Photodetector based on negative photoconductivity of heterostructure band engineering
By designing a heterostructure of wide-bandgap photosensitive material and narrow-bandgap two-dimensional channel material in optoelectronic devices, and controlling the carrier concentration by photogenerated carrier injection, the problems of poor repeatability and consistency of existing negative photoconductive devices are solved, and a stable and tunable negative photoconductive effect is achieved, which is suitable for new information processing systems.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- QIANYUAN NATIONAL LABORATORY
- Filing Date
- 2026-05-11
- Publication Date
- 2026-06-05
AI Technical Summary
Existing negative photoconductive devices rely on internal defect states of materials, grating control effects, or complex structures, resulting in poor repeatability and consistency, making it difficult to achieve stable and predictable negative light response. Furthermore, their fabrication is difficult, limiting their application in large-scale arrays and practical systems.
By selecting a wide-bandgap photosensitive material at a specific Fermi level position and forming a reverse bandgap two-dimensional channel material to form a heterostructure, and by using photogenerated carrier injection to control the carrier concentration of the narrow-bandgap two-dimensional channel material, a stable and repeatable negative photoconductivity effect can be achieved.
It achieves a stable and repeatable negative photoconductivity response, reduces dependence on material defects, simplifies device structure, and improves controllability and integrability, making it suitable for integrated sensing, storage, and computing systems, optical logic circuits, and neuromorphic computing systems.
Smart Images
Figure CN122161183A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of optoelectronic devices and semiconductor heterogeneous integration technology, specifically relating to a negative photoconductive optoelectronic device based on heterogeneous structure bandgap engineering control. Background Technology
[0002] The photoconductivity effect is one of the most fundamental and universal physical phenomena in optoelectronic devices. Essentially, it is the conversion of photon energy into electrical transport, a crucial mechanism connecting optical excitation and electrical response. Under illumination, traditional photoconductor devices absorb photons to excite electron transitions, generating photogenerated electron-hole pairs. This significantly increases the carrier concentration and mobility in the material, ultimately resulting in enhanced device conductivity—the typical positive photoconductivity effect. This process has advantages such as intuitive response and clear mechanism, making it fundamental and crucial in fields like optical detection, optical communication, image sensing, and even high-sensitivity imaging, forming a vital pillar of modern optoelectronic technology.
[0003] However, as information processing paradigms evolve from traditional separate architectures to an integrated model deeply merging sensing, storage, and computing, the single positive photoconductivity response has gradually revealed its functional limitations. In integrated sensing-storage-computing devices, the system not only needs the positive modulation capability of light-enhanced conductivity but also the reverse modulation mechanism of light-suppressed conductivity to achieve key operations such as logic reversal, weight decay, and information erasure. In neuromorphic computing systems, inhibitory synapses in biological neural networks are crucial for maintaining network stability, enhancing contrast, and preventing signal saturation. At the device level, this requires a negative response behavior that enables a decrease in conductivity due to light input. Therefore, the negative photoconductivity effect has gradually evolved into a key physical function supporting new computing paradigms.
[0004] Currently reported negative photoconductive devices mostly rely on defect states within the material, grating control effects, interfacial adsorption / desorption processes, or complex multilayer coupling effects to achieve their negative photoresponse. Their negative photoresponse typically originates from a decrease in effective carrier concentration caused by the capture of photogenerated carriers, or from accidental results due to interfacial state modulation. On the one hand, device performance is highly sensitive to material growth quality and defect distribution, resulting in poor repeatability and consistency. On the other hand, the negative photoresponse process lacks clear design parameters and predictability, making engineering control difficult. Furthermore, the complex implementation structure significantly increases fabrication difficulty and system integration costs, limiting their application potential in large-scale arrays and practical systems.
