Trapping and Detrapping Mechanisms in β-Ga₂O₃ Vertical FinFETs Investigated by Electro-Optical Measurements

We present a detailed investigation of the trapping and detrapping mechanisms that take place in the gate region of β-Ga
₂
O
₃
vertical finFETs and describe the related processes. This analysis is based on combined pulsed characterization, transient measurements, and tests carried out under monochromatic light, with photon energies between 1.5 and 5 eV. The original results presented in this article demonstrate that: (i) when submitted to positive gate stress with V
_GS
> 3 V, the devices show a significant threshold voltage variation; (ii) this effect is not recoverable in 10000 s in rest condition (zero bias, dark condition). (iii) VTH can quickly recover its initial value when the device is illuminated with UV-C light at 280 nm. (iv) Stress-recovery experiments carried out at different photon energies allowed us to estimate the threshold energy for the release of carriers from the Al
₂
O
₃
/Ga
₂
O
₃
interface, and for the injection of electrons from metal to the Al
₂
O
₃
insulator (conduction band discontinuity at the metal/Al
₂
O
₃
interface).