Peculiarities of recombination processes in Czochralski (Cz) grown Ge wafers of n-and p-type material are investigated. Recombination characteristics in n-Ge implanted with Co, Fe, Ti, Ni, and Cr are studied before and after annealing. A decrease of the carrier lifetime with increasing doping density has been observed both for n-and p-type Ge using the same excitation level. This decrease is analysed by assuming an increase of the concentration of recombination centres with increasing doping

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... sity. Introduction of metal impurities by ion implantation leads to a decrease of carrier lifetime values. The increase of lifetime with increasing excitation level in the metal-implanted samples implies the formation of acceptor-like slow recombination centres. A photoconductivity quenching effect has been observed in all the implanted samples indicating the existence of centres of fast recombination, related with metal implants, competing with those of slow recombination.