Field induced quantum confinement in Indirect Semiconductors: Quantum mechanical and modified semiclassical model

Going beyond the existing semiclassical approach to calculate band-to-band tunneling (BTBT) current we have developed a quantum mechanical model incorporating confinement effects and multiple electron and hole valleys to calculate the tunnel current in a tunnel field-effect transistor. Comparison with existing semiclassical models reveals a big shift in the onset of tunneling due to energy quantization. We show that the big shift due to quantum confinement is slightly reduced by taking penetration into the gate dielectric into account. We further propose a modified semiclassical model capable of accounting for quantum confinement.