JP4164563B2 - Oxide semiconductor PN junction device and manufacturing method thereof - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a PN junction device, and more particularly to a PN junction device composed of an oxide semiconductor compound thin film that can be used for an ultraviolet light sensor sensitive to ultraviolet rays of a specific wavelength, a solar cell, and the like, and a manufacturing method thereof.
[0002]
[Prior art]
PN junctions using single element semiconductors such as Si and Ge and compound semiconductors such as GaAs, InP, and GaN have been widely put into practical use as solid-state electronic devices and solid-state optoelectronic devices. As electronic devices, they are used in bipolar transistors, rectifier diode devices, and the like. On the other hand, as an optoelectronic device, it is used for a semiconductor laser, a light emitting diode, a light detection element, a solar cell, and the like. In these devices, a homo PN junction composed of the same kind of compound is often used. However, in semiconductor lasers, light emitting diodes, etc., a hetero PN junction composed of a different compound is used.
[0003]
Regarding optoelectronic devices, devices that function in a wide wavelength range are required, but it is impossible in principle to meet the requirements with one material, and different materials are used depending on the wavelength. However, a device that functions sufficiently has not been developed particularly in the ultraviolet wavelength region. In addition, many of these PN junction-forming materials, particularly compound semiconductor materials, are chemically and thermally unstable, and are also environmentally harmful or resource depleted. Many. Some of the problems of such a PN junction device using a semiconductor material can be solved by using an oxide semiconductor material.
[0004]
In 1997, CuAlO₂Since the development of the first oxide having p-type conductivity using Non-Patent Document 1 (Non-Patent Document 1), the development of a PN junction using an oxide has been conducted. p-SrCu₂O₂A hetero PN junction was developed to realize an ultraviolet light emitting diode (Non-patent Document 2, Patent Document 1). In addition, a light-emitting diode using an n-ZnO / p-NiO hetero PN junction has been developed and applied for a patent (Ota et al., Japanese Patent Application No. 2002-70165).₂Homozygous using this is developed (Non-patent Document 3).
[0005]
[Patent Document 1]
Japanese Patent Laid-Open No. 2001-210864 (WO0156088)
[0006]
[Non-Patent Document 1]
Kawade, et al., Nature, 389, 939, 1997
[Non-Patent Document 2]
Ota et al. Appl. Phys. Lett. 76, 2740 (2000)
[Non-Patent Document 3]
Yanagi et al. Solid State Communication 121, 15 (2002)
[0007]
Although PN junction devices using oxide semiconductors that have been developed so far function as rectifier diodes, light-emitting elements, and solar cells, they currently have luminous efficiency compared to PN junction devices that use compound semiconductor materials. Therefore, it is necessary to improve the device characteristics. However, based on the material properties of oxide semiconductors compared to compound semiconductor compounds, PN junction devices using oxide semiconductors are inherently stable, chemically stable, excellent in high temperature resistance, and have low environmental impact. It has many advantages. Furthermore, when viewed only in optoelectronic devices that function in the short wavelength light region, a PN junction device using an oxide semiconductor can be regarded as having great potential to surpass the characteristics of a compound semiconductor PN junction device.
[0008]
[Problems to be solved by the invention]
Since it was pointed out that ultraviolet rays with a specific wavelength, particularly UV-B called UV-B, with a wavelength of 320 nm to 280 nm, cause skin cancer and cataracts, ultraviolet light sensitive to that wavelength. The detector began to be put into practical use. Currently, GaN is used as a device material for detecting ultraviolet light. GaN is visible and ultravioletwavelengthIn order to have photosensitivity in the region, in the device, it is necessary to remove unnecessary light using an optical filter and to allow only ultraviolet light having a specific wavelength to enter the GaN detector.
[0009]
[Means for Solving the Problems]
The present invention relates to a p-type conductive oxide semiconductor compound and an n-typeElectricalConductivityIndicateHas ultraviolet light sensitivityOxide semiconductorCompoundWhenA PN junction device comprising the above and a manufacturing method thereof are provided.
[0010]
That is, the present invention is as follows.
