Self-energized ultraviolet photoelectric detector based on zinc oxide homojunction and preparation method of self-energized ultraviolet photoelectric detector

Abstract

The invention discloses a self-energized ultraviolet photoelectric detector based on a zinc oxide homojunction. The self-energized ultraviolet photoelectric detector comprises a homojunction and metal electrodes, wherein the homojunction is located between two layers of conductive films and composed of an intrinsic zinc oxide film and a doped zinc oxide film, and the metal electrodes are located on the two layers of conductive films respectively. The Zn1-xMxO / ZnO homojunction has the advantages that the Zn1-xMxO / ZnO homojunction has high detection rate and quick response in the ultraviolet band by superposing the intrinsic zinc oxide and the doped zinc oxide, and the responsivity and the detection rate of the photoelectric detector are greatly improved by transient current under the pyroelectric effect compared with a traditional ultraviolet light self-energized photoelectric detector of the homojunction. Meanwhile, the preparation process is simple, the cost is low, and energy consumption is reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of photoelectric imaging detection, and in particular to a self-powered ultraviolet photoelectric detector based on zinc oxide homojunction and a preparation method thereof. Background Art

[0002] As the core component of scientific and technological information, photodetectors have important applications in modern life and production. With the rapid development of technology, people's requirements for ultraviolet detectors are increasing. However, the complex preparation process and high production cost have limited the widespread application of ultraviolet detectors. Therefore, while scientists pursue high detection and fast response, simplifying the preparation process and reducing costs have become important goals for the industrialization of detectors. In order to achieve this goal, the development of self-powered photodetectors with high detection rate, fast response, simple process, low cost and energy saving has become an important direction for the development of photoelectric detection technology. At present, ultraviolet photodetectors on the market mainly use wide bandgap semiconductor single crystal materials, such as silicon carbide (SiC), gallium nitride (GaN), tin oxide (SnO2), etc. However, single crystal materials are expensive and grow slowly, which greatly increases the production cost of ultraviolet photodetectors, and both the responsivity and detection rate need to be improved.

[0003] Therefore, there is a need for a UV photodetector with high detectivity, fast response and low cost. Summary of the invention

[0004] In view of this, the object of the present invention is to provide a self-powered ultraviolet photodetector based on zinc oxide homojunction and a preparation method thereof, which has the characteristics of high detection rate and rapid response, and the preparation process is simple and the cost is low.

[0005] The self-powered ultraviolet photoelectric detector based on zinc oxide homojunction of the present invention comprises a homojunction composed of an intrinsic zinc oxide film and a doped zinc oxide film located between two conductive films and film electrodes located on the two conductive films respectively.

[0006] Furthermore, the doped zinc oxide film is located on the intrinsic zinc oxide film, the intrinsic zinc oxide film is located on the lower conductive film, the doped zinc oxide film is located under the upper conductive film, and the doping method in the homojunction is heavy doping;

[0007] Furthermore, the chemical formula of the doped zinc oxide film is Zn 1-x M x O, wherein the element M is one of Mn, Co, Bi, Ca, Sr, and Pb, and the doping concentration x is in the range of 0.2≤x≤0.4;

[0008] Furthermore, the thickness of the doped zinc oxide film is 50nm to 500nm;

[0009] Furthermore, the doped zinc oxide film is spin-coated on the intrinsic zinc oxide film using a sol-gel method;

[0010] Furthermore, the intrinsic zinc oxide film is prepared by magnetron sputtering, and the thickness of the intrinsic zinc oxide film is 150 to 300 nm;

[0011] Furthermore, the conductive film is one of Au, Ag, Al, ITO, and FTO, and an electrode lead is provided on the conductive film;

[0012] Furthermore, the electrode lead wire is an Au, Ag or Cu wire with a diameter of 0.05 mm to 0.1 mm.

