Enhancement-mode normally-off β-Ga2O3:Si metal-semiconductor field-effect deep-ultraviolet phototransistor

In this work, a solar-blind ultraviolet (UV) photodetector based on a three-terminal enhancement-mode (E-mode) Si-doped beta-Ga2O3 (beta-Ga2O3:Si) metal-semiconductor field-effect transistor structure is demonstrated, whose threshold voltage (V-th) and subthreshold swing are 4.04 V and 1.4 V dec(-1), respectively. A 400 nm thick beta-Ga2O3:Si thin film is prepared on sapphire substrate by using metal-organic chemical vapor deposition method. Controlling the channel currents by the Schottky gate voltage in the dark and under illuminations, the photodetector shows dark current (I-dark) as low as 13.4 pA, photo-to-dark current ratio of 4.85 x 10(4) and linear dynamic range of 29.6 dB, illuminated by 254 nm UV light of 245 mu W cm(-2). As the UV light is turned on and off, the output current rise and decay time (tau(r) and tau(d)) are 420 ms and 350 ms. Moreover, at drain voltage (V-ds) of 5 V and gate voltage (V-gs) of 0 V, the responsivity (R), specific detectivity (D*) and external quantum efficiency are achieved as 74 A W-1, 2.15 x 10(14) cm Hz(1/2) W-1 (Jones) and 3.6 x 10(4) %, respectively.

Automated summary

In this work, a solar-blind ultraviolet photodetector based on an Si-doped beta-Ga2O3 metal-semiconductor field-effect transistor structure is demonstrated. The photodetector exhibits low dark current, high linear dynamic range, and a good ratio of photo-to-dark current.