Optical and electrical characteristics of GaAs implanted with high energy (70 MeV) ↑(120)Sn ions

摘要

Infra-red transmission and electrical characteristics of single crystal GaAs substrates implanted with 70 Me V ↑(120)Sn ions have been investigated after implantation and subsequent annealing treatments. The optical density αx is found to increase with implanted dose over photon energy range 0.6-1.4 eV and reaches a high saturated value for the samples implanted to a dose of 1 × 10↑(14) ions/cm↑(2) The saturation of αx versus hv suggests amorphisation. Annealing of higher dose samples above 350℃ reduces the density of the radiation defects. The deep lying states seem to be annealing out faster for the annealing temperatures below 450℃ while annealing of near band edge damage occurs over the annealing temperature range of 450-600℃. The resistance values of the high dose (1×10↑(14) ions/cm↑(2)) samples which is initially low (≤ 1 kΩ), are found to Increase with annealing temperatures upto 650℃ and then decrease for higher annealing temperatures. The resistance of the samples annealed up to 450℃ is dominated by variable range hopping conduction below room temperature. For the samples annealed at temperatures higher than 450℃, the electrical transport is dominated by hopping between the neighbouring defect sites. Above 650℃ annealing temperatures, the defect states are further reduced and the conduction mechanism is dominated by carriers in the extended states. # 1998 Elsevier Science Ltd. All rights reserved