Electron transport through strained ${\mathrm{Si}}_{1-x}{\mathrm{Ge}}_x∕\mathrm{Si}∕{\mathrm{Si}}_{1-x}{\mathrm{Ge}}_x$ quantum well embedded in relaxed $n\text{−}{\mathrm{Si}}_{1-y}{\mathrm{Ge}}_y$/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 Schrödinger 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 ${\mathrm{Si}}_{1-x}{\mathrm{Ge}}_x$ 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 $(V_{\text{bias}}>0.8–1.0\mathrm{V})$, thermally activated transfer determines the electric current passing through the structure.

• Received 17 October 2006

DOI:https://doi.org/10.1103/PhysRevB.75.115336