Hybrid Boltzmann transport-Schrodinger equation model for quantum well injection transit (QWITT) diodes

The authors report a self-consistent study of steady-state nonstationary transport in QWITT diodes using the pure state tunneling theory to treat transport through the double barrier quantum well region and the Boltzmann transport equation (BTE) to treat transport in the rest of the device. The distribution functions at the boundaries of the double barrier structure are evaluated, taking into account both tunneling and phonon scattering processes. It si found that velocity overshoot occurs in a region of 50 nm within the double barrier region, with a peak velocity of about 8*10/sup 7/ cm/sec occurring immediately after injection. The velocity falls rapidly to 7-8*10/sup 6/ cm/sec over a distance of 50 nm. Due to the high energy of carriers injected from the quantum well and the presence of high electric fields, the extent of the velocity overshoot in the drift region of QWITT diodes is limited.<>