Thin film transistors and metal–semiconductor–metal photodetectors based on GaN thin films grown by inductively coupled plasma metal-organic chemical vapor deposition

Abstract

Abstract Gallium nitride (GaN) films with an almost single-crystalline quality, smooth surface, and high optical transmission were prepared at 580 °C using inductively coupled plasma metal-organic chemical vapor deposition (ICP-MOCVD) based on a showerhead structure. The GaN thin films with unintentional doping were used as the active layer in the production of thin-film transistors (TFTs) and metal–semiconductor–metal (MSM) photodetectors. TFTs had on-to-off current ratios of 6.3 × 103 and their output characteristics demonstrated the proper saturation behavior of transistors. The field-effect mobility was 3.79 cm2 (V s)−1. MSMs were visible blind, with a contrast of almost three orders of magnitude between ultraviolet and green light. The maximum responsivity was 34 mA W−1 with a 10 V bias voltage and a 325 nm illumination. When the bias voltage was >2 V, the quantum efficiency and noise equivalent power under 266 nm illumination reached >10% and <1 pW ( H z 1/2 ) − 1 , respectively. These findings suggest that the ICP-MOCVD technique has the potential to be used to fabricate (opto)electronic devices at low temperatures.