other semiconductor homojunction photodetectors, β-Ga2O3, due to its perfect bandgap, can naturally shield against light interference in non-response bands. Its high-voltage and high-frequency resistance allows it to operate stably in more complex environments. However, the fabrication of β-Ga2O3 and the large-scale construction of homojunctions have always been core challenges for its applications. Homojunction construction can solve the problem of slow response rates caused by the low carrier mobility of β-Ga2O3. Large-scale array fabrication is a crucial step for β-Ga2O3 to move from research to practical application. Most research typically uses GaN, metal oxides, or two-dimensional materials to construct heterojunctions. While these methods can achieve certain electrical performance in single devices, they suffer from poor compatibility with large-scale processes, making array integration difficult and limiting large-scale applications. Therefore, developing a β-Ga2O3 homojunction array device with feasible technology and excellent performance is the key to promoting its industrial application. Summary of the Invention

[0003] To address the shortcomings of existing technologies, this invention provides an ultraviolet photodetector and its fabrication method. Based on a traditional β-Ga₂O₃ detector, this invention designs a Sn-doped β-Ga₂O₃ / β-Ga₂O₃ homogeneous structure. SiO₂ is deposited via PECVD as a barrier layer, which avoids short-circuit contact between the top electrode (i.e., the second electrode) and the Sn:β-Ga₂O₃ layer, and also blocks the excitation interaction between ultraviolet light and the Sn-doped β-Ga₂O₃, thus achieving precise response. Electrodes are then constructed on the surface and bottom, respectively. This vertical structure facilitates the integration of the device into more complex and specialized environments, greatly expanding the application range of β-Ga₂O₃.

[0004] To achieve the above-mentioned technical objectives, the present invention adopts the following technical solution:

[0005] In a first aspect, the present invention provides an ultraviolet photodetector, comprising:

[0006] First electrode;

[0007] A Sn-doped β-Ga2O3 layer is located on the surface of the first electrode;

[0008] An array of β-Ga2O3 layers is disposed on the Sn-doped β-Ga2O3 layer away from the surface of the first electrode.

[0009] A silicon dioxide layer is located on the surface of the Sn-doped β-Ga2O3 layer that is far from the first electrode and is not covered by the β-Ga2O3 layer.

[0010] The second electrode is arranged in an array on the surface of the silicon dioxide layer. The second electrode corresponds one-to-one with the β-Ga2O3 layer and is electrically connected to the β-Ga2O3 layer.

[0011] Preferably, the doping concentration of the Sn-doped β-Ga2O3 layer is 1×10⁻⁶. 18 ~1×10 19 cm -3 The thickness of the Sn-doped β-Ga2O3 layer is 400~800 μm.

[0012] Preferably, the thickness of the β-Ga2O3 layer is 200~400 nm;

[0013] The thickness of the silicon dioxide layer is 100~300nm;

[0014] The thickness of the first electrode is 20~150nm;

[0015] The thickness of the second electrode is 20~150nm.

[0016] Preferably, the material of the first electrode includes at least one of Ti and Au;

[0017] The material of the second electrode includes at least one of Ti and Au.

[0018] Secondly, the present invention also provides a method for preparing the aforementioned ultraviolet photodetector, comprising the following steps:

[0019] Deposit a β-Ga2O3 epitaxial layer on a Sn-doped β-Ga2O3 layer;

[0020] A first photoresist was coated on a β-Ga2O3 epitaxial layer, and the gallium oxide pattern was obtained by exposure and development through laser direct writing.

[0021] A hard mask Cr is deposited on the gallium oxide pattern, and then the first photoresist is removed, leaving the hard mask Cr.

[0022] The β-Ga2O3 epitaxial layer was etched by ICP-RIE process to remove the hard mask Cr, and an array of β-Ga2O3 layers was formed on the Sn-doped β-Ga2O3 layer.

[0023] Silicon dioxide was deposited on the surface of the Sn-doped β-Ga2O3 layer and on the surface of the β-Ga2O3 layer.

[0024] A second photoresist is coated on the silicon dioxide surface. The β-Ga2O3 layer is exposed and developed by laser direct writing. The second photoresist is used as a mask to etch the silicon dioxide deposited on the β-Ga2O3 layer to expose the β-Ga2O3 layer and remove the residual second photoresist.

[0025] A third photoresist was coated on the surface of the Sn-doped β-Ga2O3 layer and the β-Ga2O3 layer surface. After exposure and development by laser direct writing, the second electrode was deposited.

[0026] The first electrode is obtained by depositing on the surface of the Sn-doped β-Ga2O3 layer away from the β-Ga2O3 layer.

[0027] Preferably, the β-Ga2O3 epitaxial layer is etched by ICP-RIE process, and the etching process parameters are as follows: the etching gases are BCl3 and Ar, the BCl3 flow rate is 25 sccm, the Ar flow rate is 15 sccm, the pressure is 5~10 mTorr, the ICP power is 900W, and the RIE bias power is 90W.

[0028] Preferably, in the step of depositing a hard mask Cr on the gallium oxide pattern, the thickness of the hard mask Cr is 50~180nm.

