Ultraviolet detector and method of manufacturing the same
Patent Information
- Application Number
- CN202611143396.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-07-30
- Publication Date
- 2026-09-25
AI Technical Summary
氧化镓（Ga2O3）虽具有4.9eV带隙优势，但其器件常面临响应速度与光响应度难以兼顾、暗电流较大、信噪比低等问题，且本征n型导电性限制了同质结结构
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Figure CN122825533A_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of photodetector technology, and in particular to an ultraviolet detector and its fabrication method. Background Technology
[0002] Ultraviolet (UV) detection has significant application value in multiple fields due to its unique optical properties. Traditional silicon carbide (SiC) and gallium nitride (GaN) materials require additional filters due to their narrow band gaps, increasing costs and reducing sensitivity. While gallium oxide (Ga2O3) boasts a 4.9 eV band gap advantage, its devices often face challenges such as difficulty in balancing response speed and photoresponsivity, high dark current, and low signal-to-noise ratio. Furthermore, its intrinsic n-type conductivity limits homojunction structures. Introducing nickel oxide (NiO) to construct heterojunctions still results in unsatisfactory carrier separation and transport efficiency, affecting the overall performance of the detector. Summary of the Invention
[0003] This application provides an ultraviolet detector and its fabrication method, aiming to increase the separation and collection efficiency of photogenerated carriers, reduce dark current, and improve device responsivity and photo-dark current ratio.
[0004] To achieve the above objectives, the embodiments of this application adopt the following technical solutions: In one aspect, an ultraviolet detector is provided, comprising a first semiconductor layer, a second semiconductor layer, a quantum tunneling layer, a first electrode layer, and a second electrode layer.
[0005] The first semiconductor layer is made of nickel oxide; a second semiconductor layer is stacked on top of the first semiconductor layer; the second semiconductor layer is made of gallium oxide; the first and second semiconductor layers have different doping types; a quantum tunneling layer is stacked between the first and second semiconductor layers; a first electrode layer is disposed on the side of the first semiconductor layer away from the quantum tunneling layer; a second electrode layer is disposed on the side of the second semiconductor layer away from the quantum tunneling layer. The side of the second semiconductor layer closest to the quantum tunneling layer has a built-in electric field, the direction of which is from the second semiconductor layer towards the quantum tunneling layer.
[0006] In the ultraviolet detector provided in this application embodiment, by introducing a quantum tunneling layer between the first semiconductor layer and the second semiconductor layer, and setting a built-in electric field on the side of the second semiconductor layer near the quantum tunneling layer, the direction of the built-in electric field is from the second semiconductor layer to the quantum tunneling layer, which can increase the separation and collection efficiency of photogenerated carriers, reduce dark current, and improve the device responsivity and photo-dark current ratio.
[0007] In some embodiments, the strength of the built-in electric field is 10. 5 ~10 6 V / cm.
[0008] In some embodiments, the second semiconductor layer has a gradient structure that extends from the surface of the second semiconductor layer near the quantum tunneling layer into the interior of the second semiconductor layer; from the interface between the gradient structure and the quantum tunneling layer to the surface of the gradient structure away from the quantum tunneling layer, the oxygen vacancy concentration of the gradient structure varies from 10... 18 ~5×10 18 cm -3 Gradually decrease to 10 17 ~5×10 17 cm -3 To create a built-in electric field.
[0009] In some embodiments, the ratio of the thickness of the second semiconductor layer to the thickness of the gradient structure is 2 to 4:1.
[0010] In some embodiments, the second semiconductor layer is indium doped; the concentration of indium doping does not exceed 5 at%.
[0011] In some embodiments, the material of the quantum tunneling layer includes hexagonal boron nitride; the thickness of the quantum tunneling layer is 2 nm to 5 nm.
[0012] In some embodiments, the material of the second semiconductor layer includes amorphous gallium oxide or crystalline gallium oxide.
[0013] In a second aspect, a method for fabricating an ultraviolet detector is provided, the method comprising: forming a second semiconductor layer; forming a quantum tunneling layer on the second semiconductor layer; forming a first semiconductor layer on the quantum tunneling layer; forming a first electrode layer on the side of the first semiconductor layer away from the quantum tunneling layer; and forming a second electrode layer on the side of the second semiconductor layer away from the quantum tunneling layer.
