Determination of carrier density dependent lifetime and quantum efficiency in semiconductors with a photoluminescence method (application to InGaAsP/InP heterostructures)

The light beam of a laser is focussed near the surface of a semiconductor sample. Thereby the excitation rate can be controlled precisely assuming a Gaussian intensity distribution of the beam. Measuring the recombination light intensity yields the quantum efficiency of the sample. By sinusoidal modulation of the excitation light and measurement of the resulting phase shift of the recombination light, the carrier density dependent lifetime is obtained. By evaluation of measured internal quantum efficiency and phase shift, Auger and radiative recombination coefficients are determined. The analysis takes into account the carrier density dependence of the radiative coefficient and shows that for most experimental conditions carrier diffusion can be neglected. In this case the analysis can be performed without numerical integration. Application of the method to quaternary InGaAsP material yielded values for Auger coefficient and radiative coefficients in accordance with published results.