[0005] In contrast, achieving designable control of charge carriers through specific bandgap engineering is a more promising approach. By precisely selecting semiconductor materials with different bandgap widths, electron affinity, and Fermi level positions, and constructing controllable bandgap alignment at the interface, stable and tunable band bending and built-in electric fields can be formed. This not only effectively controls the separation, recombination, and transport paths of photogenerated carriers but also provides new physical space for achieving negative photoresponse, thus realizing stable and repeatable negative photoconductivity. However, an integrated design guideline from material selection and interface design to performance control has not yet been established. Therefore, inventing a negative photoconductivity effect with a clear and universal mechanism would not only help overcome the dependence of existing devices on defect states and interface states but also potentially provide an engineering solution for next-generation optoelectronic fusion devices. Summary of the Invention
[0006] In view of the above, the purpose of this invention is to provide a negative photoconductive optoelectronic device based on heterostructure bandgap engineering control. This is achieved by selecting a wide-bandgap photosensitive material with a specific Fermi level position relationship and a narrow-bandgap two-dimensional channel material to form an inverted interface bandgap bending heterostructure. Under illumination, majority carriers from the wide-bandgap photosensitive material are injected into the narrow-bandgap two-dimensional channel material and recombine with the majority carriers in the narrow-bandgap two-dimensional channel material. By controlling the overall carrier concentration of the narrow-bandgap two-dimensional channel material, a stable, repeatable, and defect-independent negative photoconductive response is achieved, providing a new approach for the reliable fabrication of this type of device. This device can be applied to novel information processing fields such as integrated image recognition systems, optical logic circuits, photosynaptic devices, and neuromorphic computing systems.
[0007] To achieve the above-mentioned objectives, an embodiment provides a negative photoconductive optoelectronic device based on heterostructure bandgap engineering control, comprising: a substrate, a wide bandgap photosensitive material layer disposed on the substrate, a narrow bandgap two-dimensional channel material layer disposed on the wide bandgap photosensitive material layer, and a source electrode and a drain electrode disposed on the surface of the narrow bandgap two-dimensional channel material layer, wherein the source electrode is used to inject charge carriers into the channel layer and cooperates with the drain electrode to realize the modulation and readout of the channel current; By utilizing a wide-bandgap photosensitive material layer with a specific difference in Fermi level and a narrow-bandgap two-dimensional channel material layer, a band-bending heterojunction with reversed bandgap is formed. Under illumination, most of the photogenerated carriers generated by the wide bandgap photosensitive material layer are injected into the narrow bandgap two-dimensional channel material layer, thereby reducing the effective carrier concentration of the narrow bandgap two-dimensional channel material layer, reducing the overall current of the device, and thus achieving a negative photoconductivity effect.
[0008] A wide-bandgap photosensitive material layer and a narrow-bandgap two-dimensional channel material layer form a heterostructure. When the two different semiconductors come into contact, charge redistribution occurs near the interface to achieve Fermi level equilibrium, forming a built-in electric field and causing band bending. Under illumination, photogenerated electrons and holes migrate to lower energy directions under the influence of the built-in electric field, achieving effective separation of photogenerated carriers.
[0009] The narrow bandgap two-dimensional channel material layer constitutes the main current transport channel of the device; the wide bandgap photosensitive material layer does not participate in current transport, but under the action of the built-in electric field at the heterojunction interface, it injects photogenerated carriers into the narrow bandgap two-dimensional channel material layer, reduces the current of the narrow bandgap two-dimensional channel material layer, and realizes the negative photoconductivity effect.
[0010] Negative photoconductive optoelectronic devices achieve negative photoconductivity through source and drain electrodes. The specific working mechanism is as follows: In the absence of light, the narrow-bandgap two-dimensional channel material layer forms a stable conductive channel under the bias voltage of the source and drain electrodes, and the device exhibits normal conduction characteristics. Under illumination, the wide-bandgap photosensitive material layer absorbs photons and generates photogenerated carriers with the opposite majority carrier type to those in the narrow-bandgap two-dimensional channel material layer. These photogenerated carriers are injected into the narrow-bandgap two-dimensional channel material layer under the drive of the built-in electric field at the interface, recombine with the majority carriers of the narrow-bandgap two-dimensional channel material layer, reducing the carrier concentration and current of the two-dimensional channel material layer, thus achieving the negative photoconductivity effect.
[0011] Preferably, the thickness of the narrow bandgap two-dimensional channel material layer should be less than 50 nm, and its current in a dark environment should be more than 10 times that of the wide bandgap photosensitive material layer.
[0012] Preferably, when the wide-bandgap photosensitive material layer is an n-type semiconductor and the narrow-bandgap two-dimensional channel material layer is a p-type semiconductor, the Fermi level of the p-type semiconductor should be higher than that of the n-type semiconductor, and the difference between their Fermi levels should be ≥0.05 eV. Under illumination, photogenerated electrons generated by the n-type semiconductor in the wide-bandgap photosensitive material layer are injected into the narrow-bandgap two-dimensional channel material layer under the influence of the built-in electric field at the heterojunction interface, reducing the effective carrier concentration of the narrow-bandgap two-dimensional channel material layer and achieving a negative photoconductivity effect.
