Observation of ultraviolet photothermoelectric bipolar impulse in gallium-based heterostructure nanowires
Jinjie Zhu, Qing Cai, Pengfei Shao, Shengjie Zhang, Haifan You, Hui Guo, Jin Wang, Junjun Xue, Bin Liu, Hai Lu, Youdou Zheng, Rong Zhang, Dunjun Chen
Abstract
The incorporation of thermal dynamics alongside conventional optoelectronic principles holds immense promise for advancing technology. Here, we introduce a GaON/GaN heterostructure-nanowire ultraviolet electrochemical cell of observing a photothermoelectric bipolar impulse characteristic. By leveraging the distinct thermoelectric properties of GaON/GaN, rapid generation of hot carriers establishes bidirectional instantaneous gradients in concentration and temperature within the nanoscale heterostructure via light on/off modulation. The thermoelectromotive force induced by these gradients, combined with the type-II heterojunction band structure, facilitates carrier transport, resulting in transient bidirectional photothermal currents. The device achieves exceptional responsivity (17.1 mA/W) and remarkably fast speed (8.8 ms) at 0 V, surpassing existing semiconductor electrochemical cells. This bipolar ultraviolet impulse detection mode harnesses light-induced heat for electricity generation, enabling innovative bidirectional encryption communication capabilities. Anticipated applications encompass future sensing, switchable light imaging, and energy conversion systems, thereby laying a foundation for diverse optoelectronic technological advancements.