[0013] The method for preparing the self-powered ultraviolet photodetector based on zinc oxide homojunction of the present invention is characterized by comprising the following steps:

[0014] S1, the intrinsic zinc oxide thin film is prepared by magnetron sputtering: the target material of magnetron sputtering is ZnO ceramic, the substrate material is conductive glass, the sputtering power is 100-200W, the pressure is 0.5-2Pa, the argon flow rate is 30-35sccm, the oxygen flow rate is 5-10sccm, and the sputtering time is 30-60min;

[0015] S2, preparation of precursor solution of doped zinc oxide film: dissolving (CH3COO)2Zn·2H2O and (CH3COO)2M·xH2O in a methanol solution at a molar ratio of 0.1 to 0.25M, stirring for 30 to 60 minutes in a warm water bath, and aging for 24 to 48 hours to obtain a precursor solution for spin coating;

[0016] S3, spin coating the doped zinc oxide film on the intrinsic zinc oxide film: first use a low speed of 500-700 rad / min for 5-10 seconds, then use a high speed of 1500-3000 rad / min for 20-40 seconds, and then dry and anneal;

[0017] S4, preparing a conductive film by magnetron sputtering: the sputtering time is 5 to 15 minutes, the power of magnetron sputtering is 80 to 200 W, the pressure is 1 to 5 Pa, and the argon gas flow rate is 20 to 40 sccm;

[0018] Further, in step S3, the drying temperature is 180°C to 250°C, and the time is 10 to 20 minutes; a tubular furnace is used for annealing, the gas filled in the tubular furnace is argon and oxygen, the ratio of argon to oxygen is 18-20:1, the pressure is normal pressure, the annealing temperature is 450°C to 650°C, and the annealing time is 1h to 3h.

[0019] The beneficial effects of the present invention are as follows: the self-powered ultraviolet photodetector based on zinc oxide homojunction of the present invention realizes Zn 1-x M x The O / ZnO homojunction has a high detection rate and fast response in the ultraviolet band. Compared with the traditional homojunction ultraviolet light self-powered photodetector, the transient current under the pyroelectric effect greatly improves the responsivity and detection rate of the photodetector. At the same time, the preparation process is simple, low cost, and energy saving. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The present invention will be further described below in conjunction with the accompanying drawings and embodiments:

[0021] Figure 1 This is a schematic diagram of the structure of a homojunction self-powered ultraviolet photodetector based on doped zinc oxide in the present invention, in which: 1.1 is a conductive film, 1.2 is an intrinsic zinc oxide film, 1.3 is a doped zinc oxide film, 1.4 is a silver glue electrode, and 1.5 is an electrode lead;

[0022] Figure 2 In Example 1, under 325nm and 365nm laser irradiation, the ZnO / Zn 0.6 Co 0.4 Current-time response curve of O homojunction self-powered UV photodetector;

[0023] Figure 3 The current-time response curves of the zinc oxide homojunction self-powered ultraviolet photodetector doped with Mn (Example 2), Bi (Example 3), Ca (Example 4), and Sr (Example 5) in Examples 2 to 5 under 365nm laser excitation. DETAILED DESCRIPTION

[0024] The self-powered ultraviolet photodetector based on zinc oxide homojunction of the present invention in this embodiment includes a homojunction composed of an intrinsic zinc oxide film 1.2 and a doped zinc oxide film 1.3 located between two layers of conductive films 1.1, and electrode leads 1.5 led out from silver paste electrodes 1.4 located on the two layers of conductive films 1.1. The intrinsic zinc oxide film 1.2 and the doped zinc oxide film 1.3 form a homojunction located between the interlayers of the conductive films 1.1, and the two conductive films 1.1 are in an upper and lower layer relationship, one silver paste electrode 1.4 is deposited on the conductive film 1.1 corresponding to the upper end of the homojunction, and the other silver paste electrode 1.4 is deposited on the other conductive film 1.1 and has a gap with the homojunction. Zinc oxide is a non-centrosymmetric semiconductor with a hexagonal wurtzite structure, and can produce a pyroelectric photoelectric effect during light excitation. Therefore, the photodetector composed of the homogeneous structure of the intrinsic zinc oxide film 1.2 and the doped zinc oxide film 1.3 can output a transient current response when excited by ultraviolet light, and produce a pyroelectric photoelectric effect under ultraviolet light excitation, which effectively improves the responsiveness and sensitivity of the detector and greatly shortens the response time. Figure 1 It contains two layers of materials with slight differences, both of which are mainly composed of zinc oxide. 1.2 is the first layer of material, which is composed of intrinsic zinc oxide, and 1.3 is the second layer of material, which is composed of 80% ZnO and 20% MnO. There are conductive films on the upper and lower sides of both layers, and the lower electrode is deposited on the conductive glass sheet. Silver glue electrodes 1.4 lead out wires 1.5 on the conductive films 1.1 at both ends of the homojunction.

