Transition processes occurring under continuous and stepwise heating of GaAs surface-barrier structures

Evolution of the capacitance-voltage (C-U) and current-voltage (I-f -U and I-r-U) characteristics of solid metal-semiconductor structures (Ni/GaAs) in the process of their continuous and stepwise heating are studied. Properties of the initial structures obey the theory of thermionic emission. It has been shown that as a result of continuous heating, the rectifying structures become ohmic at a temperature of T-Ohm = 720 K, which is substantially lower than the melting points of the metal or the metal-semiconductor eutectic. For comparison, properties of the structures annealed at different temperatures T-ann are measured after cooling to room temperature (stepwise heating). In this case, I-U characteristics are closer to the initial ones for annealing temperatures T-ann < T-0 = 553 K; for T-ann > T-0 , the characteristics display excess currents; and, finally, for T-ann exceeding T-0 by 200-300 K, the characteristics become purely ohmic. It is suggested that these effects are due to a chemical interaction between Ni and GaAs, which changes the properties of the semiconductor surface. (C) 2001 MAIK "Nauka/Interperiodica".