Optical and electrical characterization of SiGe layers for vertical sub-100 nm MOS transistors

The fabrication of n- and p-vertical advanced heterostructure MOS (VAHMOS) transistors involves pseudomorphic growth of SiGe alloys on Si as well as o n relaxed buffer layers. SiGe layers grown by molecular beam epitaxy (MBE) and chemical Vapor deposition (CVD) have been investigated with optical and electrical spectroscopy with respect to material quality, composition and defect concentration. Modulation doped samples grown by CVD showed higher p hotoluminescence (PL) efficiency compared to undoped samples with similar l ayer structures and growth conditions. PL measurements together with X-ray analysis of samples grown by MBE with a high Ge fraction (30-50%) indicated no disorder and no relaxation. Photocurrent (PC) measurements and deep lev el transient spectroscopy (DLTS) were used to identify various defects givi ng rise to electrically active deep levels. (C) 1998 Published by Elsevier Science S.A. All rights reserved.