High Hole Mobility SGOI Substrates Obtained by the Germanium Condensation Technique

Abstract

Thin SGOI substrates with Ge content from 42 to 93% have been produced by the Ge condensation technique and full structural characterization has been carried out. In a second step, the electrical properties of these substrates have been analyzed by the pseudo-MOSFETs technique which allowed the determination of the carrier low field mobilities as well as the density of fixed charges in the buried oxide (BOX) and the density of interface traps at the BOX-SiGe film interface. Optimization of intermediate anneals in argon during the condensation process has made the production of high crystalline quality and high mobility substrates possible (up to 400 cm2/Vs for a 93% SGOI). Opposite trends were observed for holes and electrons: while the hole mobility is increasing with increasing Ge content, the electron mobility decreases. Moreover, the density of interface traps and the density of oxide charges were found to increase with increasing Ge content.