High-Mobility MoS2 Directly Grown on Polymer Substrate with Kinetics-Controlled Metal-Organic Chemical Vapor Deposition

Abstract

Batch growth of high-mobility (mu(FE) > 10 cm(2)V(-1)s(-1)) molybdenum disulfide (MoS2) films can be achieved by means of the chemical vapor deposition (CVD) method at high temperatures (>500 degrees C) on rigid substrates. Although high-temperature growth guarantees film quality, time- and cost-consuming transfer processes are required to fabricate flexible devices. In contrast, low-temperature approaches (<250 degrees C) for direct growth on polymer substrates have thus far achieved film growth with limited spatial homogeneity and electrical performance (mu(FE) is unreported). The growth of a high-mobility MoS2 film directly on a polymer substrate remains challenging. In this study, a novel low-temperature (250 degrees C) process to successfully overcome this challenge by kinetics-controlled metal-organic CVD (MOCVD) is proposed. Low-temperature MOCVD was achieved by maintaining the flux of an alkali-metal catalyst constant during the process; furthermore, MoS2 was directly synthesized on a polyimide (PI) substrate. The as-grown film exhibits a 4 in. wafer-scale uniformity, field-effect mobility of 10 cm(2)V(-1)s(-1), and on/off ratio of 10(5), which are comparable with those of high-temperature-grown MoS2. The directly fabricated flexible MoS2 field-effect transistors demonstrate excellent stability of electrical properties following a 1000 cycle bending test with a 1 mm radius.