[0014] The second semiconductor layer is made of gallium oxide; one side surface of the second semiconductor layer has a built-in electric field. A quantum tunneling layer is stacked on the side surface of the second semiconductor layer with the built-in electric field; the direction of the built-in electric field is from the second semiconductor layer to the quantum tunneling layer. The first semiconductor layer is made of nickel oxide; the first and second semiconductor layers have different doping types.
[0015] In some embodiments, the second semiconductor layer includes a gradient structure located on the side of the second semiconductor layer near the quantum tunneling layer. During the formation of the second semiconductor layer, the oxygen vacancy concentration is controlled from 1 × 10⁻⁶ to a controlled value. 17 ~5×10 17 cm -3 Increased to 1×10 18 ~5×10 18 cm -3 To form the gradient structure.
[0016] In some embodiments, in the above preparation method, the second semiconductor layer has indium doping, and the concentration of indium doping does not exceed 5 at. Attached Figure Description
[0017] To more clearly illustrate the technical solutions in this application, the accompanying drawings used in some embodiments of this application will be briefly described below. Obviously, the drawings described below are only drawings of some embodiments of this application, and those skilled in the art can obtain other drawings based on these drawings. In addition, the drawings described below can be regarded as schematic diagrams and are not actual dimensions of the products or actual processes of the methods involved in the embodiments of this application.
[0018] Figure 1 A cross-sectional view of an ultraviolet detector provided in an embodiment of this application; Figure 2 A band structure diagram of an ultraviolet detector provided in an embodiment of this application; Figure 3 A flowchart for fabricating an ultraviolet detector provided in this application embodiment; Figures 4A to 4D The diagram shows the steps involved in fabricating an ultraviolet detector, as provided in the embodiments of this application. Detailed Implementation
[0019] The technical solutions in some embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments provided in this application are within the scope of protection of this application.
[0020] In the description of this application, it should be understood that the terms "center", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or structure referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.
[0021] Unless the context otherwise requires, throughout the specification and claims, the term "comprising" is interpreted as "including, but not limited to," "including." In the description of the specification, terms such as "one embodiment," "some embodiments," "exemplary embodiment," "exemplary," or "some examples," etc., are intended to indicate that a particular feature, structure, material, or characteristic associated with that embodiment or example is included in at least one embodiment or example of this application. The illustrative representations of the foregoing terms do not necessarily refer to the same embodiment or example. Furthermore, the foregoing particular features, structures, materials, or characteristics may be included in any suitable manner in any one or more embodiments or examples.
[0022] The terms "first," "second," etc., are used for descriptive and distinguishing purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of the embodiments of this application, unless otherwise stated, "a plurality of" means two or more.
[0023] As used herein, “parallel,” “perpendicular,” and “equal” include the described situation and situations that are similar to the described situation, within an acceptable deviation range, which is determined by those skilled in the art taking into account the measurement under discussion and the errors associated with the measurement of a particular quantity (i.e., the limitations of the measurement system). For example, “parallel” includes absolute parallelism and approximate parallelism, where an acceptable deviation range for approximate parallelism may be, for example, within 5°; “perpendicular” includes absolute perpendicularity and approximate perpendicularity, where an acceptable deviation range for approximate perpendicularity may also be, for example, within 5°; “equal” includes absolute equality and approximate equality, where an acceptable deviation range for approximate equality may be, for example, a difference between the two equals being less than or equal to 5% of either one.
[0024] Exemplary embodiments or examples are described herein with reference to the accompanying drawings, which are intended as idealized exemplary models. In the drawings, the thickness of layers and regions is enlarged for clarity. Therefore, variations in shape relative to the drawings are contemplated due to factors such as manufacturing techniques and / or tolerances. Thus, exemplary embodiments should not be construed as limited to the shapes of the regions shown herein, but rather include shape deviations due to factors such as manufacturing. Therefore, the regions shown in the drawings are schematic in nature, and their shapes are not intended to show the actual shapes of the regions of the device, nor are they intended to limit the scope of the exemplary embodiments.
