Optical and electrical properties of highly ordered α-, γ- and α plus γ-MnS films deposited by reactive sputtering technique

In this article, we have studied the detailed electrical and optical characteristics of crystalline alpha(-), gamma(-), and alpha + gamma-manganese sulfide (MnS) thin films. Highly ordered thin films of alpha(-), gamma(-)(,) and alpha + gamma-MnS were prepared by direct current reactive sputtering on glass substrates at different substrate temperatures (room temperature to 400 degrees C) while maintaining other parameters at optimized values. The X-ray diffraction measurement revealed the synthesis of gamma(-), alpha+gamma(-), and alpha-phase of MnS thin films with preferred orientations (002), (002) + (200), and (200), respectively. The morphological and topographical results demonstrated that the particle size as well as the average roughness of MnS samples varied as a linear function of the substrate temperature. The x-ray photoelectron spectroscopy study revealed that the gamma-MnS sample prepared at room temperature has the lowest oxygen related vacancy (12.7%). The optical characteristics such as refractive index n, extinction coefficient k, and optical bandgap E-g are determined in the broad wavelength range of 246-688 nm using spectroscopic ellipsometry. Moreover, the nonlinear refractive index n(2) and the third-order nonlinear optical susceptibility chi((3)) are determined using the Tichy-Ticha relation and Wemple-Didomenico parameters. The ratio of the carrier concentration to the effective mass N/m* has also been determined, indicating best electrical properties for gamma-MnS films. The current research on the optical and electrical properties of highly ordered alpha(-), gamma(-), and alpha + gamma-MnS thin films is expected to have a significant impact on advanced optoelectronic, photonic, and energy applications. Published under license by AIP Publishing.