Improved detection performance of self-driven InZnO / p-GaN heterojunction UV photodetector by lanthanum doping

By using the sol-gel spin-coating method, La-InZnO films with different La (0 at%, 2 at%, 4 at%, and 6 at%) doping concentrations were grown on p-GaN / sapphire film templates, and self-driven p-GaN / n-ZnO heterojunction ultraviolet (UV) detectors were prepared. The effects of La doping concentration on the microstructure, optical, and electrical properties of synthesized La-InZnO films were studied. In addition, the optical sensing characteristics and photoelectric response performance of four p-n heterojunction UV detectors were compared. La doping can decrease the content of oxygen vacancies. It also reduces the carrier concentration and mobility of the films. At zero bias voltage, the 2 at% doped device has the best performance, with a peak responsivity of 46 mA/W at 366 nm, a high spectral selectivity full width at half maximum (FWHM) of only 6.92 nm, and a fast response with the rise and decay times of 1.15 ms and 2.42 ms, respectively. This study demonstrates a feasible method for improving the performance of self-driven heterojunction UV detectors.