High Room Temperature Hole Mobility In $Ge_{0.7}Si_{0.3}/Ge/Ge_{0.7}Si_{0.3}$ Modulation Doped Heterostructures In The Absence Of parallel Conduction

摘要

Recently there has been a lot of interest in two dimensional hole gas systems in pure germanium channels, since Ge has the highest intrinsic bulk hole mobility of all the commonly employed semiconductors, being comparable to the electron mobilites in bulk Si. Konig et. al. [l] have reported a maximum extrinsic transconductance of 125mS/mm(290mS/mm) at 300K(77K) in these Ge channel FETs. However, the hole mobility achieved in these systems are limited by roughness scattering at the alloy-Ge interface at low temperatures and by parallel conduction at high temperatures. Engelhardt et. al. [2] have reported a maximum hole mobility of $1300cm^2/Vs$ at room temperature with the channel density changing by about 50% from 4.2K to 300K, indicating the presence of parallel conduction.