Atomic composition, structure, and electrical properties of In1-xGaxSb films deposited by magnetron sputtering

This article reports the formation of polycrystalline In1-xGaxSb films (x = 0, 0.2, 0.4, 0.5, and 1) deposited by magnetron sputtering on SiO2/Si substrates and a comprehensive characterization of their atomic composition, structure, and electrical properties. The structural and electrical characteristics of the films can be easily tuned by varying the stoichiometry of the compounds. The atomic composition of the films was investigated with particle induced x-ray emission and Rutherford backscattering spectrometry (RBS) techniques (the latter as a function of depth), while grazing incidence x-ray diffraction analysis yielded valuable information about the structure of the films. In1-xGaxSb films were polycrystalline, with crystallite sizes in the range 18-42 nm. Combining RBS and scanning electron microscopy results, it was possible to infer the overall density and also the density of the crystalline portion of the films, which turned out to be significantly distinct. A non-negligible fraction of oxygen atoms has been detected in all films, most prominently in the ternary ones, contributing to the formation of high density amorphous In2O3 and Ga2O3 in films with 40% and 50% Ga, while amorphous antimony oxide phases are predominant in the binaries as well as the ternary compound with 20% Ga. The electrical characterization of the films was performed using four point and Hall effect methods and the results show a consistent increase in resistivity with Ga concentration.