Characterization of Subgap Density-of-States by Sub-Bandgap Optical Charge Pumping in In0.53Ga0.47As Metal-Oxide-Semiconductor Field-Effect Transistors

Abstract

We report an experimental characterization of the interface states (D-it(E)) by using the subthreshold drain current with optical charge pumping effect in In0.53Ga0.47As metal-oxide-semiconductor field-effect transistors (MOSFETs). The interface states are derived from the difference between the dark and photo states of the current-voltage characteristics. We used a sub-bandgap photon (i.e., with the photon energy lower than the bandgap energy, E-ph < E-g) to optically excite trapped carriers over the bandgap in In0.53Ga0.47As MOSFETs. We combined a gate bias-dependent capacitance model to determine the channel length-independent oxide capacitance. Then, we estimated the channel length-independent interface states in In0.53Ga0.47As MOSFETs having different channel lengths (L-ch = 5, 10, and 25 [mu m]) for a fixed overlap length (L-ov = 5 [mu m]).