Thermal Annealing Effect on GaSb Thin Films Deposited on Si (001) for Assembly of GaSb/Mn Multilayer Systems at Room Temperature

Abstract

This work presents a study of the morphological and structural properties of GaSb and GaSb/Mn thin films as support for the construction of GaSb/Mn multilayer systems deposited on Si (001) wafer substrate for electronic and spintronic applications. Thin films were obtained through DC magnetron sputtering, and the GaSb thin film was subjected to high-vacuum annealing for 2 h, 4 h, 6 h, 8 h and 10 h. The morphological properties were studied by SEM micrographs. It was observed that the width of depression regions on the GaSb thin film surface decreased (from ~ 617 nm to ~ 56 nm) when the annealing time was increased. A fast Fourier transform filter allowed identifying the formation of grains on the surface of the sample. The dependence of the grain size on the annealing times was described through the abnormal model. XRD measurements and the Burke-Turnbull model were used for establishing the dependence between GaSb crystallite size and annealing times. From Auger spectra, it was possible to determine the Ga diffusion process, its high mobility in the GaSb matrix, and its relationship with morphological properties. It was observed that the thermal processes favor the GaSb phase formation and the increase of grain size on the surface of the sample. AFM micrographs showed the topographical characteristics of the GaSb thin films surface and MFM images presented an exploration of the magnetic behavior for the bilayer system. Loops in hysteresis at 50 K were observed through measurements of the vibrating sample magnetometer, for the [GaSb/Mn] 3 sample fabricated at room temperature (T s = 300 K). These loops have been attributed to the magnetic anisotropy conditions generate through unbalanced Mn magnetic moments due to the Mn antiferromagnetic property presented at this temperature and the diffuse interfaces between GaSb and Mn layers. Lastly, the study of morphological properties of single-layer GaSb and its dependence on annealing times allowed determining that GaSb/Mn multilayer systems fabricated at room temperature present diffuse interfaces, although with clearly distinguished layers, and represent an alternative option for their fabrication.