[0025] In this embodiment, the doped zinc oxide film 1.3 is located on the intrinsic zinc oxide film 1.2, the intrinsic zinc oxide film 1.2 is located on the lower conductive film 1.1, the doped zinc oxide film 1.3 is located under the upper conductive film 1.1, and the doping method in the homojunction is heavy doping; so as to obtain a larger energy band difference, thereby realizing self-powered photoelectric detection in the ultraviolet band of 325nm~365nm.

[0026] In this embodiment, the chemical formula of the doped zinc oxide film 1.3 is Zn 1-x M x O, wherein the element M is one of Mn, Co, Bi, Ca, Sr, and Pb, and the doping concentration x is in the range of 0.2≤x≤0.4; the thickness of the doped zinc oxide film 1.3 is 50nm to 500nm; so as to form a homojunction with the intrinsic zinc oxide film 1.2 and obtain a homojunction built-in electric field.

[0027] In this embodiment, the doped zinc oxide film 1.3 is spin-coated on the intrinsic zinc oxide film 1.2 by the sol-gel method; the substrate used in the spin-coating technology is usually a silicon wafer, which is placed on a suction seat with a certain rotation speed, and the solution is dripped onto the center of the substrate. Under the centrifugal force of the high-speed rotating substrate, the solution is evenly spun onto the entire substrate to form a film. Compared with commercial ultraviolet photodetectors, the preparation of doped zinc oxide by the sol-gel method has a simple device structure, small size, environmentally friendly materials, simple process, low cost, and can be mass-produced.

[0028] In this embodiment, the intrinsic zinc oxide film 1.2 is prepared by magnetron sputtering, and the thickness of the intrinsic zinc oxide film 1.2 is 150-300nm; the conductive film 1.3 is one of Au, Ag, Al, ITO, and FTO, and electrode leads are led out from the conductive film 1.3 by silver glue 1.4; the electrode leads are Au, Ag or Cu wires with a diameter of 0.05mm-0.1mm.

[0029] The method for preparing the self-powered ultraviolet photodetector based on zinc oxide homojunction of this embodiment is characterized by comprising the following steps:

[0030] S1, preparation of intrinsic zinc oxide thin film 1.2 by magnetron sputtering: the target material of magnetron sputtering is ZnO ceramic, the substrate material is conductive glass, the sputtering power is 100-200W, the pressure is 0.5-2Pa, the argon flow rate is 30-35sccm, the oxygen flow rate is 5-10sccm, and the sputtering time is 30-60min;

[0031] S2, preparation of the precursor solution of the doped zinc oxide film 1.3: dissolve (CH3COO)2Zn·2H2O and (CH3COO)2M·xH2O in a methanol solution at a molar ratio of 0.1 to 0.25 M, stir for 30 to 60 min in a warm water bath, and allow to stand for aging for 24 to 48 h to obtain a precursor solution for spin coating;

[0032] S3, spin coating the doped zinc oxide film 1.3 on the intrinsic zinc oxide film 1.2: first use a low speed of 500-700 rad / min for 5-10s, then use a high speed of 1500-3000 rad / min for 20-40s, then dry and anneal; the drying temperature is 180℃~250℃, and the time is 10-20min; use a tubular furnace for annealing, the gas filled in the tubular furnace is argon and oxygen, the ratio of argon to oxygen is 19:1, the pressure is normal pressure, the annealing temperature is 450℃~650℃, and the annealing time is 1h~3h.

