Recombination peculiarities in doped Ge

Abstract

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 density. 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.