EFFECTIVE MASS CHANGE OF ELECTRONS IN SILICON INVERSION LAYERS OBSERVED BY PIEZORESISTANCE

Abstract

Piezoresistance coefficients were determined for n‐type inversion layers at low gate fields on (100), (110), and (111) surfaces of silicon at room temperature. Results deviating from bulk values were found on the (110) and (111) planes. This anomaly can be understood in terms of changed effective masses of conduction electrons on the surface as a consequence of the quantization of the carrier wave function in the surface channel. Good agreement between theoretical results and experiment was found. It was observed that the quantization is efficient even at the threshold voltage (i.e., ∼2×10⁴ V/cm) and occasions the anisotropic piezoresistance on the (110) surface.