Electron confinement potential in etched Si/SiGe quantum dots

We present an analysis of the confinement potential in etched Si/SiGe dot arrays fabricated from a high electron mobility Si/SiGe heterojunction. The free electrons in the dots are investigated by far-infrared magnetospectroscopy. The analysis of the resonances associated with the plasmon modes provides a determination of the confining potential, the electron population in the dots, the negative surface charge on the etched sidewalls, and the lateral depletion length. The confinement potentials calculated by a simple electrostatic model without any adjustable parameters are found to be in very good agreement with the experimental data.