[0033] S4, using magnetron sputtering to prepare thin film electrodes: the sputtering time is 5 to 15 minutes, the power of magnetron sputtering is 80 to 200 W, the pressure is 1 to 5 Pa, and the argon flow rate is 20 to 40 sccm; the process is simple, low cost, and energy saving.

[0034] Embodiment 1

[0035] A ZnO / Zn 1-x M x The preparation method of a homojunction photodetector comprises the following steps:

[0036] S1, the intrinsic zinc oxide film 1.2 is prepared by magnetron sputtering. The target material of magnetron sputtering is ZnO ceramic, the substrate material is conductive glass, the sputtering power is 150W, the pressure is 1Pa, the argon flow rate is 30sccm, the oxygen flow rate is 7sccm, the sputtering time is 45min, and the intrinsic zinc oxide thickness is 230nm;

[0037] S2, the preparation scheme of the precursor solution of the doped zinc oxide film 1.3 is as follows: (CH3COO)2Zn·2H2O and (CH3COO)2M·xH2O are weighed in a molar ratio; the weighed substances are dissolved in a methanol solution at a concentration of 0.15M (total substance: solvent), stirred in a warm water bath for 45 minutes, and aged for 35 hours to obtain a precursor solution for spin coating;

[0038] S3, spin coating the doped zinc oxide film 1.3 on the intrinsic zinc oxide film 1.2: low speed of 600 rad / min, time of 7 s, high speed of 2300 rad / min, time of 30 s, baking temperature of 220°C, baking time of 15 min, baking environment of air environment, annealing temperature of 550°C, annealing time of 2 h, the gas filled in the tube furnace is argon and oxygen, the ratio of argon to oxygen is 19:1, and the pressure is normal pressure;

[0039] A zinc oxide film of 100 nm was deposited on an ITO glass substrate to obtain a zinc oxide film; on this basis, a (CH3COO)2Zn methanol solution with a concentration of 0.25 M and a doping concentration of 40% was spin-coated three times, and then annealed after drying to obtain a Co-doped zinc oxide film. The chemical formula of the Co-doped zinc oxide film is Zn 0.6 Co 0.4 O, the thickness of the doped zinc oxide film 1.3 is 150nm.

[0040] S4, prepare the electrode by magnetron sputtering: the sputtering time is 10min, the electrode thickness is 150nm, the magnetron sputtering power is 150W, the pressure is 3Pa, and the argon flow rate is 30sccm; deposit an ITO electrode on the top of the Co-doped zinc oxide film 1.3, and the electrode thickness is 150nm.

[0041] S5, lead out the electrode lead on the upper side of the silver glue electrode 1.4, the lead diameter is 0.05mm~0.1mm, and the material is Cu wire.

[0042] 325nm and 365nm lasers were used as excitation light sources, with a spot area of ​​0.2cm 2 , the spot energy density is 10μW / cm 2 , using low noise current preamplifier and data acquisition card to measure ZnO / Zn 0.6 Co 0.4 The current generated by the O homojunction is recorded. Figure 2 shown.

[0043] Embodiments 2 to 5

[0044] The preparation methods of Examples 2 to 5 are the same as those of Example 1, except that the doping elements are changed, that is, the doping elements can be Mn (Example 2), Bi (Example 3), Ca (Example 4), Sr (Example 5). Under 365nm laser excitation, the current signal is as follows Figure 3 shown.

[0045] Embodiments 6 to 8

[0046] The preparation methods of Examples 6 to 8 are the same as those of Example 1, except that the thickness of the doped film is changed. 0.6 Co 0.4 The thickness of the O film is 100 nm (Example 6), 200 nm (Example 7), and 300 nm (Example 8).

[0047] Embodiments 9-10

[0048] The preparation methods of Examples 9 to 10 are the same as those of Example 1, except that the concentration of the doping element is changed. 1- x Co x The contents of x in the O film are 0.2 (Example 9) and 0.3 (Example 10).