(1) A PN junction device composed of an oxide semiconductor compound thin film and having a photodetection function in the ultraviolet wavelength region, and having n-type conductivity epitaxially grown on an ITO single crystal film used as an n-type transparent electrode Zn with UV sensitivity_xMg_1-xO (provided that 0.7 <x ≦ 1) single crystal thin film, the Zn_xMg_1-xA NiO single crystal thin film containing 10 to 30 at% of Li ions exhibiting p-type conductivity, deposited as a polycrystalline or amorphous film on an O single crystal thin film and epitaxially grown by diffusion treatment by annealing, was formed on the NiO single crystal thin film.p-typeIt consists of a metal film or ITO thin film used as an electrode, and the Zn_xMg_1-xA PN junction device, wherein an O single crystal thin film and a NiO single crystal thin film containing Li ions form a heteroepitaxial interface.
[0011]
(2) A PN junction device composed of an oxide semiconductor compound thin film and having a photodetection function in the ultraviolet wavelength region, and having n-type conductivity epitaxially grown on an ITO single crystal film used as an n-type transparent electrode Zn with UV sensitivity_xMg_1-xO (provided that 0.7 <x ≦ 1) single crystal thin film, the Zn_xMg_1-xZnRh showing p-type electrical conductivity deposited as a polycrystalline or amorphous film on an O single crystal thin film and epitaxially grown by diffusion treatment by annealing₂O₄Single crystal thin film, ZnRh₂O₄Deposited on single crystal thin filmp-typeIt consists of a metal film or ITO thin film used as an electrode, and the Zn_xMg_1-xO single crystal thin film and ZnRh₂O₄A PN junction device, wherein the single crystal film forms a heteroepitaxial interface.
[0012]
(3) A PN junction device composed of an oxide semiconductor compound thin film and having a photodetection function in the ultraviolet wavelength region, and exhibits n-type conductivity deposited on an ITO film used as an n-type transparent electrode. Amorphous InGaO with ultraviolet light sensitivity₃(ZnO)_m(M is an integer of 1 to less than 50) Thin film, InGaO₃(ZnO)_mAmorphous NiO thin film or amorphous ZnRh exhibiting p-type conductivity deposited on top₂O₄Thin film, amorphous NiO thin film or amorphous ZnRh₂O₄Deposited on a thin filmp-typeIt consists of a metal film or ITO thin film used as an electrode, and the amorphous InGaO₃(ZnO)_m(M is an integer of 1 to less than 50) A thin film and the amorphous NiO thin film or amorphous ZnRh₂O₄A PN junction device, wherein a thin film forms a heterointerface.
[0013]
(4) Consists of oxide semiconductor compound thin filmsHas light detection function in the ultraviolet wavelength regionA method of manufacturing a PN junction device, comprising Zn on an ITO single crystal film_xMg_1-xO single crystal thin film is epitaxially grown, and the Zn_xMg_1-xO (provided that 0.7 <x ≤ 1) Li ions on the single crystal thin film10-30at%Deposit polycrystalline or amorphous NiO thin film containing 600 ° C~ 1500 ° CAnnealing at a temperature ofDiffusion process byAnd epitaxially growingThe polycrystalline or amorphous NiO thin film is a NiO single crystal thin filmZn_xMg_1-xO single crystal thin film and NiOSingle crystalFormation of heteroepitaxial interface with thin filmA metal film or ITO thin film is formed on the NiO single crystal thin film.(1) The manufacturing method of the PN junction device according to (1) above.
[0014]
(5) Consists of oxide semiconductor compound thin filmHas light detection function in the ultraviolet wavelength regionA method of manufacturing a PN junction device, comprising Zn on an ITO single crystal film_xMg_1-xO (provided that 0.7 <x ≦ 1) single crystal thin film is epitaxially grown, and the Zn_xMg_1-xPolycrystalline or amorphous ZnRh on O single crystal thin film₂O₄Deposit the film at 600 ° C~ 1500 ° CAnnealing at a temperature ofDiffusion process byAnd epitaxially growingThe polycrystalline or amorphous ZnRh ₂ O ₄ The film is made of ZnRh ₂ O ₄ With a single crystal thin film,Zn_xMg_1-xO single crystal thin film and ZnRh₂O₄ Single crystal thinForms a heteroepitaxial interface with the filmAnd the ZnRh ₂ O ₄ Form a metal film or ITO thin film on a single crystal thin film(2) The method for producing a PN junction device according to (2) above.
[0015]
(6) Consists of oxide semiconductor compound thin filmHas light detection function in the ultraviolet wavelength regionA method for manufacturing a PN junction device, comprising amorphous InGaO on an ITO film₃(ZnO)_m(M is an integer of 1 or more and less than 50) A thin film is deposited, and the InGaO₃(ZnO)_mAmorphous NiO thin film on the thin film oramorphousZnRh₂O₄Thin filmSubstrate temperature 100 ° C or lessDeposit, theamorphousInGaO₃(ZnO) thin film and theamorphousNiO thin film oramorphousZnRh₂O₄Form hetero interface with thin filmThe amorphous NiO thin film or amorphous ZnRh ₂ O ₄ Form a metal film or ITO thin film on the thin film(3) The method for producing a PN junction device according to (3) above.
