Scattering mechanisms in high-mobility strained Ge channels

We report on the low-temperature mobility in remotely doped p-type strained Ge layers on relaxed Si0.3Ge0.7 virtual substrates, grown by low-energy plasma-enhanced chemical vapor deposition. A maximum mobility of 120 000 cm2 V−1 s−1 has been reached at 2 K, at a carrier sheet density of 8.5×1011 cm−2. Analysis of the mobility and Dingle ratio τ/τq as a function of sheet density suggests that remote impurity scattering is the limiting factor at low sheet densities, but that interface impurities become more important as the sheet density increases.