Publication Date:
2016-06-07
Description:
We report the magneto-transport, scattering mechanisms, and effective mass analysis of an ultra-low density two-dimensional hole gas capacitively induced in an undoped strained Ge/Si 0.2 Ge 0.8 heterostructure. This fabrication technique allows hole densities as low as p ∼ 1.1 × 10 10 cm −2 to be achieved, more than one order of magnitude lower than previously reported in doped Ge/SiGe heterostructures. The power-law exponent of the electron mobility versus density curve, μ ∝ n α , is found to be α ∼ 0.29 over most of the density range, implying that background impurity scattering is the dominant scattering mechanism at intermediate densities in such devices. A charge migration model is used to explain the mobility decrease at the highest achievable densities. The hole effective mass is deduced from the temperature dependence of Shubnikov-de Haas oscillations. At p ∼ 1.0 × 10 11 cm −2 , the effective mass m * is ∼0.105 m 0 , which is significantly larger than masses obtained from modulation-doped Ge/SiGe two-dimensional hole gases.
Print ISSN:
0003-6951
Electronic ISSN:
1077-3118
Topics:
Physics
