A Scanning Imaging Encryption Transmission Method Based on GaN Heterojunction Devices

Abstract

This invention discloses a scanning imaging encrypted transmission method based on GaN heterojunction devices, belonging to the field of semiconductor optoelectronics technology. The method achieves encryption by switching the same device between a high-speed "probe mode" and a "synaptic mode" with a memory effect, utilizing the response differences between the two operating modes. Because its encryption key is an analog and time-varying bias protocol rather than a simple digital sequence, this "physically unclonable function" characteristic endows it with extremely high encryption strength, making it difficult to crack by conventional algorithms and providing higher security.

Description

Technical Field

[0001] This invention relates to a scanning imaging encryption transmission method based on GaN heterojunction devices, belonging to the field of semiconductor optoelectronic technology. Background Technology

[0002] With the rapid development of information technology and artificial intelligence, the demand for high-performance, highly integrated, and multifunctional intelligent devices is increasing. Ultraviolet photodetectors based on wide-bandgap semiconductors (such as gallium nitride, GaN) have attracted much attention due to their enormous potential in fields such as flame detection, secure communication, and biomedicine. However, traditional detectors are typically single-function, limited to converting optical signals into electrical signals. Information processing and encryption functions rely on independent back-end circuits and complex software algorithms, resulting in high overall system power consumption, large latency, and vulnerability to algorithmic breaches.

[0003] On the other hand, inspired by the efficient information processing capabilities of the biological brain, neuromorphic computing has become a research hotspot. Among these advancements, photoelectric synaptic devices, capable of mimicking the plasticity of biological synapses, offer the possibility of constructing low-power, highly parallel intelligent sensing systems. Utilizing the persistent photoconductivity (PPC) effect of materials is one effective way to realize photoelectric synaptic functions. The PPC effect allows the device to maintain a high conductivity state for a period of time after the light is removed, simulating biological synaptic "memory." However, the slow response characteristics of the PPC effect contradict the requirements of traditional high-speed photoelectric detection. How to achieve both functions in a single device and switch between them on demand presents a significant challenge.

[0004] Furthermore, information security is central to modern communication and imaging systems. Existing encryption technologies are primarily based on software algorithms, which, while mature, consume significant computational resources and are vulnerable to brute-force attacks. Hardware encryption, by binding keys to the physical characteristics of devices, offers enhanced security. However, existing hardware encryption schemes are typically complex in structure or have limited functionality. Summary of the Invention

[0005] To address the existing problems, this invention, based on the previously filed invention patent for a self-driven solar-blind ultraviolet detector based on an asymmetric Schottky barrier (publication number CN 117673188 A), expands the functionality of the developed high-performance group III nitride heterojunction device platform, discovering a completely new operating mode for the device: by dynamically adjusting the bias voltage, the same device can switch between a high-speed "detection mode" and a "synaptic mode" with a memory effect. Based on this bimodal property, an encrypted transmission method for point scanning imaging is provided, which is more secure than existing methods that require additional back-end circuitry and hardware / software encryption algorithms for transmission, and does not require additional back-end circuitry.

[0006] The first object of the present invention is to provide a multifunctional optoelectronic device with both high-speed optoelectronic detection function and optoelectronic synaptic function. The multifunctional optoelectronic device includes a substrate, a GaN buffer layer / channel layer, a barrier layer, a ring-shaped ohmic electrode and a circular Schottky electrode from bottom to top. The barrier layer is an aluminum-containing group III nitride layer, and the aluminum-containing group III nitride layer is a thin film material with at least one layer structure. Each layer of material is Al x Ga 1-x N(0 < x ≤ 1), Al y Sc 1- y N(0 < y < 1), Al x In 1-x N(0 < x < 1), or any combination thereof. The aluminum-containing group III nitride layer and the underlying GaN buffer layer / channel layer together form a heterojunction. By applying different bias voltages to the multifunctional optoelectronic device, it can work in the optoelectronic detection mode or the optoelectronic synaptic mode.

