Optical and Electrical Properties of ZnMgO with High Mg Content Elaborated by Ultrasonic Spray Pyrolysis Using Water‐Based Solutions

ZnMgO thin films are elaborated by ultrasonic spray pyrolysis using water‐based solutions only, for an Mg composition as high as 70 mol%. The elaboration conditions are optimized and the structural, optical, and electrical properties of the ZnMgO films are investigated with respect to the Mg concentration using X‐Ray fluorescence, X‐Ray diffraction, atomic force microscopy, Raman and transmission spectroscopies, and van der Pauw/Hall effect electrical measurements. The obtained properties are correlated to analyze the miscibility and, for single‐phase material, the optoelectronic, optical, and transport properties with respect to the composition. The elaborated thin films exhibit a monotonous increase in the bandgap, a high transparency above 90% in the visible region, and a dramatic decrease in the n‐type carrier concentration, for Mg compositions lower than 30 mol% where wurtzite single‐phase structure is evidenced. A compensation mechanism of the n‐type dopants in ZnO, attributed to interstitial Zn which acts as a shallow donor, is given as an explanation of this variation of the carrier concentration. These optoelectronic properties show that ZnMgO can be efficiently used in applications such as UV detectors and solar cells. The optimized elaboration of ZnMgO was performed using ultrasonic spray pyrolysis with Mg miscibility of 30%. The transmission of the ZnMgO films was above 90%. The carrier concentration decreases due to the bandgap modulation from 3.26 to 3.65 eV and inhibition of shallow donors. The ZnMgO properties can be exploited for detectors and all‐oxide solar cells.