Probing n-ZnMgO/p-Si nanowire junctions: Insights into composition, strain, and defects via Raman spectroscopy and electrical measurements

Abstract

This article focuses on investigating physical properties of n-ZnMgO/p-Si heterojunctions containing ZnMgO nanowires (NWs) with ZnMgO/ZnO/ZnMgO quantum wells (QWs) grown by molecular beam epitaxy. Detailed analysis of chemical composition, crystal lattice strain, and defects in the structures was conducted via Raman spectroscopy, deep level transient spectroscopy (DLTS), and capacitance-versus-temperature characteristics, C(T). Additionally, current-voltage (I-V) curves were included to demonstrate the rectifying properties of the studied n-ZnMgO/p-Si NW junctions. The samples varied in the thicknesses of the ZnO QWs and the ZnMgO barriers. Raman spectra provided information on strain within the crystal lattice of the nanowires. The values of the biaxial in-plane strain were calculated for the selected samples, and the origin of this strain was discussed in detail. A broadened part of spectrum in the range of 480-600 cm^-1 was ascribed to the contribution of $A_1\left(\mathit{LO}\right)$ mode, which is associated with lattice defects such as oxygen vacancies, zinc interstitials, or their complexes. The presence of deep traps in the junctions was revealed by the DLTS method. Measurements of C(T) characteristics of the p-n junctions disclosed the presence of deep-level traps in the structures as well.