Annealing and temperature dependences of the electrical activity of grain boundaries in germanium observed by SENVEBIC techniques

The electrical activity of grain boundaries in polycrystalline germanium has been studied from SEM/EBIC observations. The effect of two successive thermal treatments (T = 810 °C, t = 2 h and T = 400 °C, t = 50 h) has been examined. Measurements of EBIC profiles across unactive grain boundaries were carried out at different temperatures between 140 K and 300 K and for several injection currents. The inversion of contrast observed at high injection level and low temperature has been analysed in terms of a trapping/recombination transition on a near valence band level (Et = Ev + 0.03 eV)