[0029] Preferably, a β-Ga2O3 epitaxial layer is deposited on a Sn-doped β-Ga2O3 layer by MOCVD, specifically including: using triethylgallium and oxygen as reaction precursor gases, and argon as carrier gas, to deposit the β-Ga2O3 epitaxial layer; wherein, the triethylgallium gas flow rate is 70~80 sccm, the oxygen gas flow rate is 70~80 sccm, the argon gas flow rate is 1000~1100 sccm, the reaction chamber pressure is 30~80 Torr, and the growth temperature is 900~950℃.

[0030] Depositing a β-Ga2O3 epitaxial layer on a Sn-doped β-Ga2O3 layer specifically includes:

[0031] The ultraviolet photodetector and its fabrication method of the present invention have the following advantages compared with the prior art:

[0032] This invention fabricates a vertical Sn:β-Ga2O3 / β-Ga2O3 homojunction ultraviolet photodetector array using microfabrication technology. This array exhibits excellent uniformity, a regular homojunction unit structure, and superior electrical response. Each detection unit is independent, structurally regular, and possesses excellent uniformity, enabling ultraviolet signal detection for image recognition and other applications. Based on traditional β-Ga2O3 detectors, a Sn:β-Ga2O3 / β-Ga2O3 homojunction structure was designed, and SiO2 was deposited as a barrier layer via PECVD. This avoids short-circuit contact between the top electrode (i.e., the second electrode) and the Sn:β-Ga2O3 layer, and also blocks the excitation interaction between ultraviolet light and Sn:β-Ga2O3, thereby achieving precise response. Ti / Au electrodes were then constructed on the surface and bottom, respectively. This vertical structure is more conducive to the integration of the device into more complex and special environments, greatly expanding the application range of β-Ga2O3 detectors. Through multiple adjustments to parameters such as etching power and etching gas flow rate, this invention achieves a vertical etching cross-section, high selectivity, and low roughness, with a single detection unit on / off ratio reaching 10. 3 With a 5V reverse bias, the response speed can reach the millisecond level; with a 1V bias, the responsivity can reach 350 A / W and the specific detectivity can reach 5×10⁻⁶. 13 Jones is superior compared to similar homogeneous knots. Attached Figure Description

[0033] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0034] Figure 1 This is a schematic diagram of the structure of the ultraviolet photodetector of the present invention;

[0035] Figure 2 This is a schematic diagram of the fabrication process of the ultraviolet photodetector of the present invention;

[0036] Figure 3 A schematic diagram showing the formation of an 8×8 array of β-Ga2O3 layers on a Sn-doped β-Ga2O3 layer;

[0037] Figure 4 This is a photograph of the ultraviolet photodetector prepared in Example 1;

[0038] Figure 5 Scanning electron microscope (SEM) images of the β-Ga2O3 layers obtained after ICP-RIE etching in Examples 1 and 1-5;

[0039] Figure 6 The IV characteristic curve of the ultraviolet photodetector prepared in Example 1;

[0040] Figure 7 The IT curve of the ultraviolet photodetector prepared in Example 1 is a response graph of voltage variation.

[0041] Figure 8 The curves show the response speed and specific detectivity of the ultraviolet photodetector prepared in Example 1 under different voltages. Detailed Implementation

[0042] To facilitate understanding of the present invention, a more comprehensive description of the invention will be provided below in conjunction with specific embodiments. Preferred embodiments of the invention are given in the specific embodiments. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a thorough and complete understanding of the disclosure of the present invention.

[0043] The order in which the embodiments are described below is not intended to limit the preferred order of the embodiments. Furthermore, in the description of this application, the term "comprising" means "including but not limited to". Various embodiments of the invention may exist in the form of a range; it should be understood that the description in the form of a range is merely for convenience and brevity and should not be construed as a rigid limitation on the scope of the invention; therefore, it should be considered that the range description has specifically disclosed all possible sub-ranges and single numerical values ​​within that range. For example, it should be considered that the range description from 1 to 6 has specifically disclosed sub-ranges, such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., and single numbers within the range, such as 1, 2, 3, 4, 5, and 6, regardless of the range. Additionally, whenever a numerical range is indicated herein, it means including any referenced number (fraction or integer) within the indicated range.

[0044] This invention provides an ultraviolet photodetector, comprising:

[0045] First electrode 1;

[0046] Sn-doped β-Ga2O3 layer 2 is located on the surface of the first electrode 1;

[0047] β-Ga2O3 layer 4, which is arrayed on the surface of Sn-doped β-Ga2O3 layer 2 away from the first electrode 1;

[0048] The silicon dioxide layer 3 is located on the surface of the Sn-doped β-Ga2O3 layer 2 that is far from the first electrode 1 and is not covered by the β-Ga2O3 layer 4.

[0049] The second electrode 5 is arranged in an array on the surface of the silicon dioxide layer 3. The second electrode 5 corresponds one-to-one with the β-Ga2O3 layer 4 and is electrically connected to the β-Ga2O3 layer 4.

