Radiative recombination in germanium as an indicator of radiation damage

Abstract

It is shown that the radiative recombination of electron-hole pairs from a semiconductor can be used as a monitor of minority-carrier lifetime. By observing the change in the radiative signal under electron-bombardment from n- and p-type germanium for a wide range of majority carrier concentrations, it is shown that a single type of recombination center can account for the minority-carrier lifetime. This level is located at either 0·21 eV from the conduction band or 0·28 eV from the valence band, and has a capture probability for minority holes 24 times that for minority electrons. This technique can be used for the study of radiation damage in other semiconductors where electron-hole radiative recombination has been observed. A prime attribute of the method is that changes in minority-carrier lifetime can be detected in material whose initial lifetime can be of the order of 10 −10 sec.