Capacitance-transient spectroscopy on irradiation-induced defects in Ge

Recent studies of roorn-temperature irradiation-induced defects in Ge using space-charge capacitance-transient spectroscopy are reviewed, From these measurements only two defect complexes have been unambiguously identified until now: the E-center (the group-V impurity -vacancy pair) and the A-center (the.interstitial oxygen-vacancy pair). However, contrary to silicon where each of these centers introduces only one energy level, in genuanium the E-center has three energy levels Corresponding to four charge states (=, -, 0, +), and the A-center has two levels corresponding to three charge states (=, -, 0). Another feature specific to each material is the anneal temperature. Both centers disappear below 150 degrees C in gerinanium, whereas in silicon the E-center anneals out at 150 degrees C, depending on the charge state, and the A-center is stable up to 350 degrees C.