[0050] The ultraviolet photodetector of the present invention, such as Figure 1 As shown, the electrode includes a first electrode 1, a Sn-doped β-Ga₂O₃ layer 2, a silicon dioxide layer 3, a β-Ga₂O₃ layer 4, and a second electrode 5. The Sn-doped β-Ga₂O₃ layer 2 is located on the surface of the first electrode 1, and an array of β-Ga₂O₃ layers 4 is arranged on the surface of the Sn-doped β-Ga₂O₃ layer 2. For example, the array of β-Ga₂O₃ layers 4 can be arranged as 1×1, 1×2, 2×1, 2×2, 3×3, 4×4, 5×5, 6×6, 7×7, 8×8…, n×n (i.e., n β-Ga₂O₃ layers are arranged in each row and n β-Ga₂O₃ layers are arranged in each column). Partially covering the surface of Sn-doped β-Ga2O3 layer 2, a silicon dioxide layer 3 is disposed on the surface of Sn-doped β-Ga2O3 layer 2 that is not covered by β-Ga2O3 layer 4; a second electrode 5 is arrayed on the surface of silicon dioxide layer 3, and the second electrode 5 corresponds one-to-one with the β-Ga2O3 layer 4, that is, the number of second electrodes 5 and β-Ga2O3 layers 4 is the same. For a single second electrode 5, it is disposed on the surface of silicon dioxide layer 3 and one end extends to connect with the corresponding single β-Ga2O3 layer 4, thus forming a detection unit array, and the first electrode 1 is the bottom common electrode, and the detection unit array shares the first electrode 1;

[0051] This array exhibits excellent uniformity, a regular homojunction unit structure, and superior electrical response, with a single probe unit switching ratio reaching 10. 3 With a 5V reverse bias, the response speed can reach the millisecond level; with a 1V bias, the responsivity can reach 350 A / W and the specific detectivity can reach 5×10⁻⁶. 13 Jones, compared to similar homojunctions, is superior. The Sn-doped β-Ga2O3 / β-Ga2O3 homojunction ultraviolet photodetector array of this invention has great application value in fields such as phased array radar, space communication, medical ultraviolet detection, intelligent vehicles, high-voltage spark detection, and fire early warning devices.

[0052] In some embodiments, the doping concentration of the Sn-doped β-Ga2O3 layer 2 is 1×10⁻⁶. 18 ~1×10 19 cm -3 The thickness is 400~800 μm.

[0053] In some embodiments, the thickness of the β-Ga2O3 layer 4 is 200~400 nm.

[0054] In some embodiments, the thickness of the silicon dioxide layer 3 is 100~300nm.

[0055] In some embodiments, the thickness of the first electrode 1 is 20~150 nm;

[0056] The thickness of the second electrode 5 is 20~150nm.

[0057] In some embodiments, the material of the first electrode 1 includes at least one of Ti and Au. Preferably, the first electrode 1 is a Ti / Au electrode, with Au located on the Ti surface and Sn-doped β-Ga2O3 layer 2 located on the Au surface. The thickness of Ti is 20 nm and the thickness of Au is 100 nm.

[0058] The material of the second electrode 5 includes at least one of Ti and Au. Preferably, the second electrode 5 is a Ti / Au electrode, with Au located on the Ti surface and Ti located on the surface of the silicon dioxide layer 3. The thickness of Ti is 20 nm and the thickness of Au is 100 nm.

[0059] Specifically, the first electrode 1 and the second electrode 5 form ohmic contacts with the Sn-doped β-Ga2O3 layer 2 and the β-Ga2O3 layer 4, respectively, and both the first electrode 1 and the second electrode 5 are Ti / Au electrodes.

[0060] Based on the same inventive concept, the present invention also provides a method for preparing the above-mentioned ultraviolet photodetector, comprising the following steps:

[0061] S1. Deposit a β-Ga2O3 epitaxial layer on a Sn-doped β-Ga2O3 layer;

[0062] S2. Coat the first photoresist on the β-Ga2O3 epitaxial layer, expose and develop it by laser direct writing to obtain gallium oxide pattern;

[0063] S3. Deposit a hard mask Cr on the gallium oxide pattern, then remove the first photoresist, leaving the hard mask Cr;

[0064] S4. The β-Ga2O3 epitaxial layer is etched by ICP-RIE process to remove the hard mask Cr, and an array of β-Ga2O3 layers is formed on the Sn-doped β-Ga2O3 layer.

[0065] S5. Deposit silicon dioxide on the surface of the Sn-doped β-Ga2O3 layer and the surface of the β-Ga2O3 layer;

[0066] S6. Coat the silicon dioxide surface with a second photoresist, expose and develop the β-Ga2O3 layer by laser direct writing, use the second photoresist as a mask to etch the silicon dioxide deposited on the β-Ga2O3 layer to expose the β-Ga2O3 layer, and remove the residual second photoresist.

[0067] S7. Continue to coat the surface of the Sn-doped β-Ga2O3 layer with a third photoresist, expose and develop it by laser direct writing, and then deposit the second electrode.

