Temperature-lowering-induced enhancement of ballistic transport in a 100-nm Γ-gate AlGaAs/InGaAs pseudomorphic HEMT

We investigated the (ballistic) current-voltage (I-V) characteristics in a 100-nm Γ-gate AlGaAs/InGaAs Pseudomorphic high-electron-mobility transistor (pHEMT) as a function of temperature for temperatures ranging from 300 K to 10 K and analyzed the transport in terms of carrier backscattering. We observed that the drain current in the linear region dramatically increased below 60 K due to reduced phonon scattering. The critical temperature where the drain current started to rapidly increase shifted to a higher value as the drain voltage was increased. These results are in good agreement with the ballistic transport theory in which low temperatures and high electric fields along the channel lead to enhanced ballistic transport due to a reduction in the backscattering probability. We also carried out self-consistent Schrodinger-Poisson band profile calculations to understand the experimental data.