(7) A photodetector having selective sensitivity in the ultraviolet wavelength region using the PN junction device according to any one of (1) to (3) above.
[0016]
A GaN UV detector that has already been put to practical use uses a so-called Schottky junction in which a Schottky metal is deposited on GaN. However, metal and Zn_xMg_1-xAt the bonding interface of O (0.7 <x ≦ 1), Zn_xMg_1-xBy forming an interface energy level such as oxygen defect of O (0.7 <x ≦ 1), the metal electrode becomes ohmic contact, and the work function of Schottky metal such as Au or Pt. And Zn_xMg_1-xSince the difference from the Fermi energy of O (0.7 <x ≦ 1) is small (˜0.3 eV), Zn_xMg_1-xWith O (0.7 <x ≦ 1), it is difficult to form a metal Schottky junction. Therefore, Zn_xMg_1-xIn O (0.7 <x ≦ 1), it is necessary to produce a PN junction having a light detection function instead of a metal Schottky junction.
[0017]
In the photodetector having sensitivity in the ultraviolet wavelength region of the present invention, Zn_xMg_1-xUltraviolet light is absorbed by the O (0.7 <x ≦ 1) layer, and photoinduced carriers (electron hole pairs) are formed at the PN junction. The generated electron hole pair is separated by an internal electric field generated at the PN junction, and nTypeElectrode and pTypeA photovoltaic force is generated between the electrodes.
[0018]
Since the photovoltaic force is proportional to the intensity of the irradiated ultraviolet light, the PN junction device can be used as an ultraviolet light detector. Further, since the photosensitivity has a sharp selectivity with respect to the ultraviolet wavelength, it is possible to detect only ultraviolet rays having a specific wavelength without using an element excluding extra light such as a color filter. The wavelength of absorbed ultraviolet light, that is, the photosensitivity spectrum,Zn _x Mg _1-x O'sComposition parameter x(0.7 <x ≦ 1)Can be controlled by the value of. ZnO and MgO have different crystal structures, so Zn_xMg_1-xIf the value of x in O is less than 0.7, that is, the amount of Mg relative to Zn is 30atomIf it exceeds 50%, a uniform and good quality mixed crystal cannot be obtained.
[0019]
In addition, the PN junction composed of an epitaxial thin film has higher ultraviolet detection sensitivity at each wavelength than the PN junction composed of an amorphous thin film. However, since the current generated by ultraviolet irradiation is proportional to the area of the light receiving surface, a PN junction made of an amorphous film that can be manufactured at low cost is suitable when the light receiving surface may be large.
[0020]
DETAILED DESCRIPTION OF THE INVENTION
First, an embodiment in the case of forming a PN junction composed of an epitaxial thin film will be described in detail below.
(substrate)
The substrate for forming an epitaxial PN junction by the oxide semiconductor thin film used in the PN junction device of the present invention has heat resistance and is a transparent oxide single crystal substrate, for example, YSZ (yttria stabilized zirconia), sapphire, MgO, ZnO or the like is used. Of these, YSZ is most preferable because it has a lattice constant close to that of ITO and does not chemically react with the compound at a temperature of 1400 ° C. or lower. In addition, the substrate needs to be transparent to the ultraviolet rays to be detected. The surface mean square roughness Rms of these substrates is preferably 1.0 nm or less. Rms can be calculated by scanning a 1 μm square with an atomic force microscope, for example.
[0021]
An ultra-flat surface can be obtained by heating an oxide single crystal substrate such as YSZ to 1000 ° C. or higher in the air or in vacuum. A structure reflecting the crystal structure appears on the surface of the ultra flattened oxide single crystal substrate. That is, it is a structure composed of a terrace having a width of about several hundreds of nanometers and a step having a height of about a sub-nanometer (nm), and is generally called an atomically flattened structure.
[0022]
The terrace portion is composed of atoms arranged in a plane, and is a completely flattened surface if the presence of some defects is ignored. Due to the presence of steps, the entire substrate is not a completely planarized surface. If this structure is expressed in terms of roughness Rms by the mean square roughness measurement method, Rms is 1.0 nm or less. Rms is a value calculated by, for example, scanning an area of 1 μm square with an atomic force microscope, for example.