[0025] Furthermore, the scenarios described in the embodiments of this application are for the purpose of more clearly illustrating the technical solutions of the embodiments of this application, and do not constitute a limitation on the technical solutions provided in the embodiments of this application. As those skilled in the art will know, with the emergence of new scenarios, the technical solutions provided in the embodiments of this application are also applicable to similar technical problems.
[0026] See Figure 1 This application provides an ultraviolet detector 100, which includes a first semiconductor layer 1, a second semiconductor layer 2, a quantum tunneling layer 3, a first electrode layer 4, and a second electrode layer 5.
[0027] The second semiconductor layer 2 is stacked with the first semiconductor layer 1, the quantum tunneling layer 3 is stacked between the first semiconductor layer 1 and the second semiconductor layer 2, the first electrode layer 4 is disposed on the side of the first semiconductor layer 1 away from the quantum tunneling layer 3, and the second electrode layer 5 is disposed on the side of the second semiconductor layer 2 away from the quantum tunneling layer 3. In other words, the ultraviolet detector 100 provided in some embodiments of this application includes the first electrode layer 4, the first semiconductor layer 1, the quantum tunneling layer 3, the second semiconductor layer 2, and the second electrode layer 5 disposed sequentially.
[0028] The first semiconductor layer 1 is made of nickel oxide (NiO), which, as an intrinsic p-type wide-bandgap semiconductor material, has a bandgap of 3.6 eV to 4.0 eV. The second semiconductor layer 2 is made of gallium oxide (Ga2O3), such as In-doped Ga2O3 (In:Ga2O3). Gallium oxide, as an ultra-wide bandgap semiconductor material, has a bandgap of 4.8 eV to 4.9 eV and high photoelectric response characteristics in the solar-blind band.
[0029] Furthermore, the first semiconductor layer 1 and the second semiconductor layer 2 have different doping types, forming a pn heterojunction. For example, the first semiconductor layer 1 is p-type doped with NiO, which is hole-type, and can collect and transport photogenerated holes; the second semiconductor layer 2 is n-type doped with Ga2O3, which is electron-type, and is used to collect and transport photogenerated electrons.
[0030] When the ultraviolet detector 100 receives light, the pn heterojunction generates photoelectrons and photoholes. The photoelectrons migrate towards the second semiconductor layer 2 and are eventually collected by the second electrode layer 5. The photoholes migrate towards the first semiconductor layer 1 and are eventually collected by the first electrode layer 4, thereby collecting the photocurrent through the first electrode layer 4 and the second electrode layer 5.
[0031] For example, an ohmic contact is formed between the first electrode layer 4 and the first semiconductor layer 1, and an ohmic contact is formed between the second electrode layer 5 and the second semiconductor layer 2, wherein the hole concentration in the first semiconductor layer 1 can be 1×10⁻⁶.18 cm -3 The electron concentration in the second semiconductor layer 2 can be 5 × 10⁻⁶. 17 cm -3 This carrier concentration helps to reduce the contact resistance between the electrode and the semiconductor layer and improve the carrier collection efficiency.
[0032] See Figure 2 The horizontal dashed line represents the Fermi level Ef. The two solid lines on the left represent the conduction band bottom Ec and valence band top Ev of NiO, respectively. At the heterojunction interface, the conduction band bottom and valence band top undergo downward band bending. The two solid lines on the right represent the conduction band bottom Ec and valence band top Ev of In:Ga2O3, respectively. At the heterojunction interface, the conduction band bottom and valence band top undergo upward band bending, forming the corresponding potential barrier region.
[0033] It is evident that the conduction band bottom (Ec) of In:Ga2O3 is lower than that of NiO, while the valence band top (Ev) of NiO is higher than that of In:Ga2O3. The conduction band bottom and valence band top are interleaved, forming a type II band structure (interleaved gap) between In:Ga2O3 and NiO. After photoexcitation, photogenerated electrons flow to the lower energy level of the conduction band (In:Ga2O3), while photogenerated holes flow to the higher energy level of the valence band (NiO). This achieves efficient separation and transport of photogenerated carriers (photogenerated electrons and photogenerated holes) and effectively suppresses carrier recombination, which is beneficial for improving the response speed and sensitivity of the ultraviolet detector 100.