[0007] Optionally, the first interval bias voltage corresponding to the optoelectronic detection mode is greater than 0V and less than 5V, and the second interval bias voltage corresponding to the optoelectronic synaptic mode is greater than 5V and less than 20V.

[0008] Optionally, the ring-shaped ohmic electrode is prepared by Ti / Al / Ni / Au, and the ring-shaped ohmic electrode forms an ohmic contact with the GaN buffer layer / channel layer; the Schottky electrode is prepared by Ni / Au, and the Schottky electrode forms a Schottky barrier with the barrier layer.

[0009] The second object of the present invention is to provide a dot-scanning imaging encryption transmission method based on a GaN heterojunction device. The method is implemented based on the above-mentioned multifunctional optoelectronic device, and the method includes:

[0010] Converting the light intensity information obtained by point-by-point scanning of the target image into an optical signal sequence P(t);

[0011] Designing a time-varying dynamic bias protocol V(t) as an encryption key, and the V(t) switches between the bias voltages in the first interval and the second interval; M

[0012] Synchronously applying the optical signal sequence P(t) and the dynamic bias protocol V(t) to the multifunctional optoelectronic device, and using the response difference of the multifunctional optoelectronic device in two working modes, an encrypted current signal I(t) is obtained for transmission.

[0013] Optionally, the method further includes decrypting the output current signal I(t):

[0014] Based on the decryption key consistent with the dynamic bias protocol V(t) used during encryption, an inverse algorithm is performed on the encrypted current signal I(t) to separate the signal components generated by the multifunctional optoelectronic device's response in different modes, thereby reconstructing the original light intensity information.

[0015] Optionally, the method further includes:

[0016] The target image is scanned point by point using a two-dimensional moving platform. Ultraviolet light of a specific wavelength is emitted by xenon and irradiated onto the device surface. An electrically driven XY displacement stage, with a mask corresponding to the image, is added to the optical path. By continuously moving the mask, the device output receives current data that changes over time. This current data is input into Matlab software, and the resulting image is the cutout image of the mask.

[0017] Optionally, the bias voltage of the first interval is greater than 0V and less than 5V; the bias voltage of the second interval is greater than 5V and less than 20V.

[0018] The third objective of this invention is to provide a scanning imaging encrypted transmission system based on GaN heterojunction devices, including the aforementioned multifunctional optoelectronic devices, optical modules, signal generators, synchronization control units, current measurement modules, and data processing units.

[0019] The multifunctional optoelectronic device is used to encrypt the optical signal sequence. The optical module is used to convert the raw optical information obtained by scanning imaging into an optical signal sequence P(t). The signal generator is used to generate a dynamic bias protocol V(t) as the encryption key, which switches between two interval bias voltages of the multifunctional optoelectronic device. The synchronization control unit is used to ensure that the input optical signal sequence P(t) and the dynamic bias protocol V(t) are synchronously applied to the multifunctional optoelectronic device. The current measurement module is used to acquire the encrypted current signal I(t) generated by the multifunctional optoelectronic device. The data processing unit is used to store and process the encrypted signal, or to perform decryption operations when a decryption key is available.

[0020] Optionally, the system further includes a two-dimensional scanning platform for carrying the multifunctional optoelectronic device or the object to be imaged, to achieve point-by-point scanning imaging.

[0021] Optionally, the two-dimensional scanning platform is an electric XY displacement stage.