[0068] S8. A first electrode is deposited on the surface of the Sn-doped β-Ga2O3 layer away from the β-Ga2O3 layer.

[0069] In some embodiments, a β-Ga2O3 epitaxial layer is prepared on a Sn-doped β-Ga2O3 layer by metal chemical vapor deposition (MOCVD), specifically including: using triethylgallium and oxygen as reaction precursor gases, and argon as carrier gas, to deposit a β-Ga2O3 epitaxial layer; wherein, the triethylgallium gas flow rate is 70~80 sccm, the oxygen gas flow rate is 70~80 sccm, the argon gas flow rate is 1000~1100 sccm, the reaction chamber pressure is 30~80 Torr, and the growth temperature is 900~950℃.

[0070] In some embodiments, the Sn-doped β-Ga2O3 layer can be a commercially available product or can be prepared using existing conventional methods. The specific preparation method is as follows: the Sn-doped β-Ga2O3 layer is epitaxially grown by MOCVD, then the epitaxial Sn-doped β-Ga2O3 layer is stripped by chemical etching, the stripped interface is polished by CMP technology, and then annealed at high temperature at 800 degrees Celsius to obtain the Sn-doped β-Ga2O3 layer.

[0071] In some embodiments, silicon dioxide is deposited on the surface of the Sn-doped β-Ga2O3 layer and the β-Ga2O3 layer using a plasma-enhanced chemical vapor deposition (PECVD) process.

[0072] In some embodiments, the method for fabricating an ultraviolet photodetector includes the following steps:

[0073] S1. A β-Ga2O3 epitaxial layer is deposited on the Sn-doped β-Ga2O3 layer by MOCVD. The thickness of the β-Ga2O3 epitaxial layer can be 200~400nm.

[0074] S2. Coat the first photoresist on the β-Ga2O3 epitaxial layer, expose and develop it using a laser direct writing system to obtain a gallium oxide pattern (the gallium oxide pattern is compatible with the β-Ga2O3 layer set in the array).

[0075] S3. Deposit a hard mask Cr on the gallium oxide pattern, then remove the first photoresist with acetone, leaving the hard mask Cr. The thickness of the Cr mask is 50~180nm.

[0076] S4. The β-Ga2O3 epitaxial layer is etched by ICP-RIE process to obtain gallium oxide structure. Then, the structure is cleaned with chemical etchant to remove the residual hard mask Cr. An array of β-Ga2O3 layers is formed on the Sn-doped β-Ga2O3 layer.

[0077] S5. Then, the sample etched in S4 is deposited with a silicon dioxide film on the surface of the Sn-doped β-Ga2O3 layer and the surface of the β-Ga2O3 layer by PECVD. The thickness of the silicon dioxide film is 100~300nm.

[0078] S6. Coat the surface of the silicon dioxide thin film with a second photoresist, and then expose and develop the β-Ga2O3 layer again using a laser direct writing overlay system.

[0079] S7. Using the second photoresist as a mask, etch the silicon dioxide deposited on the β-Ga2O3 layer until all SiO2 is etched away, exposing the β-Ga2O3 layer, and remove the remaining third photoresist.

[0080] S8. Continue to coat the surface of the Sn-doped β-Ga2O3 layer with a third photoresist, and expose and develop the β-Ga2O3 layer using a laser direct writing overlay system to obtain the second electrode pattern.

[0081] S9. A 20 / 100 nm thick Ti / Au electrode is deposited on the second electrode pattern using an electron beam evaporation deposition system. The third photoresist is then removed with acetone to obtain the second electrode.

[0082] S10. On the surface of the Sn-doped β-Ga2O3 layer away from the β-Ga2O3 layer, a 20 / 100 nm thick Ti / Au electrode is deposited using an electron beam evaporation deposition system, which is the first electrode.

[0083] In some embodiments, the β-Ga2O3 epitaxial layer is etched by ICP-RIE process. The etching process parameters are as follows: the etching gases are BCl3 and Ar, the BCl3 flow rate is 25 sccm, the Ar flow rate is 15 sccm, the pressure is 5~10 mTorr, the ICP power is 900W, the RIE bias power is 90W, and the etching temperature is 20~25℃.

[0084] In some embodiments, the first photoresist, the second photoresist, and the third photoresist may be ultraviolet photoresist AZ1500, photoresist AZ P4620, etc.