[0034] Continue reading Figure 1 The second semiconductor layer 2 has a built-in electric field on the side near the quantum tunneling layer 3. The direction of this built-in electric field is from the second semiconductor layer 2 to the quantum tunneling layer 3, which can drive photogenerated electrons to migrate in the opposite direction of the built-in electric field (towards the second electrode layer 5), thus promoting carrier separation. At the same time, this built-in electric field gives the photogenerated carriers a high drift velocity, enabling them to be separated rapidly after generation. The separation time can be compressed to the picosecond level, which significantly suppresses radiative recombination and defect recombination of carriers at the source, thereby improving the collection efficiency of photogenerated carriers and ensuring that the ultraviolet detector 100 obtains high responsivity.
[0035] See again Figure 1 A quantum tunneling layer 3 is provided between the first semiconductor layer 1 and the second semiconductor layer 2, that is, a quantum tunneling layer 3 is introduced into the type II band arrangement structure. The quantum tunneling layer 3 allows quantum tunneling transport of photogenerated carriers. Furthermore, the quantum tunneling layer 3 can effectively suppress interface leakage current under reverse bias, significantly reduce dark current, improve signal-to-noise ratio, and thus improve the sensitivity of the ultraviolet detector 100.
[0036] In some embodiments, the material of the second semiconductor layer 2 includes amorphous gallium oxide, which can be directly deposited at low temperatures without the need for high-temperature annealing, thereby simplifying the preparation process, reducing manufacturing costs, and avoiding thermal diffusion and performance degradation that may be caused by high-temperature heat treatment to the quantum tunneling layer 3 and the heterojunction interface.
[0037] Furthermore, in the amorphous state, the concentration of Ga-O bonds can be precisely altered by controlling the O / Ga ratio. A reduction in Ga-O bonds introduces impurity energy levels near the conduction band bottom, lowering the conduction band bottom energy. Additionally, a reduction in O 2p orbital electrons lowers the valence band top energy. This optimizes the band gap and band curvature at the interface of the second semiconductor layer 2, further enhancing the separation efficiency of photogenerated carriers and effectively improving device responsivity and the photocurrent-to-dark-current ratio.
[0038] In other embodiments, the material of the second semiconductor layer 2 may also include crystalline gallium oxide, which has high crystal quality and excellent carrier mobility, which is beneficial for obtaining stable electrical performance and high response speed, and can ensure good repeatability and reliability under mature processes.
[0039] As mentioned above, in some embodiments, the second semiconductor layer 2 has indium doping, i.e., an In:Ga2O3 layer. Indium doping increases the Fermi level difference between the n-type second semiconductor layer 2 (In:Ga2O3) and the p-type first semiconductor layer 1 (NiO), making the band bending at the heterojunction interface more intense, thereby significantly enhancing the built-in electric field strength, providing a stronger separation driving force for photogenerated carriers, suppressing carrier recombination from the source, and realizing efficient separation of photogenerated carriers.
[0040] Furthermore, indium doping can fine-tune the electron affinity of the second semiconductor layer 2, optimizing the conduction band offset (ΔE) with the first semiconductor layer 1. C This facilitates smoother injection of photogenerated electrons into the conduction band of the second semiconductor layer 2 (In:Ga2O3), reduces carrier accumulation and recombination at the interface, and makes the establishment and dissipation of photogenerated current more rapid.
[0041] In addition, indium doping effectively reduces the resistivity of the second semiconductor layer 2, resulting in less scattering and recombination loss of the separated photogenerated electrons during transmission, thereby further improving the collection and transmission efficiency of charge carriers.
[0042] It is important to note that the indium doping concentration should preferably not exceed 5 at%, for example, indium doping concentrations of 5 at%, 4 at%, 3 at%, 1 at%, or 0.5 at. By doping the second semiconductor layer 2 (In:Ga2O3) with no more than 5 at%, its Fermi level and carrier concentration can be effectively controlled, thereby optimizing device performance in multiple aspects, further achieving efficient separation and transport of photogenerated carriers, and further improving the response speed and sensitivity of the ultraviolet detector 100.
[0043] In addition to optimizing the doping concentration of In in the second semiconductor layer 2, the photoelectric performance of the detector can also be precisely controlled by optimizing the thickness of the second semiconductor layer 2, as well as the thickness and hole concentration of the NiO layer. This effectively solves the problems caused by insufficient quality and stability of p-type nickel oxide quantum dot preparation in the existing technology.
