Effective Mg Incorporation in CdMgO Alloy on Quartz Substrate Grown by Plasma-assisted MBE

TL;DR

This study successfully grew single-phase CdMgO alloys with varying Mg content on quartz using plasma-assisted MBE, analyzing their structural, elemental, morphological, and optical properties, revealing tunable bandgaps and disorder levels.

Contribution

It demonstrates the controlled growth of single-phase CdMgO alloys with tunable optical properties via plasma-assisted MBE on quartz substrates.

Findings

Optical bandgap increases from 2.34 eV to 3.47 eV with Mg content.

Single cubic phase confirmed across all compositions.

Urbach energy increases, indicating more disorder with higher Mg incorporation.

Abstract

The development of CdMgO ternary alloy with a single cubic phase is challenging but meaningful work for technological advancement. In this work, we have grown a series of Cd1-xMgxO ternary random alloys with various Mg concentrations (x = 0, 30, 32, 45, and 55%) on quartz substrate by plasma-assisted molecular beam epitaxy (PA-MBE) technique. The structural investigations of alloys were performed using the X-ray diffraction (XRD) technique. The decreases in average crystallite size and lattice parameters were observed with an increase in Mg content in the alloys. XRD analysis confirms a single cubic phase is obtained for alloy compositions. The elemental and morphological studies were carried out using energy dispersive x-ray (EDX) spectroscopy and atomic force microscope (AFM) technique, respectively. The optical investigation was carried out using UV-Vis spectroscopy. The optical bandgaps were estimated using the Tauc relation and it was varied from 2.34 eV to 3.47 eV by varying the Mg content from zero to 55% in the alloys. The Urbach energy increases from 112 meV to 350 meV which suggests a more disordered localized state with an increase in Mg incorporation in the alloys.