Effect of film thickness on the surface, structural and electrical properties of InAlN films prepared by reactive co-sputtering

Abstract

InAlN films of different thicknesses (150nm, 250nm, 380nm, 750nm and 1050nm) were grown on Si (111) by means of reactive co-sputtering at 300°C. Surface morphology results indicated an increase in the grains size and their spacing with increase of the film thickness. The surface of InAlN remained smooth with a slight variation in its RMS roughness from 1.29nm to 6.62nm by varying the film thickness. X-ray diffraction patterns exhibited InAlN diffraction peaks with preferred orientation along (002) plane in the thickness range 250nm to 750nm, however, the preferred orientation of the film was changed towards (101) plane at 1050nm. An improvement in the crystallinity of InAlN was observed with increase of the film thickness. Electrical characterization revealed a decrease in the film's resistivity by increasing its thickness to 750nm, however, the resistivity was found to increase at 1050nm. The electron concentration indicated an increasing trend whereas changes in the electron mobility were found to be inconsistent with increase of the film thickness.