Band structure of III-V thin films: An atomistic study of non-parabolic effects in confinement direction

In this work, the band structure of III-V thin films is calculated by atomistic tight-binding (TB) sp³d⁵s* method. The effect of non-parabolic (NP) dispersion on subband energy level is investigated, by comparing TB results with NP quantization model within the effective mass approximation (EMA). It is found that to match TB subband energy, the NP coefficient in the confinement direction needs to be boosted compared to the theoretical value. The electrostatic characteristics of a Ultra-Thin Body (UTB) Metal-Oxide-Semiconductor capacitor (MOSCAP) are also calculated by solving Poisson and Schrödinger equations self-consistently. It is found that satellite valleys play a role in GaAs thin films at relatively low voltage and need to be taken into account in EMA models with proper energy position.