Enhancement of multisubband electron mobility in AlxGa1−xAs Semi-Cubic quantum Well-based HEMT structure

Recently, miniaturisation has encouraged the exploration of new materials and device architectures for enhanced performance of emerging semiconductor devices. Hence, in this work, we design an AlxGa1−xAs semi-cubic quantum well (SCQW) based HEMT structure and improve its multisubband electron mobility (µ) as a function of well width (ww). It is observed that increasing ww reduces ionised impurity (ii-) scattering, resulting in an enhancement in µ. In the absence of an applied electric field (F), the double subband is occupied. However, when F = 10 kV/cm is applied, three subbands are occupied, resulting in a sudden drop in µ, primarily governed by ii-scattering, and marginally by alloy disorder (al-) scattering. Furthermore, µ increases with decreasing well potential height (Vsc) and increasing doping concentration (nd). Also, we show that despite the same design parameters, the change in potential profile in semi-parabolic QW increases the al-scattering, which makes µ (SCQW) >µ (SPQW). The above analysis will significantly contribute to the advancement of non-square quantum well-based HEMT devices for 5/6G applications.