A function-switchable oxide heterojunction photodiode and a preparation method thereof

Abstract

The application relates to the field of semiconductor devices and discloses a function-switchable oxide heterojunction photodiode and a preparation method, which comprises an insulating substrate, an N-type oxide semiconductor and a P-type semiconductor arranged in sequence; the interface of the P-type semiconductor and the N-type oxide semiconductor forms a type-II band contact hetero-PN junction; the insulating substrate and the N-type oxide semiconductor are laminated; the P-type semiconductor is partially deposited on the N-type oxide semiconductor; and a metal electrode comprises a P-type ohmic electrode and an N-type ohmic electrode, the P-type ohmic electrode is located on the P-type semiconductor, and the N-type ohmic electrode is located on the N-type oxide semiconductor. The application uses the P-type semiconductor and the N-type oxide semiconductor to construct a heterojunction, uses the characteristics of naturally capturing or releasing carriers of the oxygen vacancy defect level in the oxide semiconductor under bias to convert the electrical characteristics of the heterojunction, and realizes the switching of the photoelectric detection and sensing functions of the device.

Description

Technical Field

[0001] This invention relates to the field of semiconductor devices, and more particularly to a functionally switchable oxide heterojunction photodiode and its fabrication method. Background Technology

[0002] With the emergence of new application scenarios such as smart homes, the demand for multifunctional devices is increasing. Traditional photodetectors can only achieve a single detection function. Although interconnecting with other functional devices or packaging them on the same chip can achieve multiple functions, the coupling between modules increases chip latency, power consumption, and area, which is detrimental to chip integration and miniaturization. In the era of big data, the demand for multifunctional integrated devices is increasing. Traditional multifunctional devices are implemented by integrating different functional units such as detectors onto the same chip through external circuit interconnection or packaging technology, which greatly restricts the development of chip integration.

[0003] In recent years, the excellent properties of two-dimensional materials have provided a material basis for realizing multifunctional devices. By constructing two-dimensional material heterojunctions and applying appropriate excitation, dual functions can be superimposed in a single device, such as ReS2 / WSe2 heterojunction, MoTe2 / MoS2 heterojunction, and graphene / PEIE (polyetherimide) / organic heterojunction (O-BHJ) multilayer heterojunction. The switching between photoelectric detection and other functions can be achieved through gate voltage modulation and wavelength modulation.

[0004] For example, the prior art CN202110550031.4 discloses a composition of silicon carbide, monolayer graphene, gallium oxide and electrodes, wherein the monolayer graphene is disposed between the silicon carbide and the gallium oxide, and there are two electrodes, both of which are in contact with the monolayer graphene.

[0005] For existing interconnection / integration schemes of different functional units, interconnecting or integrating discrete devices introduces coupling problems, leading to delays and other issues that negatively impact device response speed. Furthermore, interconnected or integrated chips will have greater power consumption and area, hindering the development of low-power and small-size chips.

[0006] For reconfigurable devices based on two-dimensional materials, despite their excellent material properties, there is still considerable room for improvement in the stability and reliability of current two-dimensional materials. Furthermore, device fabrication methods, such as dry and wet transfer, suffer from varying degrees of repeatability, uncontrollable interface quality, and low yield, which are not conducive to large-scale production. Summary of the Invention

[0007] This invention addresses the problems of signal delay, increased power consumption, and uncontrollable fabrication process, poor uniformity, and low yield of two-dimensional materials caused by single-function device coupling in the prior art. It provides a switchable oxide heterojunction photodiode and its fabrication method.

[0008] To solve the above-mentioned technical problems, the present invention provides the following technical solution:

[0009] A switchable oxide heterojunction photodiode includes an insulating substrate, an N-type oxide semiconductor, and a P-type semiconductor arranged sequentially; the interface between the P-type semiconductor and the N-type oxide semiconductor forms a type II band contact heterojunction.

[0010] An insulating substrate and an N-type oxide semiconductor are stacked together.

[0011] P-type semiconductors are locally deposited on N-type oxide semiconductors;

[0012] It also includes metal electrodes; the metal electrodes include P-type ohmic electrodes and N-type ohmic electrodes, with the P-type ohmic electrodes located on a P-type semiconductor and the N-type ohmic electrodes located on an N-type oxide semiconductor.

