Surface states and the temperature dependence of microindentation damage in silicon

Abstract

The interrelationship between mechanical and electronic properties of crystalline semiconductors has been explored through indentation of doped single-crystal silicon. The indentations were etched and the damage that extended beyond the immediate contact zone has been measured as a function of isothermal temperature of the silicon during the indentation. The damage zone exhibited a maximum at 150 °C. The surface properties of the silicon have been modeled with a finite, fixed number of surface states which possess an energy within the band gap. The spatial extent (Debye length) of the space-charge region has been calculated as a function of temperature, doping level, surface state energy, and density. The temperature variation of the Debye length is similar to that of the experimentally measured damage zone size when the indentation load was 0.49 N; both range in the 10−6 m and exhibit a maximum with temperature. The model implies that the deformation mode of silicon may be additionally influenced by external applied voltages, suitable doping, and/or surface preparation.