[0044] In some embodiments, see Figure 1 In the second semiconductor layer 2, the intensity range of the built-in electric field can be 10. 5 V / cm~10 6 V / cm, for example, the strength of the built-in electric field can be 1.0 × 10⁻⁶. 5 V / cm, 1.2×10 5 V / cm, 5.5×10 5 V / cm, 8.0×10 5 V / cm, 1.0×10 6 V / cm, etc. The electric field within this intensity range is sufficient to compress the carrier separation time to the picosecond level, giving the carriers a sufficiently high drift velocity, ensuring that photogenerated carriers can be collected by the electrodes in a very short time, thereby enabling the ultraviolet detector 100 to have a fast response speed, meeting the application requirements of real-time monitoring and high-frequency dynamic response in the field of ultraviolet detection.
[0045] In some embodiments, see Figure 1 The built-in electric field in the second semiconductor layer 2 is formed by setting a gradient distribution of oxygen vacancy concentration. Specifically, the second semiconductor layer 2 has a gradient structure 21, which extends from the surface of the second semiconductor layer 2 near the quantum tunneling layer 3 into the interior of the second semiconductor layer 2. At the interface P1 between the gradient structure 21 and the quantum tunneling layer 3, the oxygen vacancy concentration can be in the range of 10. 18 ~5×10 18 cm -3 On the surface P2 of the gradient structure 21, which is far from the quantum tunneling layer 3, the oxygen vacancy concentration can range from 10. 17 ~5×10 17 cm -3 .
[0046] Furthermore, from interface P1 to surface P2, that is, along the direction away from quantum tunneling layer 3, the oxygen vacancy concentration in gradient structure 21 gradually decreases, for example, from 1×10 18 ~5×10 18 cm -3 Gradually reduce to 1×10 17 ~5×10 17 cm -3 .
[0047] like Figure 2 As shown, the two dashed lines on the right represent the conduction band bottom Ec and valence band top Ev of In:Ga2O3 without the gradient structure 21, respectively. The two solid lines on the right represent the conduction band bottom Ec and valence band top Ev of In:Ga2O3 with the gradient structure 21, respectively. It can be seen that after introducing the gradient structure 21, the energy band of In:Ga2O3 bends near the interface. For example, when the thickness of the gradient structure 21 (i.e., the dimension in the third direction Z) is 50 nm, the conduction band drops by at least 0.6 eV within a 50 nm range near the interface (the interface between the quantum tunneling layer 3 and the second semiconductor layer 2) (compared to the conduction band without the gradient structure 21), thus establishing an intensity of approximately 1.2 × 10⁻⁶. 5 Built-in electric field of V / cm.
[0048] It is worth noting that the strength of the built-in electric field can be adjusted by varying the gradient distribution of oxygen vacancy concentration in the second semiconductor layer 2. Furthermore, obtaining the built-in electric field by setting an oxygen vacancy concentration gradient distribution in the second semiconductor layer 2 is merely one exemplary implementation of the built-in electric field in this application. Any structural modifications or equivalent substitutions that achieve the aforementioned technical features of the built-in electric field fall within the scope of protection of this application, and are not limited to the specific numerical value of the oxygen vacancy concentration or the specific form of the gradient distribution, nor are they limited to the specific method of implementing the built-in electric field.
[0049] In some embodiments, see Figure 1 The maximum concentration of oxygen vacancies in the second semiconductor layer 2 is less than 1 × 10⁻⁶. 20 cm -3 For example, the maximum concentration of oxygen vacancies in the second semiconductor layer 2 is 5 × 10⁻⁶ as mentioned above. 18 cm -3 Increasing the oxygen vacancy concentration within a certain range can further enhance the built-in electric field strength and promote photogenerated carrier separation. However, when the oxygen vacancy concentration reaches or exceeds a critical value, it may cause prolonged residual conductivity, increase recombination centers leading to decreased device responsivity, or even cause metallization of the material, resulting in complete device failure. This embodiment controls the oxygen vacancy concentration at 1×10⁻⁶. 20 cm -3The following measures ensure that the device obtains a sufficient built-in electric field to enhance the separation efficiency of photogenerated carriers, while effectively avoiding the aforementioned negative effects.
