Influence of Surface Roughness Scattering on Spin Lifetime in Silicon

Silicon is an ideal material for spintronic applications [1] due to long spin lifetime, however, considerable spin relaxation in gated silicon structures was experimentally observed [2]. Surface roughness scattering determines the transport in the channel at high carrier concentration in thin silicon films [3]. Here we investigate the spin relaxation due to surface roughness. The surface roughness scattering matrix elements are proportional to the square of the product of the subband wave function derivatives at the interface [4, 5]. To find the corresponding matrix elements for spin relaxation we use the effective k∙p Hamiltonian for the two relevant valleys along the OZ-axis [6, 7] with the spin degree of freedom properly included [8-10]. The relaxation time is calculated as a thermal average with the Fermi function ( )