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

Abstract

Abstract In this work, a solar-blind ultraviolet (UV) photodetector based on a three-terminal enhancement-mode (E-mode) Si-doped β -Ga 2 O 3 ( β -Ga 2 O 3 :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 β -Ga 2 O 3 :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 × 10 4 and linear dynamic range of 29.6 dB, illuminated by 254 nm UV light of 245 μ W cm −2 . As the UV light is turned on and off, the output current rise and decay time ( τ r and τ 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 <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mo>×</mml:mo> </mml:math> 10 14 cm Hz 1/2 W −1 (Jones) and 3.6 <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mo>×</mml:mo> </mml:math> 10 4 %, respectively.