Optoelectronic properties of coexisting InGaZnO4 structures

Abstract

Indium gallium zinc oxides (IGZO) have been developed for thin-film transistor technologies. In this work, we analyze the fundamental properties of crystalline InGaZnO4, considering all possible Ga/Zn atomic distribution patterns. Using the hybrid Hartree-Fock density functional approach, the most stable configurations are identified. The simulations reveal that the considered configurations are indirect band-gap semiconductors with highly dispersive conduction bands (CB) and very flat valence bands (VB). Thereby, the electron effective masses are light, contrary to the heavy hole effective masses. This implies a good electron mobility and suppressed hole mobility, and consequently a low off-state current that minimizes the power consumption in future InGaZnO4-based transistors. Coexistence of different configurations is not an issue for InGaZnO4 since they all present very similar optoelectronic properties.