Amorphous Oxide Semiconductors: role of disorder and composition in defect formation, carrier generation, and transport properties

Unlike Si-based semiconductors, amorphous oxide semiconductors (AOSs) exhibit optical, electrical, thermal, and mechanical properties that are comparable or even superior to those possessed by their crystalline counterparts. Although amorphous materials lack grain boundaries and periodicity, the electron transport is more complex than in the crystalline phases: strong local distortions in the metal-oxygen polyhedra and intricate structural morphology in AOSs affect carrier mobility via composition, defects, thermal vibrations, nano-crystallinity, and lattice strain. Moreover, given many degrees of freedom in amorphous materials, defects in AOSs have the structural, thermal, and electronic characteristics that differ fundamentally from those in the crystalline transparent conducting oxides.
In this talk, complex deposition-structure-property relationships in several prototype AOSs are discussed. The results of systematic computationally-intensive ab-initio Molecular Dynamics followed by comprehensive structural analysis and accurate density-functional calculations, are integrated with experimental measurements to understand the origins of complex behavior in the disordered materials and to derive versatile design principles for next-generation transparent amorphous semiconductors.