Strain effects on performances in InAs HEMTs

We investigate the effects of the strain on the performances in the nano-scale HEMTs with the InAs and the InAs-related channels. The drain current, I_ds, and the intrinsic transconductance, g_m0, increase as the In content, x, in the channel increases, which is because of the decrease of the effective mass, m*, in the G valley. This indicates the superiority of the InAs channel in terms of the current drivability. In case of the In_0.52Al_0.48As barrier/buffer, the compressive strain makes m* large in the InAs channel, which leads to the decrease of I_ds and g_m0. However it makes the impact ionization threshold energy, E_th, large, which leads to the suppression of the impact ionization. In case of the AlSb barrier/buffer, the tensile strain makes m* small in the InAs channel, which leads to the increase of I_ds and g_m0. However it makes E_th small, which leads to the promotion of the impact ionization. In conclusion, the InAs channel with the AlSb barrier/buffer is preferable for attaining the high current drivability, even though it is restricted within the narrow limits of the low V_ds applications.