[0013] Preferably, the N-type oxide semiconductor is an N-type oxide semiconductor with tunable oxygen defects.

[0014] Preferably, N-type oxide semiconductors include zinc oxide (ZnO), indium tin oxide (ITO), and gallium oxide (Ga2O3).

[0015] Preferably, the thickness of the N-type oxide semiconductor is 100 nm to 300 nm.

[0016] Preferably, the insulating substrate is a rigid insulating substrate or a flexible insulating substrate; the insulating substrate includes sapphire Al2O3, iron-doped gallium oxide, mica, and polyimide film.

[0017] Preferably, the P-type semiconductor includes nickel oxide (NiO) and tin oxide (SnO); the thickness of the P-type semiconductor layer is 30 nm to 80 nm.

[0018] To address the aforementioned technical problems, this invention also provides a method for fabricating a functionally switchable oxide heterojunction photodiode, which is used to fabricate the aforementioned functionally switchable oxide heterojunction photodiode. The method includes:

[0019] N-type oxide semiconductor is epitaxially grown on the surface of an insulating substrate;

[0020] Local deposition of P-type semiconductor on N-type oxide semiconductor;

[0021] Metal electrodes are fabricated on the top of an N-type oxide semiconductor and a P-type semiconductor. The metal electrodes include a P-type ohmic electrode and an N-type ohmic electrode. The P-type ohmic electrode is located on the P-type semiconductor, and the N-type ohmic electrode is located on the N-type oxide semiconductor, thus completing the fabrication of a PN heterojunction diode.

[0022] Preferably, the methods used to epitaxially grow N-type oxide semiconductors on the surface of an insulating substrate include magnetron sputtering, metal-organic chemical vapor deposition (MOCVD), hydride vapor phase epitaxy (HVPE), or plasma-enhanced chemical vapor deposition (PECVD).

[0023] Preferably, the methods used to locally deposit P-type semiconductors on N-type semiconductors include metal-organic vapor phase epitaxy (MOCVD), electron beam evaporation, or magnetron sputtering.

[0024] Preferably, metal electrodes are fabricated on the top of N-type oxide semiconductors and P-type semiconductors, and the metal electrodes are fabricated by methods including magnetron sputtering or electron beam evaporation.

[0025] This invention, by adopting the above technical solutions, has significant technical effects:

[0026] This invention utilizes the carrier capture and release capability of the vacancy defect energy level in oxide to design a heterojunction diode whose photoelectric properties can be switched according to the external bias voltage, thereby realizing a multifunctional optoelectronic device.

[0027] This invention uses P-type semiconductors and N-type oxide semiconductors to construct a heterojunction. It utilizes the characteristic of the natural oxygen vacancy defect energy level in the oxide semiconductor to capture or release charge carriers under bias voltage to convert the electrical characteristics of the heterojunction and realize the switching between photoelectric detection and sensing functions of the device.

[0028] The oxygen vacancy defects in the N-type oxide semiconductor of this invention can be controlled by the growth process (oxygen content ratio) to achieve further performance optimization.

[0029] Compared to traditional interconnect or packaged devices, this invention achieves dual-function integration in a single device, which will benefit the development of chip integration and miniaturization in terms of response speed, power consumption, and area.

[0030] The oxide heterojunction of this invention can achieve bias-controlled switching of operating modes, realize dual-function integration of a single device, reduce chip area and signal conversion loss, improve collaborative efficiency, and reduce power consumption and cost.

[0031] The oxide heterojunction of the present invention can be directly prepared by silicon-based compatible processes such as magnetron sputtering. The surface properties of gallium oxide and oxygen vacancies can be precisely controlled by doping, annealing, and interface modification (such as dry / wet processing), which has excellent interface control capability. Moreover, the preparation process is mature and stable, with high yield and good mass production potential.

[0032] The semiconductor process involved in this invention is compatible with CMOS. Compared with two-dimensional material reconfigurable devices, the fabrication process is mature and stable, with high yield and mass production capability. Attached Figure Description

[0033] Figure 1 This is a schematic diagram of the oxide heterojunction diode structure of the present invention.

[0034] Figure 2 This is a schematic diagram showing the misaligned arrangement of the conduction band and valence band in this invention.

[0035] Figure 3-1 This is a schematic diagram of the reverse bias applied according to the present invention. Figure 3-2 This is a schematic diagram of the positive bias applied in this invention.