[0013] Preferably, when the wide-bandgap photosensitive material layer is a p-type semiconductor and the narrow-bandgap two-dimensional channel material layer is an n-type semiconductor, the Fermi level of the n-type semiconductor should be lower than that of the p-type semiconductor, and the difference between their Fermi levels should be ≥0.05 eV. Under illumination, photogenerated holes generated by the p-type semiconductor in the wide-bandgap photosensitive material layer are injected into the narrow-bandgap two-dimensional channel material layer under the influence of the built-in electric field at the heterojunction interface, reducing the effective carrier concentration of the narrow-bandgap two-dimensional channel material layer and achieving a negative photoconductivity effect.
[0014] The semiconductor conductivity type of the wide-bandgap photosensitive material layer is opposite to that of the narrow-bandgap two-dimensional channel material layer, and the Fermi level of the p-type semiconductor needs to be higher than that of the n-type semiconductor. The resulting built-in electric field direction is conducive to the flow of photogenerated carriers generated by the wide-bandgap photosensitive material layer to the narrow-bandgap two-dimensional channel material layer under illumination, and recombine with the majority carriers in the narrow-bandgap two-dimensional channel material layer to reduce the current and achieve a negative photoconductivity effect.
[0015] Preferably, the band gap of the narrow band gap two-dimensional channel material layer semiconductor should be between 0.1 eV and 1.0 eV, and the material is selected from two-dimensional black phosphorus, transition metal chalcogenides, or other narrow band gap two-dimensional semiconductors with comparable band gaps.
[0016] Preferably, the band gap of the wide bandgap photosensitive material layer semiconductor should be between 2.0 eV and 6.0 eV, and the material is selected from gallium oxide, gallium nitride, zinc oxide, cuprous oxide, diamond, or other wide bandgap semiconductors with comparable band gaps.
[0017] Specifically, the material system exhibits scalability. For narrow-bandgap p-type two-dimensional channel materials, wide-bandgap photosensitive materials can be selected from wide-bandgap semiconductor materials such as gallium oxide, gallium nitride, and zinc oxide, which have relatively low Fermi levels. For narrow-bandgap n-type two-dimensional channel materials, wide-bandgap photosensitive materials can be selected from wide-bandgap semiconductor materials such as cuprous oxide and diamond, which have relatively high Fermi levels. Both material systems allow for effective modulation of the carrier concentration in the two-dimensional channel layer through photogenerated carrier injection and bandgap modulation within the heterostructure.
[0018] Compared with the prior art, the beneficial effects of the present invention include at least the following: A novel negative photoconductivity mechanism based on heterojunction bandgap engineering is proposed: the effective carrier concentration of a narrow-bandgap two-dimensional channel material is controlled by selectively injecting photogenerated carriers into a wide-bandgap photosensitive material, overcoming the limitations of traditional defect engineering or three-electrode schemes with a two-electrode structure. The negative photoconductivity effect is dominated by carrier transport in the narrow-bandgap two-dimensional channel material, rather than the photosensitive material itself. Selective injection of photogenerated electrons or holes is achieved through band bending. This mechanism is clear, highly stable, and applicable to n / p-type channel materials, with a wide range of applications. The Fermi level relationship is introduced into the device structure as a designable parameter, significantly improving the tunability and reproducibility of the negative photoconductivity effect. The device structure is simple and process-compatible, requiring only the formation of electrodes on the two-dimensional channel material, making it easy to integrate. It is suitable for novel information processing systems such as inductive-memory-computing integration, optical logic, and neuromorphic computing, and has good application prospects. Attached Figure Description
[0019] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0020] Figure 1 This is a schematic diagram of a device structure with negative photoconductivity provided in the embodiment, where 1 is an electrode; 2 is a narrow bandgap two-dimensional channel material layer; 3 is a wide bandgap photosensitive material layer; and 4 is a substrate. Figure 2 It shows the band structure before and after the formation of a heterojunction between an n-type wide-bandgap photosensitive material and a p-type narrow-bandgap two-dimensional material; Figure 3 It shows the band structure before and after the formation of a heterojunction between a p-type wide-bandgap photosensitive material and an n-type narrow-bandgap two-dimensional material; Figure 4 These are electron microscope images of gallium oxide / black phosphorus structures and corresponding band diagrams, where gallium oxide is a wide bandgap photosensitive material and black phosphorus is a narrow bandgap p-type two-dimensional material; Figure 5 This is the photocurrent curve of gallium oxide; Figure 6 This is the current-voltage curve of gallium oxide; Figure 7 It is the current in black phosphorus under dark conditions; Figure 8 The current-voltage curve of black phosphorus under dark conditions; Figure 9 This is the photocurrent curve of a gallium oxide / black phosphorus device; Figure 10 This is the current-voltage curve of a gallium oxide / black phosphorus device. Detailed Implementation
[0021] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and do not limit the scope of protection of this invention.
