Ballistic transport in state-of-the art In0.65Ga0.35As/In0.52Al0.48As quantum-well high-electron-mobility transistors at room and cryogenic temperatures

This paper presents a systematic analysis of ballistic transport in state-of-the-art In0.65Ga0.35As QW HEMTs at both room and cryogenic temperatures. We examine devices with a wide range of gate lengths from 300 nm to sub-100 nm, to study near-ballistic transport, particularly in terms of ballistic mobility and mean-free-path, especially at 4 K. We also consider the impact of channel carrier degeneracy in the In0.65Ga0.35As QW channel layer, which arises from the relatively low density of states in this layer. Our work underscores the significant role of ballistic mobility in state-of-the art In0.65Ga0.35As HEMTs from 300 K to 4 K. It reveals that quantum-mechanical ballistic transport and channel degeneracy must be accounted for during device modeling and characterization. Furthermore, we propose a methodology to graphically determine whether carrier transport is governed by conventional diffusive transport or near-ballistic transport in terms of channel carrier degeneracy and Lg at each temperature ranging from 300 K to 4 K.