[0036] Figure 4 -a is a schematic diagram of the cleaning and drying substrate for the preparation of oxide heterojunction diodes according to the present invention.

[0037] Figure 4 -b is a schematic diagram of the deposition of N-type oxide semiconductor gallium oxide in the fabrication of oxide heterojunction diodes according to the present invention.

[0038] Figure 4 -c is a schematic diagram of the deposition of P-type semiconductor nickel oxide in the preparation of oxide heterojunction diodes according to the present invention.

[0039] Figure 4 -d is a schematic diagram of the coating process for the oxide heterojunction diode prepared according to the present invention.

[0040] Figure 4 -e is a schematic diagram of the exposure and development of oxide heterojunction diodes prepared according to the present invention.

[0041] Figure 4 -f is a schematic diagram of the deposition of N-type ohmic electrodes for the preparation of oxide heterojunction diodes according to the present invention.

[0042] Figure 4 -g is a schematic diagram of the removal of adhesive during the fabrication of oxide heterojunction diodes according to the present invention.

[0043] Figure 4 -h is a schematic diagram of the coating process for the oxide heterojunction diode prepared according to the present invention.

[0044] Figure 4 -i is a schematic diagram of the exposure and development of oxide heterojunction diodes prepared according to the present invention.

[0045] Figure 4 -j is a schematic diagram of the deposition of a P-type ohmic electrode for the preparation of an oxide heterojunction diode according to the present invention.

[0046] Figure 4 -k is a schematic diagram of the removal of adhesive during the fabrication of the oxide heterojunction diode according to the present invention.

[0047] Among them, 1—substrate, 2—N-type oxide semiconductor, 3—P-type semiconductor, 4—metal electrode, 5—photoresist, 41—P-type ohmic contact electrode, and 42—N-type ohmic contact electrode. Detailed Implementation

[0048] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments.

[0049] Example 1

[0050] An oxide heterojunction diode with switchable photodetection and sensing functions includes a substrate, an N-type oxide semiconductor, a P-type semiconductor, and a metal electrode.

[0051] An N-type oxide semiconductor is disposed on a substrate; a P-type semiconductor is disposed on top of the N-type oxide semiconductor; the P-type semiconductor and the N-type oxide semiconductor are in contact to form a PN junction; and electrodes are disposed on the P-type semiconductor and the N-type oxide semiconductor.

[0052] The substrate provides mechanical support, lattice matching conditions required for the growth of N-type oxide semiconductors, and electrical insulation.

[0053] N-type oxide semiconductors have defect levels introduced by natural oxygen vacancies. These defect levels are located 1.0-1.3 eV below the conduction band. They trap photogenerated electrons as trap states or intermediate states, forming stagnant states to support changes in the electrical properties of the heterojunction.

[0054] The oxygen vacancy defect energy level in N-type oxide semiconductors can be tuned through growth processes / interface modification processes.

[0055] P-type semiconductors and N-type oxide semiconductors form a type II band contact heterojunction to maximize the separation, transport and collection of photogenerated carriers;

[0056] The electrodes form ohmic contacts with the P-type semiconductor and the N-type oxide semiconductor respectively, without introducing additional resistance.

[0057] exist Figure 1 A heterojunction diode based on oxide semiconductor was designed. The heterojunction diode based on oxide semiconductor uses a heterojunction constructed from P-type semiconductor and N-type oxide semiconductor.

[0058] Figure 2 In, among which, E V E is the top energy level of the valence band. C For the bottom energy level of the conduction band, E FThe heterojunction, constructed from P-type and N-type oxide semiconductors, is a type II bandgap contact. The conduction and valence bands of the two materials are misaligned, leading to electron depletion in the N-type oxide semiconductor and migration into the P-type semiconductor, and hole depletion in the P-type semiconductor and migration into the N-type semiconductor. Electrons and holes are physically isolated on opposite sides of the heterojunction, effectively reducing carrier recombination probability and increasing photogenerated carrier lifetime. Simultaneously, the built-in electric field accelerates photogenerated carrier separation, improving photocurrent collection efficiency. The N-type oxide semiconductor contains natural oxygen vacancies, forming defect levels. These defect levels can trap or release carriers, resulting in different electrical properties on the heterojunction surface. By applying an external bias voltage to the heterojunction and controlling the relative dominance of the built-in electric field and defect levels in carrier transport, different device operating modes can be achieved.

