Electrical characteristics of high energy 120Sn implantation in p-type GaAs

Abstract

Single crystal p-GaAs substrates have been implanted at room temperature with 120Sn ions at an energy of 70 MeV to a fluence of 1 × 10 14 ions/cm 2. The implanted samples are annealed at different temperatures up to 850°C in hydrogen ambient. The resistance values are found to increase with increasing annealing temperature up to 550°C and then decrease for higher annealing temperatures. Low temperature resistance measurements of the samples annealed at 450°C indicate that the transport <200 K is dominated by variable range hopping conduction mechanism, whereas for the samples annealed at 550°C, the electrical conduction is due to hopping between the neighboring defect sites. The conduction mechanism for the samples annealed at 650°C is in the extended states at all temperatures but the behavior is similar to that due two acceptors partly compensated by a donor. On further annealing at 750°C the resistance of the sample is reduced further and the conduction mechanism is possibly due to carriers in the extended states governed by a single acceptor level, which is also responsible for the electrical conduction at room temperature and above, for the samples annealed at temperatures higher than 450°C.