[0050] In some embodiments, see Figure 1 The ratio of the thickness of the second semiconductor layer 2 to the thickness of the gradient structure 21 is (2-4):1. For example, the thickness of the second semiconductor layer 2 is 150 nm, and the thickness of the gradient structure 21 is 50 nm, meaning the ratio is 3:1. This ratio is appropriate; the thickness of the second semiconductor layer 2 is sufficient to ensure adequate light absorption and avoid insufficient responsivity. Simultaneously, the thickness of the gradient structure 21 provides a sufficient electric field driving range without increasing the carrier transport distance or causing attenuation of the far-end electric field due to excessive thickness. This achieves a good balance between light absorption efficiency and carrier collection efficiency, enabling the ultraviolet detector 100 to achieve optimal responsivity and response speed. Furthermore, the intensity of the built-in electric field can be adjusted by adjusting the thickness of the gradient structure 21.
[0051] In some embodiments, the material of the quantum tunneling layer 3 includes hexagonal boron nitride (h-BN). Utilizing the wide bandgap (approximately 5.9 eV) and atomically flat properties of hexagonal boron nitride, a high-quality, low-defect heterostructure interface can be formed between the first semiconductor layer 1 and the second semiconductor layer 2, effectively passivating the interface dangling bonds, thereby suppressing the formation of interface recombination and leakage channels at the source and significantly reducing dark current.
[0052] The quantum tunneling layer 3 should not be too thick, for example, 2nm to 5nm. For instance, the thickness of the quantum tunneling layer 3 can be 2nm, 3nm, 3.5nm, 4nm, or 5nm. By setting the quantum tunneling layer 3 within this thickness range, photogenerated carriers can efficiently pass through the potential barrier via quantum tunneling, reducing dark current while maintaining photoresponsivity, thereby improving the signal-to-noise ratio and enhancing the overall performance of the detector. For example, with a quantum tunneling layer 3 thickness of 3nm, the quantum tunneling probability of dark current can be reduced to 10-1. -15 The photogenerated carriers can still tunnel through effectively, which greatly increases the photocurrent-to-dark current ratio and further improves the signal-to-noise ratio of the device.
[0053] Based on the hole concentration setting in the first semiconductor layer 1, and combined with semiconductor band theory and carrier theory, a heterogeneous interface (e.g., NiO / h-BN) is formed between the first semiconductor layer 1 and the quantum tunneling layer 3, with a band bending height of approximately 0.6 eV at the interface; a heterogeneous interface (e.g., h-BN / In:Ga2O3) is formed between the quantum tunneling layer 3 and the second semiconductor layer 2, with a band bending height of approximately 0.3 eV to 0.4 eV at the interface.
[0054] Some embodiments of this application also provide a method for fabricating an ultraviolet detector. Figure 3 A flowchart for fabricating an ultraviolet detector provided in this application embodiment; Figures 4A to 4D The diagram shows the steps involved in fabricating an ultraviolet detector, as provided in the embodiments of this application.
[0055] like Figure 3 As shown, the fabrication method of the ultraviolet detector includes the following steps S1 to S4: S1: See Figure 4A A second semiconductor layer 2 is formed. The second semiconductor layer 2 has a built-in electric field on one side surface, that is, a built-in electric field is formed on the side of the second semiconductor layer 2 near the quantum tunneling layer 3 to be formed subsequently.
[0056] For example, a second semiconductor layer 2 (In:Ga2O3 layer) with indium doping can be prepared by pulsed laser deposition (PLD) process. The thickness of the second semiconductor layer 2 is approximately 150 nm, the substrate temperature is 650 °C, and the oxygen partial pressure is 2 × 10⁻⁶. -3 Pa to 5×10 -4 Dynamic adjustment within the Pa range.
[0057] For example, see Figure 4A The second semiconductor layer 2 may include a main body 20 and a gradient structure 21. Step S1, forming the second semiconductor layer 2, includes forming the main body 20 and the gradient structure 21 using the same process, but with different oxygen partial pressures at which the main body 20 and the gradient structure 21 are formed. The oxygen partial pressure during the formation of the gradient structure 21 gradually decreases along the direction approaching the quantum tunneling layer 3, thereby causing the oxygen vacancy concentration to gradually increase along this direction (i.e., the highest concentration at interface P1). This gradient structure 21 can be achieved through processes such as dynamically adjusting the oxygen partial pressure during film formation, thus exhibiting good process compatibility.