[0023]
(Epitaxial growth of ITO single crystal thin film)
An ITO single crystal thin film having an atomic flat surface is epitaxially grown on the obtained heat-resistant transparent oxide single crystal substrate having an atomic flat surface by MBE, pulsed laser deposition (PLD), or the like. ITOSingle crystalThin film is n-typeTransparentUsed as an electrode.
[0024]
(Zn_xMg_1-xEpitaxial growth of O compound thin film)
Next, the ITOSingle crystalZn on the thin film_xMg_1-xAn O (provided that 0.7 <x ≦ 1) compound thin film is epitaxially grown. For the growth, an MBE method, a pulsed laser deposition method (PLD method), a sputtering method, a CVD method, or the like can be used. In this case, the target is Zn_yMg_1-yO (0.8 <y ≦ 1) is used. Zn by PLD method_xMg_1-xWhen producing O (however, 0.7 <x ≦ 1), the target material preferably has a slightly reduced Mg concentration. Zn at high temperature_xMg_1-xO (however, 0.7 <x ≦ 1)Single crystalWhen manufacturing a thin film, the vapor pressure of ZnO and MgO is ZnO> MgO.Single crystalThis is because the composition ratio of ZnO / MgO deposited on the thin film is smaller than the composition ratio of the target.
[0025]
(NiO thin film or ZnRh₂O₄Thin film deposition)
Zn_1-xMg_xOn the O epitaxial film, a NiO thin film or ZnRh₂O₄Deposit a thin film. For the thin film deposition, an MBE method, a pulse laser deposition method (PLD method), a sputtering method, a CVD method, or the like can be used. When depositing a NiO thin film, a Li-doped NiO sintered body (Li concentration 0 to 30 atomic%) is used as a target. ZnRh₂O₄When depositing a thin film, the target is ZnRh.₂O₄A sintered body is used. The obtained thin film does not need to be a single crystal film, and may be a polycrystalline film or an amorphous film. The most important parameter for film deposition is the substrate temperature. The substrate temperature must be 100 ° C. or lower. When the temperature exceeds 100 ° C., the p-type oxide semiconductor NiO thin film or ZnRh₂O₄The composition shift and grain growth of the thin film are likely to occur, and flattening is hindered.
[0026]
(Annealing)
Finally, high melting point compounds such as YSZ or Al so that the entire thin film can be covered₂O₃And diffusion treatment by annealing at high temperature and atmospheric pressure. The diffusion treatment temperature by annealing is preferably 600 ° C to 1500 ° C. Below 600 ° C., atoms cannot sufficiently migrate on the surface of the thin film, and the p-type oxide semiconductor NiO or ZnRh₂O₄A single crystal thin film cannot be obtained. Further, a high temperature exceeding 1500 ° C. is not preferable because a chemical reaction occurs between most substrate materials and thin films. The reason for covering with the high melting point compound is to avoid contamination of the thin film surface. AnnealingDiffusion processing byByThe NiO thin film or ZnRh ₂ O ₄ The thin film becomes a single crystal thin filmZn_xMg_1-xO single crystal thin film and NiOSingle crystalThin film or ZnRh₂O₄ Single crystalA heteroepitaxial interface with the thin film is formed.
[0027]
Zn_xMg_1-xO (however, 0.7 <x ≦ 1)Single crystalThe thin film exhibits n-type conductivity without any intentional addition of impurities. This is due to the non-stoichiometric nature of ZnO, and the deviation from the electrical neutral condition caused by oxygen deficiency is maintained by generating 2 electrons per oxygen deficiency. This is to try. In addition, intentional impurity doping is also effective, and low-resistance n-type Zn is obtained by substitution doping (about several at%) of Al, Ga, and In, which are trivalent ions._xMg_1-xO (however, 0.7 <x ≦ 1)Single crystal thin filmCan be produced. Zn_xMg_1-xO (however, 0.7 <x ≦ 1)Single crystal thin filmThe relationship between the band gap and x is proportional, for example, 3.3 eV when x = 1 and 3.8 eV when x = 0.8.
[0028]
The p-type conductivity of the NiO single crystal thin film can be controlled by changing the concentration of Li ions acting as an acceptor. For example, when no Li ion is added, 10^-4Although the conductivity is S / cm, the conductivity becomes 0.3 S / cm by doping Li ions at 10 at%. Doping can be controlled by changing the Li concentration in the sintered compact target. The Li concentration as an acceptor must be 30 at% or less. Compound LiNiO that is not NiO when doping with Li ions exceeding 30at%₂This is because it will change.