[0085] Further reference Figure 2The diagram illustrates the fabrication process of the ultraviolet photodetector of this invention. First, a Sn-doped β-Ga₂O₃ substrate of approximately 600 μm is obtained using the industrially mature Czochralski method. Then, a 300 nm β-Ga₂O₃ epitaxial layer is deposited on the Sn:β-Ga₂O₃ (i.e., the Sn-doped β-Ga₂O₃ layer) surface via MOCVD. Triethylgallium (70 sccm) and O₂ (70 sccm) are used as precursors, and Ar (1000 sccm) is used as the carrier gas. The reaction chamber pressure is 60 Torr, and the reaction temperature is 900 °C. Next, an ultraviolet photoresist AZ1500 is spin-coated onto the β-Ga₂O₃ epitaxial layer. After drying the photoresist, the β-Ga₂O₃ thin film pattern is exposed using an ultraviolet lithography system, and then developed and fixed using an organic solvent. Figure 2 As shown in (a) and (b); then, metallic Cr is deposited by electron beam evaporation as a hard mask, and excess photoresist is melted off, as shown in (b). Figure 2 As shown in (c). Subsequently, β-Ga2O3 was etched away in the ICP-RIE system, followed by the removal of the residual Cr mask using a chemical etching solution, as shown in... Figure 2 As shown in (d) and (e) in the diagram. A layer of SiO2 was then grown on the sample surface using PECVD. Photoresist was then applied to the sample again, dried, and a β-Ga2O3 thin film pattern was etched again. The pattern was then developed and fixed using an organic solvent. Finally, using the photoresist as a mask, the SiO2 on the surface of the β-Ga2O3 thin film pattern was etched away using an ICP-RIE system, as shown in the diagram. Figure 2 As shown in (f) and (g). The sample was then coated with photoresist again, and a TiAu top electrode pattern was photolithographically patterned. Subsequently, a Ti / Au electrode was deposited using an electron beam evaporation deposition system, as shown. Figure 2 As shown in Figure (h), photoresist is then applied again and dried as a protective layer for the previous structure. Then, a bottom common electrode (i.e., Ti / Au electrode, also known as the first electrode) is deposited on the bottom of the sample using an electron beam evaporation deposition system, as shown in Figure (i), and finally a complete device is obtained.

[0086] Further reference Figure 3 As shown, an 8×8 array of β-Ga2O3 layers (i.e., n β-Ga2O3 layers per row and n β-Ga2O3 layers per column) is formed on a Sn-doped β-Ga2O3 layer. The corresponding number of second electrodes is also 64, and there is a one-to-one correspondence between the β-Ga2O3 layer and the second electrode. Each β-Ga2O3 layer is electrically connected to a single second electrode.

[0087] This invention fabricates a vertical Sn:β-Ga2O3 / β-Ga2O3 homojunction ultraviolet photodetector array using microfabrication processes. This array exhibits excellent uniformity, a regular homojunction unit structure, and superior electrical response. Each detection unit is independent, structurally regular, and possesses excellent uniformity, enabling ultraviolet signal detection for image recognition and other applications. Based on traditional β-Ga2O3 detectors, a Sn:β-Ga2O3 / β-Ga2O3 homojunction structure was designed. SiO2 was deposited via PECVD as a barrier layer, preventing short-circuit contact between the top electrode (i.e., the second electrode) and the Sn:β-Ga2O3 layer, and also blocking the excitation interaction between ultraviolet light and Sn:β-Ga2O3, thus achieving precise response. Subsequently, TiAu electrodes were constructed on the surface and bottom. This vertical structure facilitates the integration of the device into more complex and specialized environments, greatly expanding the application range of β-Ga2O3 detectors.

[0088] This invention, through repeated adjustments to parameters such as etching power and etching gas flow rate, achieves a structure with a vertical etching cross-section, high selectivity, and low roughness, with a single probe unit on / off ratio reaching 10. 3 With a 5V reverse bias, the response speed can reach the millisecond level; with a 1V bias, the responsivity can reach 350 A / W and the specific detectivity can reach 5×10⁻⁶. 13 Jones is superior compared to similar homogeneous knots.

[0089] The following detailed embodiments further illustrate the ultraviolet photodetector and its fabrication method of the present invention. This section further explains the content of the present invention in conjunction with specific embodiments, but should not be construed as limiting the present invention. Unless otherwise specified, the technical means used in the embodiments are conventional means well known to those skilled in the art. Unless otherwise specified, the reagents, methods, and equipment used in the present invention are conventional reagents, methods, and equipment in the art.

[0090] Example 1

[0091] This embodiment provides an ultraviolet photodetector, including:

[0092] First electrode;

[0093] A Sn-doped β-Ga2O3 layer is located on the surface of the first electrode;

[0094] A β-Ga2O3 layer is arrayed on Sn-doped β-Ga2O3 layer 2 away from the surface of the first electrode.

[0095] The silicon dioxide layer is located on the surface of the Sn-doped β-Ga2O3 layer that is far from the first electrode and is not covered by the β-Ga2O3 layer.

[0096] The second electrode is arrayed on the surface of the silicon dioxide layer, and the second electrode corresponds one-to-one with the β-Ga2O3 layer and is electrically connected to the β-Ga2O3 layer.

[0097] The doping concentration of the Sn-doped β-Ga₂O₃ layer is 1×10⁻⁶. 19 cm -3 The Sn-doped β-Ga2O3 layer has a thickness of 800 μm;

[0098] The thickness of the β-Ga2O3 layer is 300 nm;

[0099] The silicon dioxide layer is 200 nm thick;

[0100] The first electrode is a Ti / Au electrode, with Au located on the Ti surface and a Sn-doped β-Ga2O3 layer located on the Au surface. The thickness of Ti is 20 nm and the thickness of Au is 100 nm.