[0058] For example, during sputtering, the oxygen partial pressure is controlled to decrease from 2 × 10⁻⁶ for the first third of the time. -3 Pa gradually decreased to 5 × 10 -4 Pa can form an oxygen vacancy concentration from interface P1 to surface P2 (e.g., at a distance of 50 nm from the interface) that increases from 1 × 10⁻⁶. 18 ~5×10 18 cm -3 Gradually reduce to 1×10 17 ~5×10 17 cm -3 The gradient structure 21. The main body 20 is located on the side of the gradient structure 21 away from the quantum tunneling layer 3, corresponding to a higher oxygen partial pressure and a lower oxygen vacancy concentration, thereby forming a complete second semiconductor layer 2.
[0059] Furthermore, its implementation is not limited to a single sputtering process; other film formation methods such as chemical vapor deposition and molecular beam epitaxy can also be used, and similar gradient doping distributions can be achieved by adjusting parameters such as oxygen source flow rate or growth temperature. Various specific implementation structures that utilize the above principles to achieve this function fall within the scope of protection of this application.
[0060] S2: See also Figure 4B A quantum tunneling layer 3 is formed on the second semiconductor layer 2. The direction of the built-in electric field is from the second semiconductor layer 2 to the quantum tunneling layer 3.
[0061] For example, the quantum tunneling layer 3 (h-BN) can be grown using a low-temperature chemical vapor deposition (CVD) method, with a thickness of about 3 nm and a growth temperature of about 850 °C.
[0062] S3: See also Figure 4C A first semiconductor layer 1 is formed on the quantum tunneling layer 3.
[0063] For example, the first semiconductor layer 1 (i.e., the NiO layer) can be prepared by radio frequency magnetron sputtering deposition process, with a thickness of about 100 nm, a sputtering power of 150 W, and an Ar / O2 flow ratio of about 10:1.
[0064] S4: See also Figure 4D A first electrode layer 4 is formed on the side of the first semiconductor layer 1 away from the quantum tunneling layer 3, and a second electrode layer 5 is formed on the side of the second semiconductor layer 2 away from the quantum tunneling layer 3.
[0065] For example, the first electrode layer 4 can be a transparent electrode layer, particularly a transparent electrode material that can be penetrated by ultraviolet light, such as ITO material with a thickness of 80 nm and a transmittance of not less than 85% at a wavelength of 250 nm. In other examples, the first electrode layer 4 can also be made of transparent electrode materials such as indium zinc oxide (IZO), indium zinc tin oxide (IZTO), indium aluminum zinc oxide (IAZO), indium gallium zinc oxide (IGZO), indium gallium tin oxide (IGTO), aluminum zinc oxide (AZO), antimony tin oxide (ATO), gallium zinc oxide (GZO), etc.
[0066] For example, the second electrode layer 5 (i.e., the bottom electrode layer) can be prepared by an electron beam evaporation deposition process, which includes a Ti layer and an Au layer deposited sequentially, wherein the thickness of the Ti layer is about 10 nm and the thickness of the Au layer is about 100 nm.
[0067] It is understood that the characteristics and effects of each structural layer in the ultraviolet detector 100 prepared by this method can be referred to the description of each component of the ultraviolet detector 100 and the corresponding effects in any of the foregoing embodiments, and will not be repeated here.
[0068] In the ultraviolet detector 100 provided in this application embodiment, a quantum tunneling layer 3 is introduced between the first semiconductor layer 1 and the second semiconductor layer 2. The second semiconductor layer 2 has an oxygen vacancy concentration gradient structure on the side closest to the quantum tunneling layer 3, i.e., a built-in electric field is provided on this side. The direction of this built-in electric field is from the second semiconductor layer 2 to the quantum tunneling layer 3. This increases the separation and collection efficiency of photogenerated carriers, reduces dark current, and improves the device responsivity and photocurrent-to-dark-current ratio. By reasonably controlling the materials of some structural layers, the performance of the ultraviolet detector 100 can be further improved. For example, if the second semiconductor layer 2 uses In:Ga2O3, it can further achieve efficient separation and transport of photogenerated carriers and further improve the response speed and sensitivity of the ultraviolet detector 100. Furthermore, if the quantum tunneling layer 3 is made of hexagonal boron nitride, it can significantly reduce dark current.