[0029]
When annealing at 600 ° C. or higher, NiOSingle crystalLi ions added to the thin film are likely to evaporate. In order to prevent such Li ion evaporation, NiOSingle crystalThe thin film surface is preferably capped with a YSZ single crystal substrate or the like.
ZnRh₂O₄ Single crystal thin filmShows p-type conductivity without any intentional addition of impurities.
[0030]
Finally, the metal film or ITO thin film used as the p-type electrode is replaced with NiO.Single crystalThin film or ZnRh₂O₄ Single crystalA film is formed on the thin film. A photodetection diode is produced from the PN junction multilayer film thus obtained by using ordinary light exposure and etching techniques. The n-type electrode uses an ITO thin film produced on a substrate.
[0031]
Next, an embodiment in the case of forming a PN junction composed of an amorphous thin film will be described in detail below.
(substrate)
For the formation of a PN junction formed from an amorphous thin film, the substrate does not need to have heat resistance, and ultravioletwavelengthTransparent SiO₂The glass substrate which has as a main component can be used. The flatness may be about the same as that of a glass substrate used for an amorphous silicon field effect transistor.
[0032]
(Deposition of ITO thin film)
An ITO thin film is deposited on such a glass substrate. The ITO thin film is preferably an amorphous film from the viewpoint of surface flatness, but is not limited to an amorphous film, and may be a polycrystalline film.
[0033]
(InGaO₃(ZnO)_mThin film deposition)
Zn_xMg_1-xAn O (provided that 0.7 <x ≦ 1) thin film is difficult to obtain an amorphous film, and is usually a polycrystalline film. When making the n-type conductive layer an amorphous thin film,_xMg_1-xInstead of O (but 0.7 <x ≦ 1) thin film, InGaO₃(ZnO)_m(M is an integer from 1 to less than 50)amorphousA thin film may be deposited. InGaO₃(ZnO)_m(M is an integer of 1 or more and less than 50) If the thin film is formed at room temperature, an amorphous state can be easily obtained.
[0034]
(Amorphous NiO thin film or amorphous ZnRh₂O₄Thin film deposition)
Next, InGaO₃(ZnO)_mAmorphous NiO thin film or amorphous ZnRh on the thin film₂O₄Deposit a thin film as beforeamorphousInGaO₃(ZnO) thin film and theamorphousNiO thin film oramorphousZnRh₂O₄A hetero interface with the thin film is formed. The most important parameter for film deposition is the substrate temperature. An amorphous film cannot be obtained unless the substrate temperature is 100 ° C. or lower. When the temperature exceeds 100 ° C., the p-type oxide semiconductor NiO or ZnRh₂O₄Deviations in composition and grain growth of the thin film are likely to occur, resulting in polycrystallization and hinder flattening. When forming a PN junction composed of an amorphous thin filmOf deposited filmAnnealing is not necessary.
[0035]
Finally, a metal film or amorphous ITO thin film used as a p-type electrode is replaced with an amorphous NiO thin film oramorphousZnRh₂O₄A film is formed on the thin film. A photodetection diode is produced from the PN junction multilayer film thus obtained by using ordinary light exposure and etching techniques. The n-type electrode uses an ITO thin film produced on a substrate.
[0036]
【Example】
Hereinafter, the present invention will be described in detail with reference to examples.
Example 1
Fabrication of NiO UV photodetector
On the YSZ (111) single crystal substrate by PLD methodUsed as n-type transparent electrodeITOSingle crystalA thin film was epitaxially grown. Produced ITOSingle crystalThe thin film was colorless and transparent throughout the visible light region, and the conductivity was 10,000 S / cm.
Zn was produced on the ITO single crystal film thus produced at a substrate temperature of 700 ° C._0.8Mg_0.2OSingle crystalThe thin film was laminated by the PLD method. Zn_0.8Mg_0.2OSingle crystalThe thin film was epitaxially grown, and a structure in which hexagonal spiral grains were densely arranged on the surface was observed.
