Controlling conduction band alignment and carrier concentration in gallium-doped magnesium zinc oxide by reactive cosputtering

Gallium-doped magnesium zinc oxide (GMZO) holds promise as a UV transparent conducting oxide with tunable bandgap and conductivity, though there has been relatively limited exploration of the broad compositional space available. Conductive GMZO films were deposited by reactive cosputtering at room temperature followed by annealing. The contributions of alloying and the Burstein–Moss effect to the optical bandgap were decoupled through comparisons of as-deposited and annealed films. Compositional analysis in conjunction with electrical characterization was used to quantify the activation of Ga doping in MZO. Combinatorial synthesis was used to explore the optoelectronic performance over a broad composition space. Reactive cosputtering can be used to tailor GMZO properties for optoelectronic applications over a wide range of bandgaps (3.3–4 eV) and resistivity (10−3–>100 Ω cm) through appropriate control of the Mg/Zn ratio and Ga content, respectively.