InxGa1-x As quantum-well high-electron-mobility transistors with a record combination of f(T) and f(max): From the mobility relevant to ballistic transport regimes

We report InxGa1-xAs quantum-well (QW) high-electron mobility transistors (HEMTs) with an outstanding combination of DC and high-frequency characteristics. In particular, we explored the impact of the indium mole fraction in the InxGa1-xAs QW channel from the viewpoint of epi-layer structures, and the comprehensive L-g scaling behavior from the mobility relevant regime to the ballistic regime from 10 mu m to sub-30 nm. To fully understand both DC and high-frequency characteristics of those devices, we physically modeled experimental figures of merit (FOMs), such as DC maximum transconductance and DIBL, only with physical and geometrical parameters of apparent mobility (mu(app)), saturation velocity (v(sat)) and aspect ratio (gamma). Then, we correlated those experimental DC FOMs to high-frequency FOMs, such as cutoff frequency (f(T)) and maximum oscillation frequency (f(max)). Not only was our physical approach presented in this work capable of explaining all the DC and high-frequency characteristics, but the fabricated composite- In0.8Ga0.2 As HEMT with L-g = 30 nm also represented the best balance of f(T) and f(max) in any transistor technology.