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

Single crystal p-GaAs substrates have been implanted at room temperature wi th Sn-120 ions at an energy of 70 MeV to a fluence of 1x10(14) ions/cm(2). The implanted samples are annealed at different temperatures up to 850 degr ees C in hydrogen ambient. The resistance values are found to increase with increasing annealing temperature up to 550 degrees C and then decrease for higher annealing temperatures. Low temperature resistance measurements of the samples annealed at 450 degrees C indicate that the transport <200 K is dominated by variable range hopping conduction mechanism, whereas for the samples annealed at 550 degrees C, the electrical conduction is due to hopp ing between the neighboring defect sites. The conduction mechanism for the samples annealed at 650 degrees C is in the extended states at all temperat ures but the behavior is similar to that due two accepters partly compensat ed by a donor. On further annealing at 750 degrees C the resistance of the sample is reduced further and the conduction mechanism is possibly due to c arriers in the extended states governed by a single acceptor level, which i s also responsible for the electrical conduction at room temperature and ab ove, for the samples annealed at temperatures higher than 450 degrees C. (C ) 1999 Elsevier Science B.V, All rights reserved.