[0049] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the purpose and scope of the technical solution of the present invention, which should be included in the scope of the claims of the present invention.

Claims

1. A self-powered ultraviolet photodetector based on zinc oxide homojunction, characterized in that: The invention comprises a homojunction formed by an intrinsic zinc oxide film and a doped zinc oxide film located between two conductive films, and metal electrodes located on the two conductive films respectively.

2. The self-powered ultraviolet photodetector based on zinc oxide homojunction according to claim 1, characterized in that: The doped zinc oxide film is located on the intrinsic zinc oxide film, the intrinsic zinc oxide film is located on the lower conductive film, the doped zinc oxide film is located under the upper conductive film, and the doping method in the homojunction is heavy doping.

3. The self-powered ultraviolet photodetector based on zinc oxide homojunction according to claim 1, characterized in that: The chemical formula of the doped zinc oxide film is Zn 1-x M x O, wherein the element M is one of Mn, Co, Bi, Ca, Sr, and Pb, and the doping concentration x is in the range of 0.2≤x≤0.

4.

4. The self-powered ultraviolet photodetector based on zinc oxide homojunction according to claim 3, characterized in that: The thickness of the doped zinc oxide film is 50nm-500nm.

5. The self-powered ultraviolet photodetector based on zinc oxide homojunction according to claim 4, characterized in that: The doped zinc oxide film is spin-coated on the intrinsic zinc oxide film by using a sol-gel method.

6. The self-powered ultraviolet photodetector based on zinc oxide homojunction according to claim 1, characterized in that: The intrinsic zinc oxide film is prepared by magnetron sputtering, and the thickness of the intrinsic zinc oxide film is 150-300 nm.

7. The self-powered ultraviolet photodetector based on zinc oxide homojunction according to claim 1, characterized in that: The conductive film is one of Au, Ag, Al, ITO and FTO, and electrode leads are arranged on the conductive film.

8. The self-powered ultraviolet photodetector based on zinc oxide homojunction according to claim 7, characterized in that: The electrode lead wire is Au, Ag or Cu wire with a diameter of 0.05 mm to 0.1 mm.

9. The method for preparing a self-powered ultraviolet photodetector based on zinc oxide homojunction according to claim 1, characterized in that: The following steps are involved: S1, the intrinsic zinc oxide thin film is prepared by magnetron sputtering: the target material of magnetron sputtering is ZnO ceramic, the substrate material is conductive glass, the sputtering power is 100-200W, the pressure is 0.5-2Pa, the argon flow rate is 30-35sccm, the oxygen flow rate is 5-10sccm, and the sputtering time is 30-60min; S2, preparation of precursor solution of doped zinc oxide film: dissolving (CH3COO)2Zn·2H2O and (CH3COO)2M·xH2O in a methanol solution at a molar ratio of 0.1 to 0.25M, stirring for 30 to 60 minutes in a warm water bath, and aging for 24 to 48 hours to obtain a precursor solution for spin coating; S3, spin coating the doped zinc oxide film on the intrinsic zinc oxide film: first use a low speed of 500-700 rad / min for 5-10 seconds, then use a high speed of 1500-3000 rad / min for 20-40 seconds, and then dry and anneal; S4, preparing a conductive film by magnetron sputtering: the sputtering time is 5 to 15 minutes, the power of magnetron sputtering is 80 to 200 W, the pressure is 1 to 5 Pa, and the argon gas flow rate is 20 to 40 sccm.

10. The method for preparing a self-powered ultraviolet photodetector based on zinc oxide homojunction according to claim 9, characterized in that: In step S3, the drying temperature is 180°C to 250°C, and the time is 10 to 20 minutes; a tubular furnace is used for annealing, the gas filled in the tubular furnace is argon and oxygen, the ratio of argon to oxygen is 18-20:1, the pressure is normal pressure, the annealing temperature is 450°C to 650°C, and the annealing time is 1h to 3h.

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