Interface engineering of ferroelectric-gated MoS2 phototransistor

Abstract

Two-dimensional (2D) layered materials have received significant attention owing to their unique crystal structures as well as outstanding optical and electric properties in photoelectric detection. However, most 2D materials are very sensitive to the environment. Adsorbates and traps introduced during the preparation process have a negative effect on the performance of devices based on these materials. Here, we focus on a molybdenum disulfide (MoS 2 ) phototransistor gated by ferroelectrics, and insert a hexagonal boron nitride (h-BN) layer between MoS 2 and the ferroelectric film to improve the interface. To clarify the role of h-BN in this device, two parallel devices are prepared on the same MoS 2 flake. One device is covered with h-BN, while the other is in direct contact with the ferroelectric film. The electronic and optoelectronic properties of these two devices are then measured and compared. Experimental results reveal that, compared to device without h-BN, the MoS 2 phototransistor with h-BN exhibits higher carrier mobility (average value: 85 cm 2 ·V −1 ·s −1 and highest value: 185 cm 2 ·V −1 ·s −1 ), larger responsivity (85 A·W −1 ), and larger detectivity (1.76 × 10 13 Jones). Thus, this strategy is significant for the interface engineering and performance improvement of devices based on 2D materials.