ELECTRICAL-PROPERTIES OF HIGH-ENERGY SN-120 IMPLANTATION IN GAAS

Single crystal n-GaAs substrates have been implanted at room temperatu re with Sn-120 ions at an energy of 70 MeV. The optical microscope and scanning electron microscope studies of the cross section of the impl anted samples have shown the formation of two sharp layers at a depth of 8.7 and 11 mu m from the surface of the substrate. The electrical c haracteristics of the Schottky diodes fabricated on the implanted subs trates at room temperature indicate the presence of high series resist ance due to radiation defects. The electrical properties of the implan ted samples were investigated after implantation and annealing to 850 degrees C. Low temperature resistance measurements of these samples in dicate that the samples annealed to 450 degrees C are dominated by a v ariable range hopping conduction mechanism, whereas for the samples an nealed at 550 and 650 degrees C the electrical conduction is due to ho pping between the neighboring defect sites. At annealing temperatures higher than 650 degrees C, the electrical transport below room tempera ture seems to be dominated by carriers in the extended states, which a re also responsible for the electrical conduction at room temperature and above, for the samples annealed at temperatures higher than 450 de grees C. (C) 1997 American Institute of Physics. [S0021-8979(97)06421- 9].