Investigations of Photoelectric Phenomena on p‐type Germanium with Dislocations

Steady state and transient photoconductivity are investigated in plastically bent p‐type Ge. At low temperatures a trapping effect is observed. All characteristics of photoconductivity are qualitatively the same as for plastically deformed n‐type Ge in which recombination occurs through dislocations. The experimental results are explained on the basis of a barrier model of recombination at dislocations assuming that in p‐type Ge a dislocation which gives up the unpaired electrons to the valence band becomes positively charged. It is found (from experiment) that the dislocation donor level lies (0.28 ± 0.02) eV above the top of the valence band at 0 °K. The comparison with previous results obtained for n‐type Ge shows that the location of the donor as well as of the acceptor dislocation level is approximately the same in the energy gap. This result is consistent with the assumption that the states connected with the broken bonds at dislocation form an one‐dimensional energy band.