[0059] The first working mode is the detection mode. Figure 3-1 In, among which, E V E is the top energy level of the valence band. C Here, hv is the bottom energy level of the conduction band, and E is the photon energy. L The energy level is a defect level; when a reverse bias is applied, the depletion region widens further, the photoresponse is enhanced, and the increased electric field promotes the efficient separation, transport and collection of photogenerated carriers, improving the response speed of the device and thus exhibiting photoelectric detection function.

[0060] The second working mode is the sensor-based calculation mode. Figure 3-2 In, among which, E V E is the top energy level of the valence band. C Here, hv is the bottom energy level of the conduction band, and E is the photon energy. L The defect energy level is at the point where a forward bias voltage is applied. This weakens the built-in electric field in the heterojunction, lowering the barrier height and facilitating carrier injection. In this state, defects such as oxygen vacancies in the N-type oxide semiconductor dominate the capture and release of carriers, leading to a significantly enhanced sustained photoconductivity effect. This results in multi-level conductivity states and a longer holding time, thus enabling photoelectric sensing and computing functions.

[0061] The thickness of the N-type semiconductor layer is 100 ~ 300 nm to ensure the quality of the gallium oxide film and the photon absorption efficiency; the thickness of the P-type semiconductor layer is 30 ~ 80 nm to reduce the extinction rate while ensuring material quality.

[0062] Example 2

[0063] Based on Example 1, this example describes a method for fabricating an oxide heterojunction diode with switchable photodetection and sensing functions, comprising:

[0064] Step 1: Clean the insulating substrate

[0065] A 400 μm thick sapphire Al2O3 substrate was sequentially ultrasonically cleaned in acetone, isopropanol, and deionized water for 10 minutes each. After cleaning, the substrate was dried by purging with nitrogen gas. Figure 4 -a.

[0066] Step 2: Deposit N-type gallium oxide

[0067] Using radio frequency magnetron sputtering, under conditions of 100W sputtering power, a pure argon atmosphere (60 sccm), and a pressure of 8 mTorr, a 180 nm thick N-type gallium oxide layer was grown on a sapphire Al₂O₃ substrate 1 using a high-purity (99.99%) gallium oxide target. Figure 4 -b.

[0068] Step 3: Deposit P-type nickel oxide

[0069] Using magnetron sputtering, a 50 nm thick layer of P-type nickel oxide 3 was grown on N-type gallium oxide 2 using a high-purity (99.99%) nickel oxide target under conditions of 90 W RF power, a mixed atmosphere of oxygen (20 sccm) and argon (40 sccm), and a pressure of 6 mTorr. Figure 4 -c.

[0070] Step 4: Forming metal electrodes

[0071] Photoresist is spin-coated, exposed to ultraviolet light, and developed to form a mask. Ti / Au multilayer metal electrodes are deposited using electron beam evaporation. Excess photoresist and metal are removed by a lift-off process, and annealing in nitrogen at 470°C forms ohmic electrodes. Figure 4 -d、 Figure 4 -e、 Figure 4 -f and Figure 4 -g.

[0072] Step 5: Forming metal electrodes

[0073] Similar to step 4, a Ni / Au multilayer metal is deposited as an ohmic electrode through photolithography and electron beam evaporation processes, such as... Figure 4 -h、 Figure 4 -i、 Figure 4 -j and Figure 4 -k.

[0074] Example 3

[0075] Based on Example 1, this example describes a method for fabricating an oxide heterojunction diode with switchable photodetection and sensing functions, comprising:

[0076] Step 1: Clean the insulating substrate

[0077] The C-side sapphire substrate was ultrasonically cleaned in acetone, isopropanol, and deionized water for 10 minutes each, and then dried by blowing with nitrogen gas.

[0078] Step 2: Deposit N-type gallium oxide

[0079] Using radio frequency magnetron sputtering, under conditions of 200W sputtering power, Ar / O2 (95sccm / 5sccm) deposition atmosphere and 0.7Pa pressure, a high-purity (99.99%) gallium oxide target was deposited for 60 min to grow an N-type gallium oxide with a thickness of 120nm on the substrate, followed by annealing in air at 800℃.

