Optoelectronics Based on SiGe/Si Heterostructures

摘要

The overall objective of the research was to explore SiGe/Si heterostructures foroptoelectronics applications. We have extensively investigated intersubband transitions of Si/Ge quantum structures including p-type Si quantum well, n-type Si(110) quantum wells, and n-type Ge(001) quantum wells. We have also studied many-body effects on the intersubband transitions. The application of these transitions for the fabrication of tunable normal incidence infrared detectors has been demonstrated. In the area of optical properties, we have also demonstrated a large Stark shift in type II SiGe/Si multiple quantum wells and luminescence from Si(sub m)Ge(sub n) superlattices. In the area of transport properties, we have studied the in-plane mobility of coupled delta doped quantum wells as a function of spacing between the wells. An enhancement of hole mobility above that of the Si was found due to the penetration of wavefunctions into the spacer where the impurity scattering is minimal. In addition to exploration of new devices, alternative growth techniques for achieving the layer thickness to the monolayer scale and doping control were also investigated. In the area of the growth control of SiGe epitaxial layers, we have constructed a gas source molecular beam epitaxy 5 stem. We have investigated the orientation dependence of as beam epitaxy. Selective epitaxy growth on SiO2-masked substrates has been demonstrated. We have also studied the role of surfactants for obtaining high quality coherently strained SiGe epitaxial layers and for providing doping control in quantum wells an superlattices. jg.