Carrier lifetime dependence on doping, metal implants and excitation density in Ge and Si

Results are presented of a comparative study of the dependence of carrier recombination characteristics on excitation and dopant concentration in Si and Ge. The bulk lifetime observations are simulated by combining the Shockley–Read–Hall model with Auger recombination above a doping concentration threshold. It is shown that the bulk carrier lifetime behaviour in Si and Ge is very similar. The lifetime dependence on dopant concentration in germanium can be phenomenologically described by assuming a linear increase of recombination centre concentration with dopant concentration. Recombination characteristics in n-Ge implanted with Co, Fe, Ti, Ni and Cr are studied before and after annealing.