The PI will explore the electronic device potential of heterostructures using germanium-silicon alloys. The investigations to be performed will permit evaluation of the potential of germanium- silicon heterostructures, in particular for application to heterojunction bipolar transistors. Basic studies of film growth using advanced gas phase epitaxy, including determination of critical thickness for commensurate growth will be used. Doping effects and the processes of oxidation and diffusion which are not yet well understood will also be examined. Abrupt multilayered structures will be grown and a variety of analytic techniques will be brought to bear for film characterization. In particular, will be performed the growth and evaluation of heterojunction bipolar transistor structures which may be of great importance as high speed switching devices. Research performed in this project will also permit the investigating of the future advanced heterojunction concepts which involve the use of sheets of dopant atoms. These studies will advance the understanding of heterojunctions in general and will lead to improved understanding of important devices.