Optical and structural investigation of stacked Ge quantum dots

Stacked Ge quantum dots were grown on Si(100) by ultra-high vacuum chemical vapor deposition(UHV/CVD). The morphology and the size distributions of stacked Ge dots were investigated by AFM and TEM. The influences of the number of layers and thickness of Si spacer layers on upper Ge dots were investigated. Results show that the total density of upper Ge dots decreases with increasing of the number of layers. To obtain vertical correlated Ge dots, the thickness of Si spacer layers should be smaller than 48nm. Obvious blueshift (87meV) observed from PL spectrum under 10K demonstrates strong quantum confinement in Ge dots. FWHM of Go dots NP peak is about 46meV that indicates the narrow size distribution of stacked Ge dots grown by UHV/CVD. Finally, a photodetector using stacked Go quantum dots as active region was demonstrated as well.