Ultrasonic Assisted Mist Chemical Vapor Deposition Deposited MgO for AlGaNGaN Metal-Insulator-Semiconductor Ultraviolet Photodetector

Abstract

This work uses an ultrasonic assisted mist chemical vapor deposition (UAM-CVD) technique to deposit the MgO film of 10nm as the insulator layer of the AlGaNGaN metal-insulator-semiconductor (MIS) ultraviolet photodetector. The illumination area was designed to be 0.47 mm2. The thickness of the MgO film is confirmed by transmission electron microscopy (TEM). The optical characteristics of the MgO film like refractive index, extinction coefficient, and optical transmittance are characterized by the ellipsometer and the UVVISIR spectrometer. The dark current of the MIS photodetector is 5.03pA, which is much lower than the Schottky barrier photodetector of 4.23nA. The MIS photodetector shows higher internal photoconductive gain compared to the Schottky barrier photodetector. Therefore, the MIS photodetector has high photoresponsivity of 0.44AW (360nm). Such high responsivity gives the MIS photodetector a low noise equivalent power of 3.83 1012 W (360 nm) and high detectivity of $1.79\times 10^{10}$ Jones (360 nm).