Role of surface-roughness scattering in double gate silicon-on-insulator inversion layers

The effect of surface-roughness scattering on electron transport properties in extremely thin double gate silicon-on-insulator inversion layers has been analyzed. It is shown that if the silicon layer is thin enough the presence of two Si-SiO₂ interfaces plays a key role, even for a very low transverse effective field, where surface-roughness scattering is already noticeable, contrary to what happens in bulk silicon inversion layers. We have studied the electron transport properties in these devices, solving the Boltzmann transport equation by the Monte Carlo method, and analyzed the influence of the surface-roughness parameters and of the silicon layer thickness. For low transverse effective fields, μ_SR decreases as the silicon layer decreases. However, at higher transverse effective fields, there is a different behavior pattern of μ_SR with T_w since it begins to increase as T_w decreases until a maximum is reached; for lower silicon layer thicknesses, surface-roughness mobility abruptly falls. Finally we have compared the behavior of μ_SR versus T_w for double gate silicon-on-insulator and single gate silicon-on-insulator inversion layers.