Single crystal n-GaAs substrates have been implanted at room temperature with 120Sn ions at an energy of 70 MeV. The optical microscope and scanning electron microscope studies of the cross section of the implanted samples have shown the formation of two sharp layers at a depth of 8.7 and 11 μm from the surface of the substrate. The electrical characteristics of the Schottky diodes fabricated on the implanted substrates at room temperature indicate the presence of high series resistance due to radiation defects. The electrical properties of the implanted samples were investigated after implantation and annealing to 850 °C. Low temperature resistance measurements of these samples indicate that the samples annealed to 450 °C are dominated by a variable range hopping conduction mechanism, whereas for the samples annealed at 550 and 650 °C the electrical conduction is due to hopping between the neighboring defect sites. At annealing temperatures higher than 650 °C, the electrical transport below room temperature seems to be dominated by carriers in the extended states, which are also responsible for the electrical conduction at room temperature and above, for the samples annealed at temperatures higher than 450 °C.

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It is well known (1–4) that substantial amounts of chlorine can be incorporated in normalHCl grown thermal oxides on silicon to effectively passivate sodium ions. It has been of interest to find out if similar effects can be obtained for oxides chlorinated by implanting Cl ions at the surface of SiO2 films on Si. It appears (5, 6), however, that when these films are annealed at temperatures in excess of 700°C, no Na neutralization property is evident. In this paper, we show with the help of 4He ion Rutherford backscattering (RBS) experiments on chlorine implanted into a thermal oxide film on Si that the oxide loses about 10 (50) percent of the implanted Cl during annealing at 600°C (1100°C) in nitrogen for 30 min. We obtain the diffusion coefficient D of Cl in SiO2 at various temperatures with the help of a process simulation program (SUPREM II) and show that for D∼D0expfalse(−Enormala/normalkTfalse) , D0=10−12 cm2/normals and Enormala∼0.5 normaleV . Corrections for system resolution and energy straggling effects are made to obtain the actual Cl density profiles in the SiO2 film. It is seen that Cl at 50 keV has a range of 440Å in SiO2 with a standard deviation of 220Å for a gaussian form.