Site-controlled SiGe islands on patterned Si(001): Morphology, composition profiles, and devices

Deterministic control of position on a substrate, uniform size and shape are prerequisite for most of the envisioned applications of SiGe islands in electronic and optoelectronic devices. As an example of electronic application, tensile strained Si layers on top of coherent SiGe islands may be used as channels for field effect transistors (FETs) with enhanced electron mobility. For such a kind of application, site-controlled islands are required to allow for their external addressability. In this feature article we investigate the morphological and compositional evolution of site-controlled SiGe islands on pit-patterned Si(001) substrates. We then report on the first demonstrated n-channel FET with enhanced electron mobility based on SiGe islands. Finally, a new approach for further increase of the tensile strain is presented.