Spin Accumulation and Spin Lifetime in p-Type Germanium at Room Temperature

Abstract

The electrical creation and detection of spin accumulation in p-type Ge were successfully demonstrated at room temperature by spin-polarized tunneling in epitaxial Fe/MgO contacts on Ge with a hole concentration of 8×1018 cm-3. In Hanle measurements, the spin accumulation produces a spin signal of about 40 µV per mA of tunnel current. The extracted spin lifetime of holes is 13 ps, which is much longer than the momentum relaxation time. The corresponding spin-diffusion length is 80 nm, suggesting that communication of spin information in p-type Ge is possible over the typical channel length of a field-effect transistor.