Microscopic study of the vacancy and self-interstitial in Germanium by PAC

We have employed two different techniques of Frenkel pair production in combination with the Perturbed Angular Correlation method (PAC) to study and identify the basic intrinsic defects in Germanium. In one of the techniques the PAC probe atom In-111 serves as primary knock-on atom due to a 29 eV recoil energy from a neutrino produced in the nuclear decay of the probe's precursor, Sn-111. This leads to the production of single Frenkel pairs with the In-111 probe adjacent to a vacancy identifying this defect. In the other technique the Ge crystals are electron irradiated leading to the trapping of two different defects at the In-111 probes. Detailed studies of this trapping behavior as function of temperature and Fermi level are performed. One of the trapped defects is identified as the monovacancy from comparison with the neutrino recoil experiment, the second defect is assigned to a trapped self-interstitial. This assignment is based on exclusion of alternatives on the one hand and by indirect kinetic information from the neutrino recoil. An acceptor state for the vacancy at E-v + 0.20 eV is deduced. Long range migration of the neutral vacancy and the interstitial takes place at 200(5)K and 220(5) K, respectively.