[0022] The beneficial effects of this invention are:

[0023] First, this invention achieves deep integration of four functions—photoelectric detection, neuromorphic computing, scanning imaging, and encryption—on a single two-terminal device, significantly improving the device's integration and functional density. Second, regarding security, the encryption process relies heavily on the device's unique bias-controlled physical characteristics. Its key is an analog, time-varying bias protocol rather than a simple digital sequence. This "physically unclonable function" characteristic endows it with extremely high encryption strength, making it difficult to crack using conventional algorithms. Furthermore, based on this external bias control mechanism, the device's functions can be flexibly reconfigured, allowing it to seamlessly adapt to different application scenarios, sometimes functioning as a high-speed imaging sensor, sometimes as a neuromorphic computing unit, exhibiting excellent pattern reconfigurability. Finally, from a structural perspective, this invention employs a simple two-terminal device structure. Compared to traditional three-terminal transistor devices, its fabrication process is simpler, and its integration potential is greater, laying a solid foundation for future large-scale applications. Attached Figure Description

[0024] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying 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.

[0025] Figure 1 This is a schematic diagram of the heterojunction device used in the embodiments of the present invention.

[0026] Figure 2 This is a graph showing the photoconductivity response of the heterojunction device used in this invention under different bias voltages.

[0027] Figure 3 This is a schematic diagram of the experimental results of simulating biological synaptic functions (such as PPF and STM to LTM transition) of the heterojunction device under high bias.

[0028] Figure 4 This is a schematic diagram of a system device for scanning optical imaging in an embodiment of the present invention.

[0029] Figure 5 This is a flowchart illustrating the hardware encryption imaging scheme based on the dynamic bias protocol proposed in this invention.

[0030] Figure 6 This is a schematic diagram of the time-domain waveform of a key signal during the encryption process.

[0031] Figure 7 This is a schematic diagram of a scanning imaging encrypted transmission system based on GaN heterojunction devices. Detailed Implementation

[0032] To make the objectives, technical solutions and advantages of the present invention more clear, the embodiments of the present invention will be further described in detail below with reference to the accompanying drawings.

[0033] Embodiment 1

[0034] This embodiment provides a multifunctional optoelectronic device with both high-speed photoelectric detection function and optoelectronic synaptic function. Referring to Figure 1 , the multifunctional optoelectronic device sequentially includes a substrate, a GaN buffer layer / channel layer, a barrier layer, a ring-shaped ohmic electrode and a circular Schottky electrode from bottom to top. The barrier layer is an aluminum-containing group III nitride layer, and the aluminum-containing group III nitride layer is a thin film material including at least one layer structure. Each layer of material is Al x Ga 1-x N(0 < x ≤ 1), Al y Sc 1-y N(0 < y < 1), Al x In 1-x N(0 < x < 1) or any combination thereof. The aluminum-containing group III nitride layer and the underlying GaN buffer layer / channel layer together form a heterojunction. By applying bias voltages in different ranges to the multifunctional optoelectronic device, it can work in the photoelectric detection mode or the optoelectronic synaptic mode.

[0035] Apply a bias voltage lower than 5V to the multifunctional optoelectronic device to make it work in the photoelectric detection mode. In this mode, the internal electric field in the device is weak, enabling the photo-generated carriers to recombine quickly. Therefore, the device exhibits fast transient response characteristics, and its photocurrent can accurately follow the dynamic changes of the input optical signal, showing typical high-speed and high-sensitivity photodetector behavior. This mode is particularly suitable for application fields that require real-time signal response, such as high-speed scanning imaging and optical communication.

[0036] Apply a bias voltage higher than 5V to the multifunctional optoelectronic device. In this mode, the significantly enhanced internal electric field can efficiently separate the photo-generated electron-hole pairs, and effectively capture one of the carriers (such as holes) at the heterojunction interface or in the deep-level defect states inside the material. These captured charges form a persistent built-in electric potential, which has a modulation effect on the channel conductance similar to the optically controlled gate voltage, enabling the conductivity of the device to remain at a relatively high level for a long time even after the light illumination is removed, thereby generating a significant PPC effect. The characteristic of the slow decay of the photocurrent highly simulates the memory function of biological synapses. Therefore, it can be used to achieve synaptic plasticity in neuromorphic computing, such as simulating synaptic plasticity behaviors including excitatory postsynaptic current (EPSC), paired-pulse facilitation (PPF), and the transition from short-term memory (STM) to long-term memory (LTM) by regulating the intensity, pulse width, pulse interval or pulse number of the input optical signal.

