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【Member Papers】Optoelectronic logic gates and chaotic encryption optical communication enabled by dual-band optical response in a-Ga₂O₃/Cr₂O₃ heterostructures
日期：2026-02-02阅读：24
Researchers from the Chongqing Normal University have published a dissertation titled "Optoelectronic logic gates and chaotic encryption optical communication enabled by dual-band optical response in a-Ga₂O₃/Cr₂O₃ heterostructures " in Materials Today Physics.
Abstract
Self-powered bipolar photodetectors (PDs) have garnered significant attention for their potential in optoelectronic logic gates (OELGs) and secure optical communication systems, owing to their extremely low power consumption and cost-effectiveness. However, conventional unipolar PDs are constrained by functional rigidity and their reliance on passive decoding circuits. In this study, a self-powered bipolar photoelectrochemical detector (PEC-PD) is presented with a wavelength-dependent photoresponse in electrolytes, based on an amorphous gallium oxide/chromium oxide (a-Ga2O3/Cr2O3) p–n heterojunction. This distinctive behavior arises from variations in the competitive dynamics between interfacial redox reactions and photogenerated carrier transport at the semiconductor/electrolyte interface under short-wave ultraviolet (UV-C) and long-wave ultraviolet (UV-A) irradiation. The device exhibits a positive photocurrent response time of 82.1/91.2 ms under 254 nm illumination and a negative photocurrent response time of 9.1/13.6 ms under 380 nm without an external power supply. Utilizing this tunable photoresponse, five fundamental Boolean logic operations—“OR”, “AND”, “NOR”, “NOT”, and “NAND”—are demonstrated by tailoring the illumination at specific wavelengths. Furthermore, the distinct bipolar photocurrent behaviors enable encrypted optical communication within a single photoelectrode architecture. This study advances the understanding of carrier dynamics manipulation and provides a solid foundation for the development of multi-functional OELGs and secure optical communication systems.
Figure 1. a) Schematic fabrication process of Cr2O3 thin film. b) Heterostructure design of the a-Ga2O3/Cr2O3 junction. c) Cross-sectional SEM image of a-Ga2O3/Cr2O3. d) Surface EDS elemental mapping of a-Ga2O3/Cr2O3. e-g) M–S analysis of a-Ga2O3, Cr2O3 and a-Ga2O3/Cr2O3, respectively. h) Raman scattering spectrum of a-Ga2O3/Cr2O3. i) Ga 2p3/2 XPS spectra of pristine a-Ga2O3 and a-Ga2O3/Cr2O3, showing peak positions at 1118.47 and 1118.50 eV, respectively. j) Cr 2p3/2 XPS spectra of pristine Cr2O3 and a-Ga2O3/Cr2O3, showing peak positions at 576.36 and 576.27 eV, respectively.
Figure 2. a) I-t characteristics of the a-Ga2O3/Cr2O3 PEC detector under various wavelengths at 0 V bias (500 μW cm−2). b) I-t response of the a-Ga2O3/Cr2O3 PEC detector at 0 V bias under 254 and 380 nm illumination with varying light intensities. c, d) Extracted photocurrent density and responsivity versus light intensity at 254 and 380 nm. e) Response time characteristics at 0 V bias under 254 and 380 nm illumination. f) Comparison of response times with reported PDs. g) Long-term stability test over 3000 s at 0 V under 254 and 380 nm illumination. h) Magnified view of stability performance during 1500–1600 s.
Figure 3. a) Absorption spectrum and optical band gap of a-Ga2O3. b) Absorption spectrum and optical band gap of Cr2O3. c) Valence-band XPS spectra and Ga 2p core level spectrum of a-Ga2O3. d) Valence-band XPS spectra and Cr 2p core level spectrum of Cr2O3. e) Ga 2p and Cr 2p core level spectra of a-Ga2O3/Cr2O3 heterojunction. f) Band alignment diagram of a-Ga2O3/Cr2O3 heterojunction. g) Plane averaged electronic potential of a-Ga2O3 and Cr2O3. The inserts show atomic models of two structures. h) Operational mechanism of a-Ga2O3/Cr2O3 under 254 nm illumination. i) Operational mechanism of a-Ga2O3/Cr2O3 under 380 nm illumination.
Figure 4. Schematic diagrams of five OELGs implemented using a single self-powered PEC-PD: a) “OR” and “AND” gates using two UV-C inputs under UV-A gate modulations. b) “NOR”, “NOT”, and “NAND” gates using two UV-A inputs under UV-C gate modulations. c) Truth table for five OELGs under four input combinations. d-g) OELGs operations. d) Photocurrent output versus UV-A intensity for UV-C inputs. e) Transient photocurrent curves of “OR” and “AND” gates under UV-C inputs (100 μW cm−2) at UV-A intensities of 8, 84, and 256 μW cm−2, respectively. f) Photocurrent output versus UV-C intensity for UV-A inputs. g) Transient photocurrent curves of “NOT”, “NOR”, and “NAND” gates under UV-A inputs (45 μW cm−2) at UV-C intensities of 120, 150, and 340 μW cm−2 respectively.
Figure 5. a) Schematic of the dual-channel optical communication test setup and detailed encapsulation of the working electrode. b) Matrix obtained after chaotic encryption and XOR processing of the encoded binary matrix. c) Encrypted matrix obtained after chaotic encryption and XOR processing of the binary-encoded matrix. d) Normalized photocurrent response of the a‑Ga2O3/Cr2O3 photoelectrode under four optical switching states using 254 and 380 nm illumination, demonstrating a direct correspondence to DNA base sequences. e) Conventional unidirectional photoelectrode receiving intercepted DNA-encoded signal: decoded image with missing information. f) Decrypted image matching the original input, achieved using the correct chaotic key and DNA-encoded signals received by the a‑Ga2O3/Cr2O3 photoelectrode. g) Bipolar photoelectrode receiving intercepted DNA-encoded signal with erroneous chaotic key: decoded image deviating significantly from the original input.
Quancai Yue, Lijuan Ye, Lai Yuan, Guoping Qin, Di Pang, Yan Tang, Honglin Li*, Hong Zhang* and Wanjun Li*. Optoelectronic Logic Gates and Chaotic Encryption Optical Communication Enabled by Dual-Band Optical Response in a-Ga2O3/Cr2O3 Heterostructures. Materials Today Physics, 2026, 61: 102032.
DOI：
https://doi.org/10.1016/j.mtphys.2026.102032.
