Investigation of the interplay of oxygen presence and Mg addition on InZnO:Al and InZnMgO:Al Thin Films

• Oxygen content tunes carrier concentration and band gap; renormalization dominates. • Oxygen incorporation enhances near-infrared transmittance. • Mg incorporation initially improves carrier mobility; higher levels degrade it. • Optimizing O and Mg is crucial for InZnO:Al/InZnMgO:Al in high-efficiency solar cells. This study investigated the influence of oxygen content and Mg incorporation on the properties of Al-doped Indium Zinc Oxide (IZO:Al) and Al-doped Indium Zinc Magnesium Oxide (IZMO:Al) thin films deposited by radio-frequency sputtering. Increasing oxygen content during sputtering significantly reduced carrier concentration, leading to a redshift in the absorption edge and a narrowing of the optical band gap, primarily attributed to the dominance of the band gap renormalization effect vs the Burstein-Moss effect. Simultaneously, oxygen incorporation enhanced near-infrared transmittance. Mg incorporation initially improved carrier mobility but further increases led to decreased mobility and increased sheet resistance. These findings highlight the complex interplay between oxygen content and Mg incorporation, significantly influencing the electrical and optical properties of IZO:Al and IZMO:Al films. Optimizing these parameters is crucial for achieving a balance of high transparency, low resistivity, and suitable band alignment, essential for their application as transparent conductive oxides in high-efficiency semiconductor devices such as tandem solar cells.