SiGe Spintronic Devices with High-k Dielectric Gates

SiGe is an attractive material for future advanced electronic devices desired for beyond Moore’s law high performance computing. For spintronic devices in particular, SiGe offers extremely high mobilities that can lead to long spin diffusion lengths and a spin-orbit coupling that can be used to control spin relaxation in spin valves—a prerequisite for any spinFET device. Moreover, SiGe is amenable to scaling and is compatible with most commercial device fabrication facilities in foundries. Here, we grow compressively strained Ge quantum wells with relaxed Si_0.2Ge_0.8 barriers using molecular beam epitaxy. We fabricate devices to determine the basic properties of the films using both charge and spin state variables and perform a systematic study to create a method of growing high-quality high-k dielectrics (hafnia and alumina) by atomic layer deposition to allow gating of these devices. We present magnetotransport results for both the charge- and spin-based devices from 3 K - 300 K at fields up to 2.5 T and compare these results for multiple samples.