A method of determining minority carrier lifetime and doping level profiles of low-doped metal-oxide-semiconductor structures using pulsed photoinjection

Abstract

This method. aimed at determining doping level and minority carrier lifetime of low-doped semiconductors (<1014/cm3 in silicon) is based on pulsing the metal-oxide-semiconductor device into deep depletion. A delayed photopulse is then applied to the sample, which causes partial collapse of the depletion region. The changes in fill time and in capacitance versus collected photocharge are measured. The minority carrier lifetime is computed through the dependence of fill time on the magnitude of the photoinjected charge. The doping level is determined by the change in capacitance following the photoinjection. The method is advantageous in (a) independently supplying the doping level and lifetime, (b) being insensitive to edge injection, and (c) enabling the determination of the diffusion length.