Passivated Interfacial Traps of Monolayer MoS2 with Bipolar Electrical Pulse

Heterogeneous integration of monolayers is an emergent route of spatially combining materials with available platforms for unprecedented properties. A long-standing challenge along this route is to manipulate interfacial configurations of each unit in stacking architecture. A monolayer of transition metal dichalcogenides (TMDs) offers an embodiment of studying interface engineering of integrated systems because optoelectronic performances generally trade off with each other due to interfacial trap states. While ultrahigh photoresponsivity of TMDs phototransistors has been realized, a long response time commonly appears and hinders applications. Here, fundamental processes in excitation and relaxation of the photoresponse are studied and correlated with interfacial traps of the monolayer MoS2. A mechanism for the onset of saturation photocurrent and the reset behavior in the monolayer photodetector is illustrated based on device performances. Electrostatic passivation of interfacial traps is achieved with the bipolar gate pulse and significantly reduces the response time for photocurrent to reach saturated states. This work paves the way toward fast-speed and ultrahigh gain devices of stacked two-dimensional monolayers.

Automated summary

Heterogeneous integration of monolayers is an effective approach to combine materials with available platforms for unprecedented properties. The challenge lies in manipulating interfacial configurations in stacking architecture. This study focuses on the interfacial traps of monolayer MoS2 and illustrates a mechanism for the onset of saturation photocurrent and the reset behavior in the monolayer photodetector. The response time for photocurrent can be significantly reduced through electrostatic passivation of interfacial traps, paving the way for fast-speed and ultrahigh gain devices of stacked two-dimensional monolayers.