Multiposition Controllable Gate WS2/MoS2 Heterojunction Phototransistor and Its Applications in Optoelectronic Logic Operation and Emulation of Neurotransmission.

Better control of the channel is crucial to improve the performance of existing electron devices. A phototransistor with a specifically designed dual‐gate structure based on a vertical van der Waals heterojunction of WS2 and MoS2 is proposed. The top gate modulates the carrier transport in WS2 at the top of the heterojunction, whereas the back gate can simultaneously control the carrier transport in both MoS2 and WS2 regions located on either side of the heterojunction. Therefore, the rectification ratio of the WS2/MoS2 heterojunction can be modified from approximately 1 to above 104. A very low subthreshold swing of 47 mV dec−1 is obtained. Optoelectronic characterization shows that the responsivity and detectivity are as high as 167.8 A W−1 and 5.8 × 1012 Jones at 532 nm, respectively, which are attributed to the combined modulation effect of the WS2/MoS2 heterojunction and additional homojunction in WS2. Moreover, a logic operation between electronic and optical signals can be performed by utilizing only one multiposition controllable gate phototransistor. In addition, the capability of this dual‐gate phototransistor to emulate information transmission in neuromorphic architectures is presented. These results demonstrate the potential of this approach for the development of next‐generation optoelectronic devices. [ABSTRACT FROM AUTHOR]