Enhanced Zero-Bias UV Detection via Pyroelectric-Photovoltaic Coupling in Single-Crystal Ga:ZnO-Based Photodetectors

In this work, a high-performance photoelectrochemical (PEC) ultraviolet photodetector based on a high-quality conductive bulk Ga:ZnO (GZO) single crystal is demonstrated, where the synergistic coupling of pyroelectric and photovoltaic effects significantly enhances carrier separation and collection efficiency at the semiconductor/electrolyte interface. Under zero bias and 257 nm illumination (0.15 mW/cm²), the device achieves high performance metrics, including a high UV-visible rejection ratio of 2.2×10³, a high photoresponsivity of 24.4 mA/W, a fast decay time of 33 ms, and a specific detectivity of 6×10¹⁰ Jones. Notably, the synergistic interaction between light-induced pyroelectric polarization and interfacial photovoltaic potential results in a 340% increase in the maximum transient photoresponsivity of the device over the steady state response under 257 nm irradiation with 11.9 mW/cm². Benefiting from the low defect density and superior thermal stability of bulk GZO single crystals, the photodetector maintains reliable operation across a broad temperature range (30–75 ℃). Furthermore, the device successfully receives and transmits Morse code-encoded optical signals, demonstrating its significant potential in secure optical communication applications.