Ion migration in GaSb/Mn multilayers for memories applications: Study of Mn diffusion into the GaSb layers

Abstract

This work presents a study of bilayer and multilayer systems of GaSb/Mn, obtained via DC magnetron sputtering at room temperature for memories applications. These architectures were observed through HR-SEM, which determined that the GaSb and Mn layers had an average thickness of 186,01±5,582 nm and 10,71±0,323 nm, respectively. Through the deconvolution of AES spectra, it was possible to identify the chemical element concentration profiles for each system and propose a model of diffusion layers. The GaSb/Mn systems were analyzed in two cases; in the cases of Mn deposited on the surface of GaSb wafer and bilayer systems, the Mn diffusion process was studied by the conventional Fick’s second law, considering the Mn layer as a constant source, and the Mn diffusion coefficient values correspond to 1,6×10−15cm2/s and 5,8×10−15cm2/s, respectively. The superposition of Fick´s second law solutions in each section of the multilayer architecture was used to describe the experimental concentration profile. Through, the model proposed to calculate the different diffusion coefficients of Mn layers, the description of the diffusion process in the bilayer and multilayer systems and their correlation with synthesis parameters, such as deposition time, has been satisfactory. In the multilayer architecture case, the Mn diffusion coefficients have been reported, considering the Mn layer position, and their values corresponding are 1,105×10−14cm2/s and 6,5×10−15cm2/s for Mn inner and middle layer respectively. Finally, the resistive behavior of the multilayers was studied through I-V curves. It was possible to establish the bipolar resistive behavior of the multilayer and contribution to the formation of conductive filaments or the space charge limited current like conductive mechanism of the multilayer thin films.