[0101] The second electrode is a Ti / Au electrode, with Au located on the Ti surface and Ti located on the silicon dioxide layer surface. The thickness of Ti is 20 nm and the thickness of Au is 100 nm.

[0102] The β-Ga2O3 layers are arranged in an 8×8 array. The horizontal cross-section of a single β-Ga2O3 layer is rectangular, with a length of 200 μm and a width of 200 μm. The spacing between two adjacent β-Ga2O3 layers is 200 μm.

[0103] The above-mentioned method for fabricating an ultraviolet photodetector includes the following steps:

[0104] S1. A β-Ga2O3 epitaxial layer is deposited on a Sn-doped β-Ga2O3 layer (which is a commercially available product) by MOCVD. The thickness of the β-Ga2O3 epitaxial layer is 300 nm.

[0105] S2. Coat the first photoresist (specifically AZ1500) on the β-Ga2O3 epitaxial layer, expose and develop it using a laser direct writing system to obtain gallium oxide patterns;

[0106] S3. A hard mask Cr is deposited on the gallium oxide pattern, and then the first photoresist is removed by acetone leaching, leaving the hard mask Cr with a thickness of 150 nm. The hard mask Cr is deposited by magnetron sputtering, specifically using a Cr target as the target material, argon gas as the sputtering gas, a gas pressure of 0.5 Pa, and a sputtering power of 120 W. S4. The β-Ga2O3 epitaxial layer is etched by ICP-RIE process to obtain the gallium oxide structure. Then, the structure is cleaned with chemical etchant to remove the residual hard mask Cr, forming an array of β-Ga2O3 layers on the Sn-doped β-Ga2O3 layer.

[0107] S5. Subsequently, the etched sample from S4 is subjected to PECVD to deposit a silicon dioxide film on the surface of the Sn-doped β-Ga2O3 layer and the β-Ga2O3 layer. The thickness of the silicon dioxide film is 200 nm. The silicon dioxide film is deposited by plasma-enhanced chemical vapor deposition (PECVD). The controlled process parameters are: reaction gas: SiH4 (silicon source), N2O (oxygen source), gas flow rate: SiH4 60 sccm, N2O 250 sccm, RF power: 150 W, reaction chamber pressure: 15 Pa, deposition temperature: 250℃.

[0108] S6. Coat the surface of the silicon dioxide thin film with a second photoresist, and then expose and develop the β-Ga2O3 layer again using a laser direct writing overlay system.

[0109] S7. Using the second photoresist as a mask, etch the silicon dioxide deposited on the β-Ga2O3 layer until all SiO2 is etched away, exposing the β-Ga2O3 layer, and remove the remaining third photoresist.

[0110] S8. Continue to coat the surface of the Sn-doped β-Ga2O3 layer with a third photoresist, and expose and develop the β-Ga2O3 layer using a laser direct writing overlay system to obtain the second electrode pattern.

[0111] S9. A 20 / 100 nm thick Ti / Au electrode is deposited on the second electrode pattern using an electron beam evaporation deposition system. The third photoresist is then removed with acetone to obtain the second electrode.

[0112] S10. A 20 / 100 nm thick Ti / Au electrode, the first electrode, is deposited on the surface of the Sn-doped β-Ga₂O₃ layer away from the β-Ga₂O₃ layer using an electron beam evaporation deposition system. The Ti and Au in the first and second electrodes are prepared using the same method. The Ti is obtained by electron beam evaporation deposition, with the following specific process parameters: using a Ti target as the target material, and a vacuum degree of 3 × 10⁻⁶. -4 Pa, deposition rate 0.1 nm / s; Au was obtained by electron beam evaporation deposition, with specific process parameters as follows: Au target as the target material, vacuum degree 3 × 10⁻⁶. -4 Pa, deposition rate 0.2 nm / s;

[0113] Among them, the β-Ga2O3 epitaxial layer was etched by ICP-RIE process. The etching process parameters were: the etching gases were BCl3 and Ar, the BCl3 flow rate was 25 sccm, the Ar flow rate was 15 sccm, the pressure was 5 mTorr, the ICP power was 900W, the RIE bias power was 90W, and the etching temperature was 20℃.

[0114] A β-Ga2O3 epitaxial layer was deposited on a Sn-doped β-Ga2O3 layer using MOCVD. Specifically, the process involved using triethylgallium and oxygen as reaction precursor gases and argon as the carrier gas to deposit the β-Ga2O3 epitaxial layer. The flow rates of the triethylgallium gas, oxygen gas, and argon gas were 70 sccm, 70 sccm, and 1000 sccm, respectively. The reaction chamber pressure was 60 Torr, and the growth temperature was 900℃.

[0115] Comparative Example 1

[0116] The fabrication method of the ultraviolet photodetector provided in Comparative Example 1 is the same as that in Example 1, except that in step S4, the β-Ga2O3 epitaxial layer is etched by ICP-RIE process. The etching process parameters are as follows: the etching gases are BCl3 and Ar, the BCl3 flow rate is 25 sccm, the Ar flow rate is 15 sccm, the pressure is 5 mTorr, the ICP power is 600W, the RIE bias power is 120W, and the etching temperature is 20℃.