[0069] Furthermore, the ultraviolet detector 100 provided in this application embodiment does not require an additional filter to filter the background signal, and can directly achieve high-sensitivity detection in the deep ultraviolet band of 220nm to 280nm, reducing costs while improving the practicality and reliability of the detector.
[0070] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions conceived by those skilled in the art within the scope of the technology disclosed herein should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.
Claims
1. An ultraviolet detector, characterized in that, include: A first semiconductor layer, wherein the material of the first semiconductor layer includes nickel oxide; The second semiconductor layer is stacked on top of the first semiconductor layer; The material of the second semiconductor layer includes gallium oxide; The first semiconductor layer and the second semiconductor layer have different doping types; A quantum tunneling layer is stacked between the first semiconductor layer and the second semiconductor layer; A first electrode layer is disposed on the side of the first semiconductor layer away from the quantum tunneling layer; The second electrode layer is disposed on the side of the second semiconductor layer away from the quantum tunneling layer; The second semiconductor layer has a built-in electric field on the side near the quantum tunneling layer, and the direction of the built-in electric field is from the second semiconductor layer to the quantum tunneling layer.
2. The ultraviolet detector according to claim 1, characterized in that, The strength of the built-in electric field is 10. 5 ~10 6 V / cm.
3. The ultraviolet detector according to claim 1 or 2, characterized in that, The second semiconductor layer has a gradient structure that extends from the surface of the second semiconductor layer near the quantum tunneling layer into the interior of the second semiconductor layer; from the interface between the gradient structure and the quantum tunneling layer to the surface of the gradient structure away from the quantum tunneling layer, the oxygen vacancy concentration of the gradient structure increases from 10... 18 ~5×10 18 cm -3 Gradually decrease to 10 17 ~5×10 17 cm -3 To form the built-in electric field.
4. The ultraviolet detector according to claim 3, characterized in that, The ratio of the thickness of the second semiconductor layer to the thickness of the gradient structure is 2 to 4:
1.
5. The ultraviolet detector according to any one of claims 1-4, characterized in that, The second semiconductor layer is indium doped; the concentration of the indium doping does not exceed 5 at.
6. The ultraviolet detector according to claim 5, characterized in that, The gallium oxide in the second semiconductor layer is either amorphous gallium oxide or crystalline gallium oxide.
7. The ultraviolet detector according to any one of claims 1-4, characterized in that, The quantum tunneling layer is made of hexagonal boron nitride; the thickness of the quantum tunneling layer is 2 nm to 5 nm.
8. A method for fabricating an ultraviolet detector, characterized in that, include: Forming a second semiconductor layer; The material of the second semiconductor layer includes gallium oxide; One side surface of the second semiconductor layer has a built-in electric field; A quantum tunneling layer is formed on the second semiconductor layer; the quantum tunneling layer is stacked on one side surface of the second semiconductor layer having the built-in electric field; The direction of the built-in electric field is from the second semiconductor layer to the quantum tunneling layer; A first semiconductor layer is formed on the quantum tunneling layer; the material of the first semiconductor layer includes nickel oxide; the first semiconductor layer and the second semiconductor layer have different doping types; A first electrode layer is formed on the side of the first semiconductor layer away from the quantum tunneling layer, and a second electrode layer is formed on the side of the second semiconductor layer away from the quantum tunneling layer.
9. The preparation method according to claim 8, characterized in that, The second semiconductor layer includes a gradient structure located on the side of the second semiconductor layer near the quantum tunneling layer; During the formation of the second semiconductor layer, the oxygen partial pressure is controlled to adjust the oxygen vacancy concentration from 1×10⁻⁶. 17 ~5×10 17 cm -3 Increased to 1×10 18 ~5×10 18 cm -3 To form the gradient structure.
10. The preparation method according to claim 8, characterized in that, The second semiconductor layer is indium doped; the concentration of the indium doping does not exceed 5 at.