ELECTRICAL-PROPERTIES OF 2-DIMENSIONAL ELECTRON GASES GROWN ON CLEANED SIGE VIRTUAL SUBSTRATES

The low temperature electrical properties of modulation-doped two-dime nsional electron gases (2DEG) in the SiGe system were studied. The eff ect on the electrical properties of removing the substrate from the gr owth chamber after the growth of the virtual substrate, chemically cle aning the virtual substrate and then growing the 2DEG on a thin SiGe b uffer were investigated. The results demonstrate that the carrier dens ity and mobility decrease as the regrowth interface is moved closer to the 2DEG. Lower temperature desorption of the passivating chemical ox ide improves the mobility and carrier density when a regrowth interfac e is close to the quantum well. The mismatch of Ge content in the virt ual substrate and the heterolayers was also shown to produce a reducti on in the carrier density and mobility. Crown Copyright (C) 1998 Publi shed by Elsevier Science S.A. All rights reserved.