[0117] Comparative Example 2

[0118] The fabrication method of the ultraviolet photodetector provided in Comparative Example 2 is the same as that in Example 1, except that in step S4, the β-Ga2O3 epitaxial layer is etched by ICP-RIE process. The etching process parameters are as follows: the etching gases are BCl3 and Ar, the BCl3 flow rate is 25 sccm, the Ar flow rate is 15 sccm, the pressure is 5 mTorr, the ICP power is 600W, the RIE bias power is 90W, and the etching temperature is 20℃.

[0119] Comparative Example 3

[0120] The fabrication method of the ultraviolet photodetector provided in Comparative Example 3 is the same as that in Example 1, except that in step S4, the β-Ga2O3 epitaxial layer is etched by ICP-RIE process. The etching process parameters are as follows: the etching gases are BCl3 and Ar, the BCl3 flow rate is 35 sccm, the Ar flow rate is 5 sccm, the pressure is 5 mTorr, the ICP power is 900W, the RIE bias power is 90W, and the etching temperature is 20℃.

[0121] Comparative Example 4

[0122] The fabrication method of the ultraviolet photodetector provided in Comparative Example 4 is the same as that in Example 1, except that in step S4, the β-Ga2O3 epitaxial layer is etched by ICP-RIE process. The etching process parameters are as follows: the etching gases are BCl3 and Ar, the BCl3 flow rate is 30 sccm, the Ar flow rate is 10 sccm, the pressure is 5 mTorr, the ICP power is 900W, the RIE bias power is 90W, and the etching temperature is 20℃.

[0123] Comparative Example 5

[0124] The fabrication method of the ultraviolet photodetector provided in Comparative Example 5 is the same as that in Example 1, except that in step S4, the β-Ga2O3 epitaxial layer is etched by ICP-RIE process. The etching process parameters are as follows: the etching gases are BCl3 and Ar, the BCl3 flow rate is 20 sccm, the Ar flow rate is 20 sccm, the pressure is 5 mTorr, the ICP power is 900W, the RIE bias power is 90W, and the etching temperature is 20℃.

[0125] Performance testing

[0126] Figure 4 This is a physical image of the ultraviolet photodetector prepared in Example 1.

[0127] Figure 5 The images are scanning electron microscope (SEM) images of the β-Ga2O3 layers obtained after ICP-RIE etching in Examples 1 and 1-5; wherein, Figure 5 In the diagram, a, b, and c are scanning electron microscope (SEM) images of the β-Ga2O3 layer obtained after etching by the ICP-RIE process in Example 1; d is an SEM image of the β-Ga2O3 layer obtained after etching by the ICP-RIE process in Comparative Example 1; e is an SEM image of the β-Ga2O3 layer obtained after etching by the ICP-RIE process in Comparative Example 2; f is an SEM image of the β-Ga2O3 layer obtained after etching by the ICP-RIE process in Comparative Example 3; g is an SEM image of the β-Ga2O3 layer obtained after etching by the ICP-RIE process in Comparative Example 4; and h is an SEM image of the β-Ga2O3 layer obtained after etching by the ICP-RIE process in Comparative Example 5.

[0128] from Figure 5 As can be seen from the data, in Comparative Examples 1 and 2, adjusting the ICP / RIE power to 600 / 120W and 600 / 90W resulted in lower cross-sectional barrier perpendicularity of the β-Ga2O3 layer after etching compared to Example 1. In Comparative Examples 3 and 5, adjusting the BCl3 / Ar flow rate to 35 / 5sccm, 30 / 10sccm, and 20 / 20sccm also resulted in lower cross-sectional barrier perpendicularity of the β-Ga2O3 layer after etching compared to Example 1. This indicates that the optimal etching parameters in Example 1 of this invention are 25 sccm for BCl3 flow rate, 15 sccm for Ar flow rate, 600W for ICP power, and 120W for RIE bias power.

[0129] Figure 6 The IV characteristic curve of the ultraviolet photodetector prepared in Example 1;

[0130] Figure 7The IT curve of the ultraviolet photodetector prepared in Example 1 is a response graph of voltage variation.

[0131] Figure 8 The response speed and specific detectivity curves of the ultraviolet photodetector prepared in Example 1 at different voltages (-0.2V~1.4V) are shown.

[0132] Specifically, Figure 6 The test method is as follows: Under different light intensities (60 μW, 120 μW, 210 μW, 300 μW) of light from a 254nm light source, the IV curves of current versus voltage (the voltage applied between the second electrode and the first electrode, -1.5V to 1.5V) under various conditions were measured using a Keithley 4200 test system.

[0133] Figure 7 The testing method involves using a 254nm process (power 300μW / cm²). 2 The device was irradiated with a pulsed light source signal, and its IT response curve was measured as a function of voltage (-5V~5V) using a Keithley 4200 test system.

[0134] Figure 8 The responsivity and detectivity curves of the detector at different voltages (-0.2V~1.4V) are obtained based on the Keithley 4200 test system.

