Optical properties of hybrid Si1−xGex/Si quantum dot/quantum well structures grown on Si by RPCVD

We experimentally investigated the optical properties of structures consisting of a Si1−xGex/Si quantum well and stacked quantum dots on Si substrates. The Ge composition determined for Si1−xGex quantum wells and dots was approximately 20% and 30%, respectively. Three Raman peaks observed at approximately 520, 410, and 295 cm−1 correspond to vibration of Si-Si, Si-Ge, and Ge-Ge phonons, and a peak related to Si1−xGex quantum dots was observed at 490 cm−1. Photocurrent spectra were dominated by transitions related to the quantum dots and quantum well corresponding to the energy gap and split-off band for Si and energy for Si1−xGex quantum dots and wells.