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HL: Fachverband Halbleiterphysik

HL 13: Poster I

HL 13.29: Poster

Montag, 18. März 2024, 15:00–18:00, Poster E

Cation segregation in an (In,Ga)₂O₃ thin film library beyond the miscibility limit of the bixbyite structure — •Sandra Montag¹, Daniel Splith¹, Max Kneiß¹, Marius Grundmann¹, Javier Garcia Fernandez², Øystein Prytz², and Holger von Wenckstern^1,2 — ¹Felix Bloch Institute for Solid State Physics, Leipzig University, Germany — ²Department of Physics/Centre for Materials Science and Nanotechnology, University of Oslo, Norway

The transparent semiconductors In₂O₃ and Ga₂O₃ crystallise in different polymorphs. Hence, a phase change occurs in the alloy system of (In_1−xGa_x)₂O₃, grown in bixbyite cubic structure at low x. To observe this change, a material library of thin films 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 bixbyite phase for x ≤ 0.35, as revealed by X-ray diffraction. However, lattice constant and absorption edge energy systematically decrease and increase, respectively, with increasing Ga content only 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 higher x. In a sample with x = 0.35, the Ga-rich regions exhibit a preferred orientation, which has been shown to result from a correspondingly faceted In-rich bixbyite layer at the substrate-thin film interface.

Keywords: In2O3; Ga2O3; alloys; PLD; TEM