Original version
PHYSICAL REVIEW MATERIALS. 2023, 7 (9):094603, DOI: https://doi.org/10.1103/PhysRevMaterials.7.094603
Abstract
Structural, morphological, and optical properties of (In1−xGax)2O3 thin films are reported as a function of the cation composition. A material library with 0.1≤x≤0.64 was fabricated by discrete combinatorial synthesis on r-plane sapphire substrates using pulsed laser deposition. The samples crystallize in the cubic bixbyite phase for x≤0.35. The lattice constant and absorption edge energy systematically decrease and increase, respectively, with increasing Ga content up to x=0.2. For higher Ga admixtures, both saturate. In addition, a significant change in surface morphology occurs at x∼0.2. Transmission electron microscopy examinations of selected samples show a homogeneous incorporation of Ga2O3 into cubic In2O3 for x=0.11, while a segregation of Ga-rich and In-rich regions can be seen for x=0.22 and x=0.35. In the sample with x=0.35, the Ga-rich regions exhibit a preferred orientation with an angle of 45∘–55∘ with respect to the substrate normal, which has been shown to result from a correspondingly faceted In-rich bixbyite layer at the substrate–thin film interface.