Performance enhancement of multilayer MoS2 phototransistors via photoresist encapsulation

We propose the encapsulation of bottom-gate multilayer MoS2 phototransistors with an AZ (R) 5214E photoresist as an effective device design to enhance the optoelectronic properties of the phototransistors. The photoresistencapsulated MoS2 phototransistors, based on mechanically exfoliated MoS2 crystals, exhibited an improved device performance. After the photoresist encapsulation, the responsivity and detectivity of the device increased by seven-fold to 3.2 x 10(3) A W-1 and by five-fold to 2.3 x 10(12) Jones, respectively, under a 650-nm laser with an incident power density of 2.1 mW cm(-2). We attribute the observed enhancement in the phototransistor performance to the enhanced electrical properties owing to the n-type doping via photoresist encapsulation. These results demonstrate that MoS2 phototransistors can achieve high performance without complicated device architecture and process, and thus, photoresist encapsulation presents an effective method for developing highperformance two-dimensional optoelectronic devices.