event
Thursday 03 Nov 2016: Quantum Germanium
Dr Stuart N. Holmes - Toshiba Research Europe Limited, Cambridge Research Laboratory
HAR/170 (3D Visualisation Suite) 12:30-13:30
Ambient temperature mobilities > 4x103 cm2/V.s in strained p-Ge quantum wells have been demonstrated recently. At low temperature the mobility is > 1x106 cm2/V.s matching or even exceeding state-of-the-art values for p-type or even n-type III-V semiconductor heterostructures. We outline the electrical properties of these quantum well, two-dimensional hole gases. The spin-splitting in applied magnetic field is entirely consistent with a Zeeman effect from the heavy-hole, angular momentum J = 3/2 (components mj = ±3/2) state with the spin orientation driven by the biaxial compressive strain with the relaxed Si0.3Ge0.7 barrier layers and is quantised in the growth direction. In narrow, electrostatically defined channels, ballistic quantization of the conductance is observed at 0.5 (2e2/h) without applied magnetic field or source-drain bias. This preliminary study confirms the importance of the role that strained Ge will play in quantum device schemes where long spin-lifetimes are expected at the expense of having weak spin-orbit coupling effects present.
