  In this letter, we report on the theoretical investigations of electron
mobility in practically viable designs of InxGa1-xN channel high electron
mobility transistors (HEMT). Carriers in such devices are expected to exhibit a
higher velocity and hence higher cut-off frequencies (fT) for highly scaled
architectures. We estimate that the mobility of two dimensional electron gas
(2DEG) is limited by alloy scattering rather than phonon scattering unlike in
conventional GaN-channel HEMTs. For indium composition of 0.30, the mobility
and sheet resistance are found to be 500 cm2/Vs and 700 ohm per sq.
respectively, which can severely affect the parasitic voltage drop in access
regions. The results presented here are believed to significantly guide the
practical exploration of InxGa1-xN channel HEMTs towards next-generation
electronics by enabling careful design of device layouts in highly scaled
transistors to minimize parasitic access region voltage drop which results due
to significant degradation of 2DEG mobility.