[0037]
Next, the substrate temperature was set to room temperature, and a NiO: Li thin film was deposited by irradiating a NiO sintered body target containing 10 at% Li with a laser beam by a PLD method. The film thickness was 300 nm. Next, the produced NiO: Li thin film is taken out from the vacuum vessel, and the thin film surface is covered with a YSZ single crystal plate on the thin film to prevent evaporation of the Li component during annealing, and in the atmosphere at 1300 ° C. for 30 minutes. After annealing, cool to room temperatureNiO: Li thin film is a single crystal thin filmIt was. When the XRD measurement of the produced two-layer thin film was performed, NiO: LiSingle crystalThin film is Zn_0.8Mg_0.2OSingle crystalIt was found that heteroepitaxial growth was performed on the thin film.
[0038]
Further, a p-type electrode is formed on the NiO: Li single crystal thin film,The produced laminated film was processed into a mesa device by photolithography and a dry etching process. FIG. 1 shows a photoelectric conversion spectrum. Spectral xenon lamp light was used as the excitation light. A photoelectric conversion peak was observed near 3.8 eV. This is Zn_0.8Mg_0.2It corresponds to the band gap of O and NiO. That is, Zn_0.8Mg_0.2It has been shown that an electromotive force is efficiently generated by absorbing light in the band gap of O and NiO, and functions as an ultraviolet light detector. In particular, since it shows a steep sensitivity in the UV-B region, which is harmful ultraviolet light, it can be applied as a harmful ultraviolet light sensor.
[0039]
Example 2
Amorphous p-ZnRh₂O₄Thin film fabrication method
First, ZnRh deposited on a silica glass substrate₂O₄In order to confirm that the thin film is in an amorphous state, ZnRh is formed by RF sputtering.₂O₄ZnRh on a silica glass substrate using a polycrystal as a target₂O₄A thin film was prepared. The sputtering conditions are: high frequency output = 180 W, gas atmosphere Ar / O₂= 9: 1 and the substrate temperature is room temperature. The growth rate was 10 nm / min.
[0040]
The produced thin film sample was subjected to X-ray diffraction measurement, cross-sectional TEM observation, light transmittance measurement, electrical conductivity measurement by a direct current four-terminal method, and thermoelectromotive force measurement. The X-ray diffraction pattern (FIG. 2) of the thin film sample was composed only of halo-like broad peaks, and the sample was in an amorphous state as far as it was evaluated from X-ray diffraction. The optical gap obtained from the light absorption spectrum (FIG. 3) was ˜2 eV. Seebeck coefficient is + 80μVK^-1And the carrier was a hole. Electrical conductivity at room temperature is ~ 1Scm^-1The electrical conduction was an Arrhenius type with an activation energy of ˜30 meV. From the TEM observation (FIG. 4), it was revealed that the sample was composed of fine crystals of 2 to 3 nm. That is, it can be said that it is an X-ray amorphous thin film.
[0041]
n-ZnO / p-ZnRh₂O₄ Made of single crystal thin film PN junctionFabrication of ultraviolet light detector
ITO on YSZ (111) single crystal substrate by PLD methodSingle crystalA thin film was epitaxially grown. Produced ITOSingle crystalThe thin film was colorless and transparent throughout the visible light region, and the conductivity was 10,000 S / cm. Next, ZnO at a substrate temperature of 700 ° C.Single crystalThe thin film was laminated by the PLD method. ZnOSingle crystalThe thin film was epitaxially grown, and a structure in which hexagonal spiral grains were densely arranged on the surface was observed. Furthermore, ZnOSingle crystal thin filmZnRh on₂O₄A thin film was deposited at room temperature by the PLD method. ZnO at room temperatureSingle crystal thin filmZnRh deposited on₂O₄Thin filmA small partAs a result of XRD measurement, it is ZnRh₂O₄A very weak diffraction peak is seen from the thin filmAmorphous stateIt was.
[0042]
The laminated film thus fabricated is annealed in the atmosphere at 950 ° C. for 30 minutes, and cooled to room temperature.ZnRh ₂ O ₄ The thin film is a single crystal thin filmIt was. FIG. 5 shows an XRD pattern of the laminated thin film measured after annealing. ZnRh₂O₄ Single crystal thin film, ZnOSingle crystal thin film, ITOSingle crystal thin filmIs strongly oriented on the YSZ (111) substrate, and its orientation relationship is ZnRh.₂O₄It was (111) [110] || ZnO (0001) [11-20] || ITO (111) [110] || YSZ (111) [110]. ZnRh₂O₄ Single crystal thin film/ ZnOSingle crystal thin filmWhen the bonding interface was observed with a high-resolution transmission electron microscope (FIG. 6), ZnRh₂O₄ Single crystal thin filmAnd ZnOSingle crystal thin filmWas confirmed to be neatly heteroepitaxially grown. ZnRh₂O₄ Single crystal thin film/ ZnOSingle crystal thin filmThe vicinity of the bonding interface was bonded at the atomic level, and no precipitation of other crystals was observed.