[0022] The embodiment provides a negative photoconductive optoelectronic device based on heterostructure bandgap engineering, such as... Figure 1As shown, the device includes: a substrate, a wide bandgap photosensitive material layer, a narrow bandgap two-dimensional channel material layer, and electrodes disposed on the surface of the narrow bandgap two-dimensional channel material layer. The wide bandgap photosensitive material layer and the narrow bandgap two-dimensional channel material layer form a heterojunction through contact. Through the matching design of their band structures and Fermi levels, when the device operates under illumination, photogenerated carriers generated by the wide bandgap photosensitive material layer are injected into the narrow bandgap two-dimensional channel material layer, thereby reducing the current in the narrow bandgap two-dimensional channel material layer and achieving a negative photoconductivity effect.
[0023] Figure 2 This is the band structure diagram before and after the formation of a heterojunction between an n-type wide-bandgap photosensitive material and a p-type narrow-bandgap two-dimensional channel material. Figure 2 The specific requirements and mechanisms for achieving negative photoconductivity are as follows: the Fermi level of the p-type narrow bandgap two-dimensional channel material must be higher than that of the n-type wide bandgap photosensitive material. The bandgap of the p-type narrow bandgap two-dimensional channel material is less than 1 eV, while the bandgap of the n-type wide bandgap photosensitive material is greater than 2 eV. When the two materials come into contact to form a heterostructure, a built-in electric field is formed at the interface, pointing from the p-type narrow bandgap two-dimensional channel material to the n-type wide bandgap photosensitive material, in order to achieve Fermi level equilibrium. Under illumination, under the influence of the built-in electric field, a large number of electrons generated by the n-type wide bandgap photosensitive material enter the p-type narrow bandgap two-dimensional channel material in the reverse direction, recombine with holes in the p-type narrow bandgap two-dimensional channel material, and reduce the current flowing through the p-type two-dimensional channel material. Because the bandgap of the p-type two-dimensional channel material is small and the current flowing through it is much greater than that of the n-type wide bandgap photosensitive material, the overall current of the device is dominated by the current of the p-type two-dimensional channel material, which exhibits a decrease under illumination.
[0024] Figure 3 This is the band structure diagram before and after a heterojunction is formed between a p-type wide-bandgap photosensitive material and an n-type narrow-bandgap two-dimensional material. Figure 3 The specific requirements and mechanisms for achieving negative photoconductivity are as follows: the Fermi level of the n-type narrow bandgap two-dimensional material must be lower than that of the p-type wide bandgap photosensitive material. The bandgap of the n-type narrow bandgap two-dimensional material must be less than 1 eV, while the bandgap of the p-type wide bandgap photosensitive material must be greater than 2 eV. After the two materials come into contact to form a heterostructure, an interface-built-in electric field is formed at the interface, pointing from the p-type wide bandgap photosensitive material to the n-type narrow bandgap two-dimensional material. Under illumination, photogenerated holes generated in the p-type wide bandgap photosensitive material enter the n-type narrow bandgap two-dimensional material in the reverse direction and recombine with electrons in the n-type narrow bandgap two-dimensional material, thus reducing the current flowing through the n-type narrow bandgap two-dimensional material. Because the bandgap of the n-type narrow bandgap two-dimensional material is small, and the current flowing through the n-type narrow bandgap two-dimensional material is much greater than the current flowing through the p-type wide bandgap photosensitive material, the overall current of the device is dominated by the current of the n-type narrow bandgap two-dimensional material, which exhibits a decrease under illumination.
