A study was made of the effect of the bombarding-electron energy upon the rate of E4 center (Ec–0.76eV) formation and the temperature dependence of the efficiency of the latter in a neutral volume and in the space-charge region of n–type material. The specimens were Schottky diodes which had been manufactured by depositing Ti onto epitaxial layers of n-type GaAs, with n = 2 x 1015 to 4 x·1015cm3. The defect concentration was obtained by using deep-level transient spectroscopy. It was shown that the number of E4 centers among the total number of irradiation-induced defects increased sharply upon increasing the electron energy from 1.3 to 2.2MeV. It was found that the rate of introduction of E4 centers into the space-charge region did not depend upon the irradiation temperature, and was far higher than that in a neutral volume. In the latter, however, this rate increased non-linearly with irradiation temperature. It was assumed that an E4 center was a complex that consisted of 2 unit defects generated in adjacent sites of the Ga and As sub-lattices due to a single collision. It was noted that its final configuration was the result of an interaction of these defects, which depended upon the dynamics of transformation of their primary charge states.

Formation of E4-Centers (Ec – 0.76eV) in Gallium Arsenide. V.V.Peshev, A.P.Surzhikov: Russian Physics Journal, 2002, 45[2], 91-3