[0080] Step 3: Deposit P-type nickel oxide

[0081] Using magnetron sputtering, a 50 nm thick layer of P-type nickel oxide was grown on N-type gallium oxide using a high-purity (99.99%) nickel oxide target under conditions of 200 W RF power, a mixed atmosphere of oxygen (35 sccm) and argon (35 sccm) and a pressure of 0.6 Pa.

[0082] Step 4: Forming metal electrodes

[0083] Photoresist is spin-coated, exposed to ultraviolet light, and developed to form a mask. Ti / Au stacked metal electrodes are deposited using electron beam evaporation. Excess photoresist and metal are removed by a stripping process, and annealing is performed in nitrogen to form ohmic electrodes.

[0084] Step 5: Forming metal electrodes

[0085] Similar to step 4, Ni / Au multilayer metal is deposited as an ohmic electrode through photolithography and electron beam evaporation processes.

Claims

1. A function-switchable oxide heterojunction photodiode, comprising an insulating substrate, an N-type oxide semiconductor and a P-type semiconductor arranged in sequence; characterized in that: an interface between the P-type semiconductor and the N-type oxide semiconductor forms a type-II band contact hetero-PN junction, and the N-type oxide semiconductor has adjustable oxygen vacancy defects, and the concentration of the oxygen vacancy defects is adjusted by adjusting the oxygen partial pressure; the insulating substrate and the N-type oxide semiconductor are laminated; the P-type semiconductor is deposited on the N-type oxide semiconductor; and the function-switchable oxide heterojunction photodiode further comprises a metal electrode, wherein the metal electrode comprises a P-type ohmic electrode and an N-type ohmic electrode, the P-type ohmic electrode is located on the P-type semiconductor, and the N-type ohmic electrode is located on the N-type oxide semiconductor. The N-type oxide semiconductor comprises zinc oxide (ZnO), indium tin oxide (ITO) or gallium oxide (Ga2O3). The thickness of the N-type oxide semiconductor is 100 nm to 300 nm. The insulating substrate is a rigid insulating substrate or a flexible insulating substrate, and the insulating substrate comprises sapphire (Al2O3), iron-doped gallium oxide, mica or a polyimide film. The P-type semiconductor comprises nickel oxide (NiO) or stannous oxide (SnO), and the thickness of the P-type semiconductor layer is 30 nm to 80 nm.

2. The functionally switchable oxide heterojunction photodiode of claim 1, wherein, A method for preparing the function-switchable oxide heterojunction photodiode according to any one of claims 1 to 5, comprising the following steps: epitaxially growing an N-type oxide semiconductor on the surface of an insulating substrate, wherein the N-type oxide semiconductor has adjustable oxygen vacancy defects, and the concentration of the oxygen vacancy defects is adjusted by adjusting the oxygen partial pressure; depositing a P-type semiconductor on the N-type semiconductor; and preparing a metal electrode on the top of the N-type oxide semiconductor and the P-type semiconductor, wherein the metal electrode comprises a P-type ohmic electrode and an N-type ohmic electrode, the P-type ohmic electrode is located on the P-type semiconductor, and the N-type ohmic electrode is located on the N-type oxide semiconductor.

3. The functionally switchable oxide heterojunction photodiode of claim 1, wherein, The method for epitaxially growing the N-type oxide semiconductor on the surface of the insulating substrate comprises magnetron sputtering, metal organic chemical vapor deposition (MOCVD), hydride vapor phase epitaxy (HVPE) or plasma enhanced chemical vapor deposition (PECVD).

4. The functionally switchable oxide heterojunction photodiode of claim 1, wherein, The method for depositing the P-type semiconductor on the N-type semiconductor comprises metal organic vapor phase epitaxy (MOCVD), electron beam evaporation or magnetron sputtering.

5. The functionally switchable oxide heterojunction photodiode of claim 1, wherein, The method for preparing the metal electrode on the top of the N-type oxide semiconductor and the P-type semiconductor comprises magnetron sputtering or electron beam evaporation.

6. A method for fabricating a functionally switchable oxide heterojunction photodiode, comprising: ​ ​ ​ ​ 7. The method of claim 6, wherein the method further comprises: ​ 8. The method of claim 6, wherein the method further comprises: ​ 9. The method of claim 6, wherein the method further comprises: ​

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