An increase in the performance of amorphous ZnSnO metal-semiconductor-metal UV photodetectors by water vapor annealing

Abstract

Amorphous ZnSnO (a-ZTO) is an alternatives for In-based amorphous metal oxide semiconductors (e.g. a-InGaZnO). However, ZTO-based transistors or photodetectors (PDs) do not perform well because they have superfluous electrons, which come from the oxygen vacancies (Vo). This study proposes a facile method for the synthesis of a high-quality a-ZTO thin film for UV PD applications. When the as-spun precursor is pre-annealed and exposed to saturated water vapor, the hydrolysis process is initiated and the entire reaction is thoroughly completed, so the number of Vo is reduced. Suppressing Vo results in a reduction in the number of residual electrons and recombination centers so the dark current is decreased and photocurrent is increased. A solution-processed ZTO metal-semiconductor-metal PD with an ultra-high photo-to-dark current ratio of 2556 is fabricated.