Properties of Ga–Zn–O Ultraviolet Phototransistors Using Radio-Frequency Magnetron Co-Sputtering Method

Abstract

In this paper, we report on the fabrication of Ga-doped zinc oxide (GZO) channel ultraviolet (UV) phototransistors. Under dark measurement conditions, it is found that the values of μFE, VT, SS, and ION/IOFF of the fabricated device are 25.8 cm2/Vs, 0.35 V, 0.2 V/decade, and 1 × 105, respectively. Unpassivated devices have a negative VTH shift with positive bias stress, which results from the interactions of the moisture present in air with the GZO channel during the fabrication procedure and/or storage. Furthermore, it is found that the deep-UV to visible-rejection ratio can reach 1.1 × 102 for the fabricated phototransistor. These electro-optical properties indicate that the fabricated devices not only present good performance as thin-film transistors (TFTs), but are also useful for deep-UV light sensing applications.