Ferroelectric α-In2Se3 Wrapped-Gate β-Ga2O3 Field-Effect Transistors for Dynamic Threshold Voltage Control

Indium selenide (alpha-In2Se3), which is a recently emerging ferroelectric semiconductor, can solve a major hindrance to applications of an ultra-wide bandgap beta-gallium oxide (beta-Ga2O3) semiconductor. Here, ferroelectric alpha-In2Se3 wrapped-gate beta-Ga2O3 field-effect transistors (FETs) for dynamic threshold voltage (V-TH) control is demonstrated. The dry-transferred alpha-In2Se3 layer is wrapped around beta-Ga2O3 channel, which allows efficient electrostatic gate modulation. Thus, the ferroelectricity of alpha-In2Se3 and a thin native oxide interlayer formed at the interface between beta-Ga2O3 and alpha-In2Se3 can provide effective V-TH control. Applying a positive voltage pulse to the gate electrode induces positive V-TH shift; hence, the device can be even changed from depletion to enhancement (E-) mode. The E-mode beta-Ga2O3 FET exhibits steep-subthreshold slope with a negligible hysteresis. The V-TH of E-mode can be further modulated by applying back-gate bias, and electrical performance can be enhanced via dual-gate operation. The approach demonstrates an energy efficient beta-Ga2O3-based switching device architecture integrated with ferroelectric van der Waals 2D materials.