HE N2 REACTIVE GAS-COMPOSITION AND THE STRUCTURAL AND ELECTRICAL-PROPERTIES OF INN THIN-FILMS GROWN ON ALN-NUCLEATED (00.1) SAPPHIRE BY PLANAR MAGNETRON SPUTTERING/

The effects of He/N2 reactive gas composition on the structural and el ectrical properties of InN thin films deposited by magnetron sputterin g on AlN-nucleated (00.1) sapphire substrates have been investigated. X-ray scattering studies demonstrate that the films are an aggregate o f strained heteroepitaxial domains and highly relaxed textured domains and that their apportionment is strongly tied to the reactive gas com position. The sputtering rate, as evidenced by film thickness, nominal ly increases with increasing volume fraction of N2, but enhanced growt h and epitaxial volume are observed at concentrations of N2 near 60%. The variation in electrical transport properties with increasing N2 fr action in the gas mixture is smoother, with the n-type Hall mobility r ising monotonically from 35 cm2 V-1 s-1 for films deposited in a 30% N 2 volume fraction to 55 cm2 V-1 s-1 for growth in pure N2, largely due to an increase in the volume of heteroepitaxial domains, the conseque nt reduction in the density of high-angle grain boundaries, and the re sulting decrease in intergrain resistance and film resistivity.