Wafer-Scale Two-Dimensional Molybdenum Diselenide Phototransistor Array via Liquid-Precursor-Assisted Chemical Vapor Deposition

Abstract

Monolayer transition metal dichalcogenides (TMDs) have received considerable interest as a candidate material for ultrathin photodetectors, but their practical applications are hindered by difficulties in synthesizing high-quality films over centimeter-scale areas. Although chemical vapor deposition (CVD) based on liquid-phase precursors has shown promise for large-area synthesis of TMDs, the resulting films typically exhibit much lower optoelectronic performance due to the lack of wafer-scale uniformity with monolayer thickness and inferior electrical properties induced by defects. In this article, the authors present a wafer-scale, gate-tunable photodetector array from high-quality monolayer molybdenum diselenide (MoSe2) films synthesized with the liquid-phase CVD process assisted by a growth promoter. Continuous monolayer MoSe2 can form by introducing potassium iodide as a growth promoter for selenizing the metal-precursor film. Side-by-side comparison between MoSe2 formed with and without the potassium iodide reveal that the promoter-assisted growth strategy significantly improves the crystallinity, which results in enhanced optoelectronic properties. The resulting photodetector array is highly photosensitive over the visible wavelengths with photoresponsivities higher than those of the previously reported devices based on CVD-synthesized monolayer TMDs and even comparable to the devices fabricated from mechanical exfoliation approach.