Measurements of the Surface Quantization in Silicon n - and p -Type Inversion Layers at Temperatures above 25 K

For an inverted semiconductor surface with a channel of minority carriers at the surface we show that, at sufficiently low temperatures, the Fermi-level position at the surface differentiated with respect to the number of minority carriers in the inversion layer has a characteristic minimum due to quantization of the motion perpendicular to the surface of the charge carriers in the inversion layer. This minimum can be experimentally determined by measuring the gate-bulk capacitance of a metal-oxide-semiconductor transistor (MOST). Experiments with silicon n- and p-type inversion layers demonstrate the quantization in the temperature range of about 25-75 K. Moreover, the effect of charged interface centers in the MOS system is investigated. These charges cause a broadening of the quantized energy levels for the motion perpendicular to the surface.