Hysteresis-free Ga2O3 solar-blind phototransistor modulated from photoconduction to photogating effect

Abstract

High tunability of photoresponse characteristics under work conditions is desired for a single solar-blind photodetector to be applied in multifarious fields. Three-terminal metal–oxide–semiconductor field-effect phototransistors have shown excellent controllability of performance, but the hysteresis issue impedes their stable operation. In this work, the metal–semiconductor field-effect phototransistor based on the exfoliated Ga2O3 microflake and graphene thin film is demonstrated. The high-quality quasi-van der Waals interface between Ga2O3 and graphene eliminates the hysteresis issue and generates a subthreshold swing as low as 69.4 mV/dec. By regulating gate voltage (Vg), the dominated mechanism of photocurrent generation in the device can be tuned continuously from the fast photoconduction effect to photogating effect with high photogain. Accordingly, the responsivity, dark current, detectivity, rejection ratio, and decay time of the device can be well adjusted by the Vg. At Vg = −1 V and a source to drain voltage of 2 V, the device shows excellent performance with a responsivity of 2.82 × 103 A/W, a rejection ratio of 5.88 × 105, and a detectivity of 2.67 × 1015 Jones under 254 nm illumination. This work shows the possibility of realizing highly tunable solar-blind photodetectors to meet the requirements for different application fields by introducing gate voltage modulation.

Efficient Suppression of Persistent Photoconductivity in β-Ga2O3-Based Photodetectors with Square Nanopore Arrays

“…However, when the light is turned off, the photocurrent exhibits a very slow decay with a strong PPC effect. This result is similar to that reported in a previous study. − Oxygen vacancies ( V o ) are photoionized into shallow donor states (Vo 2+ ) by DUV light, and the photogenerated carriers are captured on other defects, which is the main reason for the strong PPC effect . The slow decay of the photocurrent in the β-Ga 2 O 3 microflakes hinders its application for solar-blind PDs.…”

“…Large photoconductive gains often generate persistent photoconductive (PPC) effects because their defects trap minority carriers, resulting in slow recovery rates ranging from minutes to hours. − This phenomenon is very common in oxide semiconductors with numerous oxygen vacancies ( V o ) and a high density of defects. , However, in some devices based on β-Ga 2 O 3 microflakes, the PPC effect has been effectively suppressed. For example, Chen et al fabricated β-Ga 2 O 3 microflake-based PD with high photoconductive gains and fast response .…”

Integrating 2D layered materials with 3D bulk materials as van der Waals heterostructures for photodetections: Current status and perspectives

“…Recently, Tan et al demonstrated a solar‐blind metal–semiconductor field‐effect phototransistor (MESFEPT) with an exfoliated Ga 2 O 3 microflake as the channel and a graphene thin film as the top gate 126 . The high‐quality van der Waals contact between Ga 2 O 3 and graphene gate results in an excellent gate modulation performance with negligible hysteresis and an extremely low subthreshold swing of 69.4 mV dec −1 .…”

High-Performance Diamond Phototransistor with Gate Controllable Gain and Speed

“…Three-terminal field-effect phototransistors exhibit high photoresponse controllability and excellent performance by introducing gate modulation. In addition, responsivity ( R ), detectivity ( D *), dark current, and rejection ratio of phototransistor can be tuned in a wider range by applying different gate voltages ( V G ). − The excellent performance tunability for three-terminal devices provides a great and vast potential application. It is well-known that the practical application of photodetectors requires fast response speed, high signal-to-noise ratio, and low-energy consumption.…”