[0025] Example 1: Negative photoconductive device based on gallium oxide / two-dimensional black phosphorus heterostructure Sapphire is used as the substrate to provide mechanical support and electrical isolation. A wide bandgap photosensitive material layer, a β-gallium oxide thin film with a bandgap wider than that of the two-dimensional channel material, is disposed on the substrate surface. A narrow bandgap two-dimensional channel material layer, a two-dimensional black phosphorus film, is disposed on the surface of the wide bandgap photosensitive material layer, serving as the main carrier transport channel for the device. Gold electrodes are selected for the source and drain electrodes, disposed on the surface of the two-dimensional black phosphorus film and forming ohmic contacts with it, to apply external bias and acquire the device current signal. The specific method is as follows: Using triethylgallium and oxygen as the reaction source, nitrogen as the carrier gas, and sapphire as the reaction substrate, a 300 nm thick β-gallium oxide thin film with a band gap of 4.9 eV was obtained by metal-organic chemical vapor deposition (MOCVD) at 650 °C for 3 h. The MOCVD-grown β-gallium oxide material (band gap 4.9 eV) was annealed at 800 °C in air for 30 min to control the reconstruction and partial passivation of donor defects, thereby reducing the carrier concentration and causing the β-gallium oxide material to transition from n-type to weakly n-type. This shifted the Fermi level to a position 0.1 eV–0.2 eV above the center of the band gap. At this point, the conduction band bottom (CBM), valence band top (VBM), and Fermi level of gallium oxide were located 4 eV, 8.9 eV, and 6.45 eV below the vacuum level, respectively. Black phosphorus was prepared mechanically. A two-dimensional black phosphorus material with a thickness of approximately 10 nm was selected and superimposed on a pre-prepared β-gallium oxide material. Black phosphorus is a p-type semiconductor material, with its CBM, VBM, and Fermi level located 6 eV, 6.3 eV, and 6.25 eV below the vacuum level, respectively. The Fermi level of p-type black phosphorus is higher than that of n-type gallium oxide, representing an anomalous Fermi level relationship, which meets the conditions for forming negative photoconductivity. Subsequently, two gold electrodes were fabricated on both sides of the black phosphorus using thermal evaporation. The resulting β-gallium oxide / two-dimensional black phosphorus heterostructure is shown below. Figure 4 The band structure of the gallium oxide / two-dimensional black phosphorus heterostructure is shown in the middle left figure. Figure 4 As shown in the middle right figure, gallium oxide and two-dimensional black phosphorus form a stable heterojunction energy band arrangement at the interface; photogenerated electrons generated by gallium oxide after being illuminated move towards black phosphorus under the influence of energy band bending.
[0026] Gallium oxide, as a wide-bandgap photosensitive material, has the following photoresponse capability: Figure 5 As shown, gallium oxide generates a photocurrent of about 5 nanoamps under illumination at a voltage of 0.01 volts. Figure 6 The current-voltage curves of gallium oxide are shown. At 0.5 volts, the photocurrent and dark current are 86 nanoamps and 0.01 nanoamps, respectively. This indicates that the current flowing through the two-dimensional material should be more than 5 times the photocurrent and more than 10 times the dark current, i.e., greater than 0.43 microamps. Two-dimensional black phosphorus is selected as a narrow bandgap two-dimensional semiconductor material, and its current dominates the magnitude of the device's on-state current. Figure 7As shown, at a voltage of 0.01 volts, the current flowing through the black phosphorus material layer is about 4 microamps, which is more than 5 times higher than the photocurrent flowing through the gallium oxide material and more than 10 times higher than the dark current flowing through the gallium oxide material. Figure 8 The current-voltage curves of black phosphorus were shown, further confirming that black phosphorus is a p-type semiconductor material with a conductivity far higher than that of gallium oxide.
[0027] When gallium oxide and black phosphorus are used to construct a heterostructure, the negative photoconductivity under illumination is as follows when a bias voltage of 0.5 volts is applied: Figure 9 As shown, the wide bandgap photosensitive material layer (gallium oxide) absorbs incident photons and generates photogenerated electrons and holes. Under the influence of the built-in electric field and band bending at the heterostructure interface, photogenerated carriers selectively migrate into the p-type two-dimensional channel material (black phosphorus), leading to a decrease in the effective hole concentration in the two-dimensional channel material. The device exhibits a stable negative photoconductivity effect, with the current in the dark being more than five times that under illumination. Figure 10 Further analysis using current-voltage curves confirmed that the negative photoconductivity effect resulted in a photocurrent significantly lower than the dark current within the -2V to 2V range, indicating that the device has high scalability.
[0028] The specific embodiments described above illustrate the technical solution and beneficial effects of the present invention in detail. It should be understood that the above description is only the most preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, additions, and equivalent substitutions made within the scope of the principles of the present invention should be included within the protection scope of the present invention.