[0037] like Figure 2 As shown, when operating in the low-bias region with a low bias voltage (less than 5V), the internal electric field of the device is insufficient to effectively prevent the rapid recombination of photogenerated carriers. Therefore, after illumination stops, its photoconductivity decays rapidly, exhibiting a typical fast detection mode. Conversely, when the bias voltage is increased to the high-bias region (greater than 5V, especially significant at 15V and 20V), the strong electric field inside the device can efficiently separate photogenerated carriers and trap carriers such as holes in deep-level defect states, forming a persistent "grating voltage" to continuously modulate the channel conductance. This leads to a strong PPC effect, meaning that the photocurrent can remain at a high level for a long time after illumination stops and decays slowly, causing the device to enter a slow memory mode.

[0038] In high-bias (15V) memory mode, this device can be used as a photo-controlled artificial synapse. For example... Figure 3 As shown, various biological synaptic plasticities can be simulated by designing different light pulse inputs (presynaptic stimulation). For example, applying two light pulses with a very short time interval results in a higher current response (postsynaptic current) induced by the second pulse compared to the first, successfully simulating PPF, a form of short-term memory. By increasing the intensity, duration, or frequency of the light pulses (repetitive stimulation), the sustained photocurrent level of the device can be significantly increased and decayed more slowly, simulating the consolidation process from STM to LTM.

[0039] In a low-bias (1V) fast detection mode, the device can be used as a high-performance pixel unit for ultraviolet scanning imaging. For example... Figure 4 The system shown places a photomask engraved with the "JNU" pattern on the device and performs two-dimensional raster scanning using a motorized XY stage. The photocurrent value of the device is recorded at each pixel. Due to the device's fast response speed, high frame rate scanning can be achieved. After acquiring the current data from all pixels, a clear image of "JNU" can be reconstructed in the computer.

[0040] Example 2

[0041] This embodiment provides a scanning imaging encrypted transmission method based on GaN heterojunction devices, implemented using a multifunctional optoelectronic device with both high-speed photoelectric detection and photoelectric synaptic functions as provided in Embodiment 1, including:

[0042] The raw optical information obtained from point scanning imaging is converted into an optical signal sequence P(t);

[0043] Design a time-varying dynamic bias protocol V(t) as the encryption key. V(t) switches between bias voltages in a first interval and a second interval over time. The bias voltage in the first interval is greater than 0V and less than 5V, and the bias voltage in the second interval is greater than 5V and less than 20V.

[0044] The optical signal sequence P(t) and the dynamic bias protocol V(t) are synchronously applied to the multifunctional optoelectronic device provided in Embodiment 1. By utilizing the response difference of the multifunctional optoelectronic device in the two working modes, an encrypted current signal I(t) is obtained for transmission.

[0045] At the decryption end, based on the decryption key consistent with the dynamic bias protocol V(t) used during encryption, the reverse algorithm is performed on the encrypted current signal I(t) to separate the signal components generated by the multifunctional optoelectronic device's response in different modes, thereby reconstructing the original optical information.

[0046] The encryption principle described above is as follows: When the encryption key V(t) is at a low voltage value, the device operates in fast detection mode, and the output current I(t) mainly reflects the intensity of the current optical signal P(t). However, when the key V(t) jumps to a high voltage value, the device switches to memory mode. At this time, the output current is not only related to the current P(t), but also affected by the previous illumination history accumulated by the PPC effect. Therefore, the final output current I(t) is no longer a simple linear mapping of the input optical signal, but a nonlinear convolution between the input optical signal P(t) and the time-varying physical state inside the device controlled by the key V(t), thus achieving intrinsic encryption of information at the hardware level.