[0135] Depend on Figure 6-8 It can be concluded that, under a bias voltage of 1V (i.e., the voltage applied between the second electrode and the first electrode), the responsivity of a single cell reaches 350A / W, and the specific detectivity is 5×10⁻⁶. 13 Jones; Response time is 2ms under 5V reverse bias; Dark-state to light-state current ratio (switching ratio) reaches 10. 3 It exhibits excellent responsivity, detectivity, and response speed, with the response speed improving as the voltage increases. This makes it suitable for large-scale industrial production and applications, providing a new approach for the commercial application of gallium oxide ultraviolet detector arrays.

[0136] It is understood that the technical features of the above embodiments can be combined arbitrarily. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0137] The above are merely preferred embodiments of this application, and only specifically describe the technical principles of this application. These descriptions are only for explaining the principles of this application and should not be construed as limiting the scope of protection of this application in any way. Based on this explanation, any modifications, equivalent substitutions, and improvements made within the spirit and principles of this application, as well as other specific embodiments of this application that can be conceived by those skilled in the art without creative effort, should be included within the scope of protection of this application.

Claims

1. An ultraviolet photodetector, characterized in that, include: First electrode; A Sn-doped β-Ga2O3 layer is located on the surface of the first electrode; An array of β-Ga2O3 layers is disposed on the Sn-doped β-Ga2O3 layer away from the surface of the first electrode. A silicon dioxide layer is located on the surface of the Sn-doped β-Ga2O3 layer that is far from the first electrode and is not covered by the β-Ga2O3 layer. The second electrode is arranged in an array on the surface of the silicon dioxide layer. The second electrode corresponds one-to-one with the β-Ga2O3 layer and is electrically connected to the β-Ga2O3 layer.

2. The ultraviolet photodetector as described in claim 1, characterized in that, The doping concentration of the Sn-doped β-Ga2O3 layer is 1×10⁻⁶. 18 ~1×10 19 cm -3 The thickness of the Sn-doped β-Ga2O3 layer is 400~800 μm.

3. The ultraviolet photodetector as described in claim 1, characterized in that, The thickness of the β-Ga2O3 layer is 200~400nm; The thickness of the silicon dioxide layer is 100~300nm; The thickness of the first electrode is 20~150nm; The thickness of the second electrode is 20~150nm.

4. The ultraviolet photodetector as described in claim 1, characterized in that, The material of the first electrode includes at least one of Ti and Au; The material of the second electrode includes at least one of Ti and Au.

5. A method for fabricating an ultraviolet photodetector as described in claim 1, characterized in that, Includes the following steps: Deposit a β-Ga2O3 epitaxial layer on a Sn-doped β-Ga2O3 layer; A first photoresist was coated on a β-Ga2O3 epitaxial layer, exposed and developed to obtain a gallium oxide pattern; A hard mask Cr is deposited on the gallium oxide pattern, and then the first photoresist is removed, leaving the hard mask Cr. The β-Ga2O3 epitaxial layer was etched by ICP-RIE process to remove the hard mask Cr, and an array of β-Ga2O3 layers was formed on the Sn-doped β-Ga2O3 layer. Silicon dioxide was deposited on the surface of the Sn-doped β-Ga2O3 layer and on the surface of the β-Ga2O3 layer. A second photoresist is coated on the silicon dioxide surface, and the β-Ga2O3 layer is exposed and developed. Using the second photoresist as a mask, the silicon dioxide deposited above the β-Ga2O3 layer is etched to expose the β-Ga2O3 layer and remove the residual second photoresist. The third photoresist was coated on the surface of the Sn-doped β-Ga2O3 layer and the β-Ga2O3 layer, and then exposed and developed before deposition to obtain the second electrode. The first electrode is obtained by depositing on the surface of the Sn-doped β-Ga2O3 layer away from the β-Ga2O3 layer.

6. The method for fabricating an ultraviolet photodetector as described in claim 5, characterized in that, The β-Ga2O3 epitaxial layer was etched using an ICP-RIE process. The etching parameters were as follows: the etching gases were BCl3 and Ar, the BCl3 flow rate was 25 sccm, the Ar flow rate was 15 sccm, the pressure was 5~10 mTorr, the ICP power was 900W, and the RIE bias power was 90W.

7. The method for fabricating an ultraviolet photodetector as described in claim 5, characterized in that, In the step of depositing a hard mask Cr on a gallium oxide pattern, the thickness of the hard mask Cr is 50~180 nm.

8. The method for fabricating an ultraviolet photodetector as described in claim 5, characterized in that, A β-Ga2O3 epitaxial layer was deposited on a Sn-doped β-Ga2O3 layer by MOCVD. Specifically, the process involved using triethylgallium and oxygen as reaction precursor gases and argon as the carrier gas to deposit the β-Ga2O3 epitaxial layer. The flow rates of the triethylgallium gas and oxygen gas were 70-80 sccm, the flow rates of the oxygen gas and argon gas were 1000-1100 sccm, the reaction chamber pressure was 30-80 Torr, and the growth temperature was 900-950℃.

Images