MgZnO based ultraviolet photodetector with high photoresponsivity achieved by fluorine doping

Publication date: Available online 3 April 2017
Source:Thin Solid Films
Author(s): Yaonan Hou, Zengxia Mei, Zhanglong Liu, Huili Liang, Changzhi Gu, Xiaolong Du
We report a high-responsivity ultraviolet photodetector fabricated from fluorine doped Mg0.4Zn0.6O thin film grown by molecular beam expitaxy. The doped epitaxial film demonstrates a low resistivity with a carrier concentration of 2.18×10¹⁷ cm⁻³ and mobility of 2.67cm²/Vs⁻¹ by Van der Pauw Hall measurements. With a further study of a single Ti/Au-MgZnO:F Schottky junction, it is found the device has a lowered barrier height of 0.59–0.64eV compared with the calculated value. Our photodetector configured with a metal-semiconductor-metal structure with Ti/Au interdigital electrodes exhibits a high photoresonsivity of 80A/W, nearly 800 times larger than that of undoped sample. This record-high value is attributed to the lowered Schottky barrier as well as reduced barrier thickness thanks to the effective fluorine doping.