[0047] For example, such as Figure 5 As shown, at the encryption end, this method first scans the original information to be encrypted (an image of a handwritten digit "5") pixel by pixel, converting its grayscale values ​​into a series of light pulses with specific intensity or width, thus forming a time-series input light signal P(t). Simultaneously, a dynamic bias protocol V(t) strictly synchronized with the scanning sequence of P(t) is preset as the physical encryption key. For example... Figure 6 As shown, the waveform of the key V(t) dynamically switches between low voltage (1V) and high voltage (15V) according to a predetermined rule. The predetermined rule is the rule of voltage switching time, which can be freely set.

[0048] The key step in encryption is to synchronously apply the optical signal P(t) and the bias key V(t) to the device. At this point, the device's response becomes complex: when V(t) is at a low voltage, the device operates in fast detection mode, and its output current is essentially proportional to the light intensity of the current pixel; while when V(t) jumps to a high voltage, the device switches to memory mode, and its output current not only reflects the light intensity of the current pixel but also includes the "memory" of previous illumination history accumulated by the PPC effect. This memory also affects the current baseline under subsequent low bias conditions.

[0049] Therefore, the final acquired output current I(t) is a string of encrypted data encrypted by a hardware physical process. If it is directly used for image reconstruction, a completely distorted and unrecognizable pattern will be obtained.

[0050] Accordingly, at the decryption end, the authorized receiver must meet two prerequisites: first, possess a heterojunction device whose characteristics perfectly match those of the encryption end; second, possess the bias key V(t) and its synchronization timing that are completely consistent with the encryption process. During decryption, the receiver inputs the received optical signal P(t) into the system and uses a signal generator to accurately reproduce the key V(t), applying both to its own device in strict synchronization. Through this operation, the physical state changes of the receiver's device will completely reproduce the encryption process. Subsequently, by processing the measured current through a pre-set inverse algorithm based on the device response model, the original light intensity of each pixel can be accurately recovered, ultimately reconstructing a clear original image "5". This mechanism ensures that any third party that does not possess the correct bias key V(t), even if it intercepts the optical signal P(t), cannot correctly drive the device to reproduce its physical response, thus failing to decode valid information, greatly guaranteeing the inherent security of information transmission.

[0051] Example 3

[0052] This embodiment provides a scanning imaging encrypted transmission system based on GaN heterojunction devices, including a multifunctional optoelectronic device with both high-speed photoelectric detection and photoelectric synapse functions, an optical module, a signal generator, a synchronization control unit, a current measurement module, and a data processing unit, as provided in Embodiment 1. Figure 7 As shown.

[0053] The multifunctional optoelectronic device encrypts optical signal sequences based on its two operating models. The optical module converts the raw optical information obtained from point scanning imaging into an optical signal sequence P(t). The signal generator generates a dynamic bias protocol V(t) as the encryption key. V(t) switches between two interval bias voltages of the multifunctional optoelectronic device to achieve encryption. The synchronization control unit ensures that the input optical signal sequence P(t) and the dynamic bias protocol V(t) are applied synchronously to the multifunctional optoelectronic device. The current measurement module acquires the encrypted current signal I(t) generated by the multifunctional optoelectronic device. The data processing unit stores and processes the encrypted signal, or performs decryption operations when the decryption key is available.

[0054] The system also includes a two-dimensional scanning platform for supporting the multifunctional optoelectronic device or the object to be imaged, enabling point-by-point scanning imaging. For example, an electric XY stage can be used to support the multifunctional optoelectronic device or the object to be imaged.

[0055] Some steps in the embodiments of the present invention can be implemented using software, and the corresponding software program can be stored in a readable storage medium, such as an optical disc or a hard disk.

