Seebeck Coefficient of Ultrathin Silicon-on-Insulator Layers

We measured the Seebeck coefficient of P-doped ultrathin silicon-on-insulator (SOI) layers with thicknesses of 2-100 nm. The dependence of the coefficient on the impurity concentration was investigated, and was shown to be in good agreement with that of bulk Si for Sol thicknesses above 6 nm. In addition, it was found to decrease with increasing impurity concentration, which is usually observed in semiconductor materials. However, for doping levels above 3.5 x 10(19) cm(-3), the Seebeck coefficient was observed to increase. This is likely to be due to the influence of an impurity band. (C) 2009 The Japan Society of Applied Physics