ANISOTROPY OF PIEZORESISTANCE IN N-CHANNEL INVERSION-LAYERS OF METAL-OXIDE-SEMICONDUCTOR TRANSISTORS ON (001)SI

The crystallographic orientation dependence of piezoresistance of n-channel inversion layers in metal-oxide-semiconductor field-effect transistors on p-type (001)Si has been studied by using a diaphragm at room temperature. The experimental results have been compared with self-consistent calculations based on a surface quantization effect. The main feature of the crystallographic orientation dependence can be explained by an electron repopulation effect induced by applied strain and an effective mass anisotropy. It can be found that the difference between longitudinal and transverse piezoresistance in the devices nearly along the [110] directions is mainly due to an orthorhombic distortion of Si, and the shear deformation coefficients Ξu is determined to be 5.8 eV from comparing the experimental results with the calculated ones. An expression of the shear piezoresistance component π44 is also derived.