NITROGEN IN GERMANIUM - IDENTIFICATION OF THE PAIR DEFECT

Several nitrogen-related centers have been introduced by ion implantat ion of nitrogen into germanium and studied by infrared-absorption spec troscopy. Two local vibrational modes at 825.3 and 658.6 cm(-1) were e specially prominent. Measurements on annealed samples implanted with e ither pure N-14 or N-15, or implanted with both isotopes showed these modes to arise from a nitrogen pair defect analogous to one previously suggested to occur in silicon. Based on this and ab initio pseudopote ntial cluster theory, a model of the pair is proposed which is consist ent with the observed infrared absorption. This model is similar to th at of the nitrogen pair in silicon and offers an explanation of the lo w donor efficiency of nitrogen in germanium. Several other nitrogen-re lated local vibrational modes are also observed in the implanted mater ial.