Resonant tunneling versus thermally activated transport through strained Si1-xGex/Si/Si1-xGex quantum wells

Electron transport through strained Si1-xGex/Si/Si1-xGex quantum well embedded in relaxed n-Si1-yGey/strained Si emitter and collector was analyzed and numerically simulated taking into account the two main processes that are resonant tunneling and thermally activated transfer through the barriers. These processes were modeled with a system of Schrodinger and kinetic equations resolved self-consistently with the Poisson equation. Within the optimum domain of composition (0.09 < y < 0.25, 0.56 < x < 0.83) and thickness providing defect free strained Si and Si1-xGex layers, it has been found that resonant tunneling dominates over the transport mediated by the thermally activated charge transfer for low applied voltages. Peak-to-valley ratio reaches 11 at room temperature. At high voltages (V-bias>0.8-1.0 V), thermally activated transfer determines the electric current passing through the structure.