Plasma-Enhanced Atomic Layer Deposition Assisted Low-Temperature Synthetic Routes to Rationally Designed Metastable c-Axis Aligned Hexagonal In-Zn-O

Abstract

Effortsto design and realize exotic metastable phaseswith advancedcharacteristics have been ongoing. However, the challenge lies inidentifying their atomic structures and synthetic routes, as mostexplorations of metastability have relied on intuitions and trial-and-errorapproaches. Here, we present a computational workflow based on densityfunctional theory (DFT) to rationalize the design of metastable materials.We demonstrate that plasma-enhanced atomic layer deposition (PEALD)is a profitable method for synthesizing target material. By screeningthe various hypothetical crystal structures of IZO compounds, we haveidentified the c-axis aligned hexagonal (CAH) In2Zn4O7 as a promising candidate due to its metastabilityand superior electrical properties compared to a binary metal oxidesystem. Remarkably, this metastable phase can be synthesized at asignificant temperature of 200 & DEG;C, compared to the typical crystallizationtemperature of the IZO system. This low-temperature crystallizationis attributed to the distinctive features of PEALD, including tunableatomic order, precise composition control, and adjustable plasma source.By implementing CAH-IZO in thin-film transistor (TFT) applications,we observed desirable characteristics, such as a & mu;FE of 43.4cm(2)/V s, despite the low indium (In) content. We believethat this combined approach of PEALD and computational processingcan expedite the realization of novel metastable materials, with thepotential to expand their applications beyond traditionally exploredmaterials.