[0043]
Further, as shown in the interpolation diagram of FIG. ₂ O ₄ Au is deposited as a p-type electrode on a single crystal thin film,The produced laminated film was processed into a mesa device as shown in the inset of FIG. 7 by photolithography and a dry etching process. FIG. 7 shows the current-voltage characteristics of the fabricated mesa device. The rectifying characteristic found in a typical PN junction diode was obtained, and the forward bias rise was about 2V. This value is ZnRh₂O₄It agrees well with the band gap (about 2.1 eV).
[0044]
FIG. 8 shows a photoelectric conversion spectrum. Spectral xenon lamp light was used as the excitation light. A photoelectric conversion peak was observed near 3.2 eV. This corresponds to the band gap of ZnO. In other words, it was shown that ZnO band gap light was absorbed to efficiently generate an electromotive force and function as an ultraviolet light detector.
[0045]
Example 3
n-InGaZnO₄/ P-ZnRh₂O₄Fabrication of amorphous PN junction
Used as n-type electrodeCommercially available ITO polycrystalline thin film (SiO₂N-type oxide semiconductor InGaZnO formed at room temperature on an ITO thin film formed on a glass substrate by sputtering)₄Was formed by the PLD method. The deposited thin film was in an amorphous state.
[0046]
Next, the amorphous p-ZnRh of Example 2 was used.₂O₄With thin film production methodamorphousZnRh₂O₄Thin films were laminated.Furthermore, as shown in FIG. 9, amorphous ZnRh ₂ O ₄ Au is deposited on the thin film as a p-type electrode,The produced laminated film was processed into a mesa device as shown in FIG. 9 by photolithography and dry etching process. FIG. 10 shows the current-voltage characteristics of the diode measured at room temperature. A steep rectification characteristic was obtained.
[Brief description of the drawings]
FIG. 1 shows epitaxial p-NiO: Li / n-Zn in Example 1. FIG._0.8Mg_0.2OIt is a photoelectric conversion spectrum of a junction diode.
2 is an X-ray amorphous p-ZnRh in Example 2. FIG.₂O₄It is an XRD pattern of a thin film.
3 is an X-ray amorphous p-ZnRh in Example 2. FIG.₂O₄It is a light absorption spectrum of a thin film.
4 is an X-ray amorphous p-ZnRh in Example 2. FIG.₂O₄It is a drawing substitute photograph which shows the TEM image of a thin film.
FIG. 5 shows epitaxially grown p-ZnRh in Example 2.₂O₄It is a XRD pattern of / n-ZnO / ITO thin film.
6 shows p-ZnRh in Example 2. FIG.₂O₄5 is a drawing-substituting photograph showing a high-resolution electron microscope image near the / n-ZnO junction.
FIG. 7 shows epitaxial p-ZnRh in Example 2.₂O₄It is a graph which shows the current-voltage characteristic of a / n-ZnO junction diode.
FIG. 8 shows epitaxial p-ZnRh in Example 2.₂O₄It is a photoelectric conversion spectrum of a / n-ZnO junction diode.
9 is an X-ray amorphous p-ZnRh in Example 3. FIG.₂O₄/ Amorphous n-InGaZnO₄It is a schematic diagram which shows the element structure of a junction diode.
10 is an X-ray amorphous p-ZnRh in Example 3. FIG.₂O₄/ Amorphous n-InGaZnO₄It is a graph which shows the current-voltage characteristic of a junction diode.

