Crystal growth of CdZnO thin films: a combined numerical and experimental study in a two-inlet horizontal MOCVD reactor

This work presents a combined numerical and experimental study of Cd₁₋ₓZnₓO thin film growth in a two-inlet horizontal MOCVD reactor. A three-dimensional model was used to analyse flow patterns, temperature fields, and precursor transport, enabling a direct comparison between helium and nitrogen as carrier gases. It was determined that helium produces smooth, centrally directed longitudinal flow, higher diffusion coefficients, and more uniform temperature fields, but results in larger film composition variations. In contrast, nitrogen induces longitudinal convective rolls that generate heterogeneous temperature zones, enhanced convective mixing, and a reduced effective boundary-layer thickness, leading to smoother zinc composition gradients at the expense of sharper thickness variations. These trends were experimentally validated through the deposition of CdZnO films on 2-in. r-sapphire substrates and the spatial characterization of their thickness and composition. • Cd₁₋ₓZnₓO films were grown in a two-inlet horizontal MOCVD reactor. • Helium and nitrogen as carrier gases were systematically compared. • Thickness and composition homogeneity were linked to carrier-gas properties. • Combined simulations and experiments revealed the origin of growth non-uniformities. • Results provide guidelines for carrier-gas selection and process optimization.