Depletion region formation at low temperatures

The response of the semiconductor device at low temperatures is limited by the time taken for the formation of the depletion region. Hence the capacitance-voltage characteristics of the semiconductor device containing a junction displays dispersion. This paper reports a study of the dispersion caused in the accumulation and depletion regions of the C-V curve in n-channel MOS devices and in the depletion region of a one-sided n⁺p junction. The authors identify the dispersion in the 30-45 K temperature range as being due to substrate time constant effects and not due to dopant atom emission time constant effects. From the measured admittance as a function of temperature and frequency, the acceptor energy level is determined to within ±0.4 meV