Claims (7)

A PN junction device composed of an oxide semiconductor compound thin film and having a light detection function in the ultraviolet wavelength region, and exhibits n-type electrical conductivity epitaxially grown on an ITO single crystal film used as an n-type transparent electrode. Sensitive Zn _x Mg _1-x O (where 0.7 <x ≦ 1) single crystal thin film, diffusion treatment by annealing deposited as a polycrystalline or amorphous film on the Zn _x Mg _1-x O single crystal thin film A ZnO single crystal thin film containing 10 to 30 at% of Li ions exhibiting p-type conductivity epitaxially grown by a metal film or an ITO thin film used as a p-type electrode formed on the NiO single crystal thin film, the Zn PN of the NiO single crystal thin film containing _x Mg _{1-x O} single crystal thin film and the Li ions and wherein the forming a heteroepitaxial interface If device. A PN junction device composed of an oxide semiconductor compound thin film and having a light detection function in the ultraviolet wavelength region, and exhibits n-type electrical conductivity epitaxially grown on an ITO single crystal film used as an n-type transparent electrode. Sensitive Zn _x Mg _1-x O (where 0.7 <x ≦ 1) single crystal thin film, diffusion treatment by annealing deposited as a polycrystalline or amorphous film on the Zn _x Mg _1-x O single crystal thin film A ZnRh ₂ O ₄ single crystal thin film exhibiting p-type conductivity epitaxially grown by the above, a metal film used as a p-type electrode formed on the ZnRh ₂ O ₄ single crystal thin film, or an ITO thin film, and the Zn _x Mg A PN junction device, wherein a _1- xO single crystal thin film and the ZnRh ₂ O ₄ single crystal film form a heteroepitaxial interface. A PN junction device composed of an oxide semiconductor compound thin film and having a photodetection function in the ultraviolet wavelength range, and exhibits n-type electrical conductivity deposited on an ITO film used as an n-type transparent electrode, and exhibits ultraviolet sensitivity. An amorphous InGaO ₃ (ZnO) _m (m is an integer of 1 to less than 50) thin film, an amorphous NiO thin film or an amorphous ZnRh ₂ O ₄ thin film showing p-type conductivity deposited on the InGaO ₃ (ZnO) _m , It consists of a metal film or ITO thin film used as a p-type electrode formed on the amorphous NiO thin film or amorphous ZnRh ₂ O ₄ thin film, and the amorphous InGaO ₃ (ZnO) _m (m is an integer of 1 to less than 50) this thin film and the amorphous NiO thin film or amorphous ZnRh ₂ O ₄ and the thin film forms a hetero-interface PN junction device according to claim. A method of manufacturing a PN junction device having an ultraviolet wavelength region photodetection function composed of an oxide semiconductor compound thin film, wherein a Zn _x Mg _1-x O single crystal thin film is epitaxially grown on an ITO single crystal film, and the Zn A polycrystalline or amorphous NiO thin film containing 10-30 at% of Li ions is deposited on a single crystal thin film of _x Mg _1-x O (0.7 <x ≦ 1) and annealed at a temperature of 600 ° C. to 1500 ° C. The polycrystalline or amorphous NiO thin film is made into a NiO single crystal thin film by performing epitaxial growth by diffusion treatment, and a heteroepitaxial interface between the Zn _x Mg _1-x O single crystal thin film and the NiO single crystal thin film is formed. A metal film or an ITO thin film is formed on the NiO single crystal thin film. Method. A method of manufacturing a PN junction device having a light detection function in an ultraviolet wavelength region composed of an oxide semiconductor compound thin film, wherein Zn _x Mg _1-x O (where 0.7 <x ≦ 1) Epitaxially grow a single crystal thin film, deposit a polycrystalline or amorphous ZnRh ₂ O ₄ film on the Zn _x Mg _1-x O single crystal thin film, and perform diffusion treatment by annealing at a temperature of 600 ° C. to 1500 ° C. By epitaxially growing the polycrystalline or amorphous ZnRh ₂ O ₄ film into a ZnRh ₂ O ₄ single crystal thin film, the Zn _x Mg _1-x O single crystal thin film and the ZnRh ₂ O ₄ single crystal thin film are heteroepitaxially formed. surfactant to form, PN contact of claim 2, wherein the forming a metal film or thin ITO film on the ZnRh ₂ O ₄ single crystal thin film A device manufacturing method. A method of manufacturing a PN junction device having an ultraviolet wavelength region photodetection function composed of an oxide semiconductor compound thin film, wherein an amorphous InGaO ₃ (ZnO) _m (m is an integer of 1 to less than 50) thin film on an ITO film Then, an amorphous NiO thin film or an amorphous ZnRh ₂ O ₄ thin film is deposited on the InGaO ₃ (ZnO) _m thin film at a substrate temperature of 100 ° C. or less, and the amorphous InGaO ₃ (ZnO) thin film and the amorphous NiO thin film or amorphous ZnRh are deposited. forming a hetero interface between the ₂ O ₄ thin film, method of manufacturing a PN junction device according to claim 3, wherein the forming a metal film or thin ITO film on the amorphous NiO thin film or amorphous ZnRh ₂ O ₄ thin film . A photodetector having selective sensitivity in the ultraviolet wavelength region using the PN junction device according to claim 1.

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