Self-powered α-Ga₂O₃/CdS quantum-dot photodetector unlocks broadband response and programmable logic gates via pyro-phototronic effect
image: The low-cost, compact α-Ga₂O₃ nanorod arrays (NRAs)/CdS quantum dots (QDs) PEC detector can perform AND, OR, and NOT logic operations by modulating the bias voltage, light intensity, and light wavelength, and can be used for information transmission.
Credit: Nano Research, Tsinghua University Press
Next-generation photodetectors must simultaneously deliver broadband spectral coverage, high sensitivity and self-powered operation if they are to support everything from ubiquitous information exchange to round-the-clock health monitoring. A low-cost n–n heterojunction that replaces the traditional p–n architecture has produced a photoelectrochemical (PEC) photodetector that operates across 220–700 nm without external bias, delivers record-short 30 ms/24 ms response times for Ga₂O₃-based systems, and performs reconfigurable Programmable logic in real time. The work, led by Professor Shujie Jiao at the School of Materials Science and Engineering, Harbin Institute of Technology, appears in the 20 October issue of Nano Research.
“Conventional Ga₂O₃ detectors are blind to visible light and need seconds to reset,” says Jiao, corresponding author. “Decorating α-Ga₂O₃ nanorods with CdS quantum dots extends the window to the full UV–visible range while cutting the response to milliseconds—entirely self-powered.”
Fabrication is wafer-scale and solution-based: vertical α-Ga₂O₃ nanorods are grown hydrothermally on FTO glass, coated with CdS via chemical-bath deposition, and annealed at 350 °C in argon. Under 254 nm illumination the heterojunction yields 1.54 µA cm⁻², 169 % higher than bare Ga₂O₃; at 450 nm it reaches 2.99 µA cm⁻²—effectively zero for Ga₂O₃ alone. Pyro-phototronic amplification peaks at 191 %, pushing specific detectivity beyond 8.47 × 10⁹ Jones and reducing rise/fall times to 30 ms and 24 ms, the fastest yet reported for Ga₂O₃ PEC detectors.
The boost originates from the spontaneous polarization of CdS along its c-axis. Light-induced heating transiently reduces polarization, generating a pyroelectric field that reinforces the built-in field and accelerates carrier separation; cooling upon light-off reverses the process, producing a sharp opposite current. This bidirectional signature is exploited for logic: 254 nm and 450 nm LEDs serve as dual optical inputs, and photocurrent thresholds define output levels, enabling “AND”, “OR” and “NOT” gates in a single pixel. The device successfully decodes the ASCII message “HIT” in real time—the first complete optical-communication demonstration on a PEC platform.
Jiao envisions embedding the detector in wearable or metaverse sensing nodes “to integrate health monitoring, on-sensor preprocessing and wireless optical communication in one unit”.
The National Natural Science Foundation of China (62174042) and the National Key R&D Program of China (2019YFA0705201) supported the work. All data and supplementary figures are available in the online version of the paper.
About the Authors：
Dr. Shujie Jiao is a full professor in the Faculty of School of Materials Science and Engineering, Harbin Institute of Technology, China. Her research interests focus on the wide band gap semiconductor and photodetector such as Ga2O3 photodetector. Until now, she has published more than 100 papers in Advanced Materials and other journals, presided over 20 national/provincial scientific research projects, owns 14 invention patents. For more information, please pay attention to her research homepage https://homepage.hit.edu.cn/shujiejiao?lang=zh
About Nano Research
Nano Research is a peer-reviewed, open access, international and interdisciplinary research journal, sponsored by Tsinghua University and the Chinese Chemical Society, published by Tsinghua University Press on the platform SciOpen. It publishes original high-quality research and significant review articles on all aspects of nanoscience and nanotechnology, ranging from basic aspects of the science of nanoscale materials to practical applications of such materials. After 18 years of development, it has become one of the most influential academic journals in the nano field. Nano Research has published more than 1,000 papers every year from 2022, with its cumulative count surpassing 7,000 articles. In 2024 InCites Journal Citation Reports, its 2024 IF is 9.0 (8.7, 5 years), and it continues to be the Q1 area among the four subject classifications. Nano Research Award, established by Nano Research together with TUP and Springer Nature in 2013, and Nano Research Young Innovators (NR45) Awards, established by Nano Research in 2018, have become international academic awards with global influence.