[0056] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A multifunctional optoelectronic device that combines photoelectric detection and photoelectric synaptic functions, characterized in that, The multifunctional optoelectronic device sequentially includes a substrate, a GaN buffer layer / channel layer, a barrier layer, an annular ohmic electrode, and a circular Schottky electrode from bottom to top. The barrier layer is a group-III nitride layer containing an aluminum component. The group-III nitride layer containing an aluminum component is a thin film material with at least one layer structure, and each layer of material is Al x Ga 1-x N(0 < x ≤ 1), Al y Sc 1-y N(0 < y < 1), Al x In 1-x N(0 < x < 1), any one of them or a combination thereof. The group-III nitride layer containing an aluminum component and the underlying GaN buffer layer / channel layer together form a heterojunction. By applying bias voltages in different intervals to the multifunctional optoelectronic device, it can operate in the photodetector mode or the photoelectric synaptic mode.

2. The multifunctional optoelectronic device according to claim 1, characterized in that, The bias voltage of the first interval corresponding to the photoelectric detection mode is greater than 0V and less than 5V, and the bias voltage of the second interval corresponding to the photoelectric synapse mode is greater than 5V and less than 20V.

3. The multifunctional optoelectronic device according to claim 1, characterized in that, The annular ohmic electrode is fabricated using Ti / Al / Ni / Au, and forms an ohmic contact with the GaN buffer layer / channel layer.

4. The multifunctional optoelectronic device according to claim 1, characterized in that, The Schottky electrode is fabricated using Ni / Au, and the Schottky electrode forms a Schottky barrier with the barrier layer.

5. A method for encrypted transmission of scanned imaging based on GaN heterojunction devices, characterized in that, The method is implemented based on the multifunctional optoelectronic device according to any one of claims 1-4, and the method includes: The light intensity information obtained by scanning the target image point by point is converted into a light signal sequence P(t); Design a time-varying dynamic bias protocol V(t) as the encryption key, wherein V(t) switches between bias voltages in the first interval and the second interval; The optical signal sequence P(t) and the dynamic bias protocol V(t) are synchronously applied to the multifunctional optoelectronic device. By utilizing the response difference of the multifunctional optoelectronic device in the two working modes, an encrypted current signal I(t) is obtained for transmission.

6. The method according to claim 5, characterized in that, The method also includes decrypting the output current signal I(t): Based on the decryption key consistent with the dynamic bias protocol V(t) used during encryption, an inverse algorithm is performed on the encrypted current signal I(t) to separate the signal components generated by the multifunctional optoelectronic device's response in different modes, thereby reconstructing the original light intensity information.

7. The method according to claim 6, characterized in that, The bias voltage in the first interval is greater than 0V and less than 5V; the bias voltage in the second interval is greater than 5V and less than 20V.

8. A scanning imaging encrypted transmission system based on GaN heterojunction devices, characterized in that, Includes the multifunctional optoelectronic device, optical module, signal generator, synchronization control unit, current measurement module, and data processing unit as described in any one of claims 1-4; The multifunctional optoelectronic device is used to encrypt the optical signal sequence; the optical module is used to convert the raw optical information obtained by scanning imaging into an optical signal sequence P(t); the signal generator is used to generate a dynamic bias protocol V(t) as an encryption key, which switches between two interval bias voltages of the multifunctional optoelectronic device; the synchronization control unit is used to ensure that the input optical signal sequence P(t) and the dynamic bias protocol V(t) are synchronously applied to the multifunctional optoelectronic device. The current measurement module is used to acquire the encrypted current signal I(t) generated by the multifunctional optoelectronic device; the data processing unit is used to store and process the encrypted signal, or to perform decryption operation when a decryption key is available.

9. The system according to claim 8, characterized in that, The system also includes a two-dimensional scanning platform for carrying the multifunctional optoelectronic device or the object to be imaged, enabling point-by-point scanning imaging.

10. The system according to claim 9, characterized in that, The two-dimensional scanning platform is an electric XY displacement stage.

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