On Effects of Gate Bias on Hole Effective Mass and Mobility in Strained-Ge Channel Structures

The effects of gate bias on hole effective mass (m*) and Hall mobility were studied in strained-Ge channel modulation-doped structures. Shubnikov-de Haas oscillations were analyzed with and without the bias and a significant m* increase from 0.15 to 0.22m(0) was observed with the increase in the carrier density due to the strong nonparabolicity of the valence band. This is a clear demonstration that modification of carrier density via gating considerably affects m*, which may have critical effects on device properties. The gate bias dependence of Hall mobility was also investigated and the dominant scattering mechanism was clarified in various temperature and carrier density regions, (c) 2008 The Japan Society of Applied Physics.