Claims
1. A negative photoconductive optoelectronic device based on heterostructure bandgap engineering control, characterized in that, include: The substrate, a wide bandgap photosensitive material layer disposed on the substrate, a narrow bandgap two-dimensional channel material layer disposed on the wide bandgap photosensitive material layer, and a source electrode and a drain electrode disposed on the surface of the narrow bandgap two-dimensional channel material layer, wherein the source electrode is used to inject charge carriers into the channel layer and cooperates with the drain electrode to realize the modulation and reading of the channel current. By utilizing the specific difference in the Fermi level between the wide-bandgap photosensitive material layer and the narrow-bandgap two-dimensional channel material layer to form a band-bending heterojunction with opposite band offset, under illumination, most of the photogenerated carriers generated by the wide-bandgap photosensitive material layer are injected into the narrow-bandgap two-dimensional channel material layer, thereby reducing the effective carrier concentration of the narrow-bandgap two-dimensional channel material layer, reducing the overall current of the device, and thus achieving a negative photoconductivity effect.
2. The negative photoconductive optoelectronic device based on heterostructure bandgap engineering control according to claim 1, characterized in that, The narrow bandgap two-dimensional channel material layer is the main current transport channel of the device. Its thickness should be less than 50 nm, and its current in a dark environment should be more than 10 times that of the wide bandgap photosensitive material layer.
3. The negative photoconductive optoelectronic device based on heterostructure bandgap engineering control according to claim 1, characterized in that, By selecting the wide-bandgap photosensitive material layer and the narrow-bandgap two-dimensional channel material layer with a difference in Fermi level, a band-bending heterojunction with opposite band shifts is formed at their interface, including: When the wide bandgap photosensitive material layer is an n-type semiconductor and the narrow bandgap two-dimensional channel material layer is a p-type semiconductor, the Fermi level of the p-type semiconductor should be higher than that of the n-type semiconductor, and the difference between their Fermi levels should be ≥0.05 eV.
4. The negative photoconductive optoelectronic device based on heterostructure bandgap engineering control according to claim 3, characterized in that, Under illumination, photogenerated electrons generated by the n-type semiconductor in the wide bandgap photosensitive material layer are injected into the p-type semiconductor in the narrow bandgap two-dimensional channel material layer under the action of the built-in electric field at the heterojunction interface, thereby reducing the effective carrier concentration of the narrow bandgap two-dimensional channel material layer and realizing a negative photoconductivity effect.
5. The negative photoconductive optoelectronic device based on heterostructure bandgap engineering control according to claim 1, characterized in that, By selecting the wide-bandgap photosensitive material layer and the narrow-bandgap two-dimensional channel material layer with a difference in Fermi level, a band-bending heterojunction with opposite band shifts is formed at their interface, including: When the wide bandgap photosensitive material layer is a p-type semiconductor and the narrow bandgap two-dimensional channel material layer is an n-type semiconductor, the Fermi level of the n-type semiconductor should be lower than that of the p-type semiconductor, and the difference between their Fermi levels should be ≥0.05 eV.
6. The negative photoconductive optoelectronic device based on heterostructure bandgap engineering control according to claim 5, characterized in that, Under illumination, photogenerated holes generated by the p-type semiconductor in the wide bandgap photosensitive material layer are injected into the n-type semiconductor in the narrow bandgap two-dimensional channel material layer under the action of the built-in electric field at the heterojunction interface, thereby reducing the effective carrier concentration of the narrow bandgap two-dimensional channel material layer and realizing a negative photoconductivity effect.
7. The negative photoconductive optoelectronic device based on heterostructure bandgap engineering control according to claim 1, characterized in that, The band gap of the semiconductor in the narrow band gap two-dimensional channel material layer should be between 0.1 eV and 1.0 eV, and the material should be selected from two-dimensional black phosphorus, transition metal chalcogenides, or other narrow band gap two-dimensional semiconductors with comparable band gaps.
8. The negative photoconductive optoelectronic device based on heterostructure bandgap engineering control according to claim 1, characterized in that, The band gap of the semiconductor in the wide bandgap photosensitive material layer should be between 2.0 eV and 6.0 eV, and the material should be selected from gallium oxide, gallium nitride, zinc oxide, cuprous oxide, diamond, or other wide bandgap semiconductors with comparable band gaps.