Ultrahigh sensitive MoTe2 phototransistors driven by carrier tunneling

Transition metal dichalcogenides (TMDs) demonstrate great potential in electronic and optoelectronic applications. However, the device performance remains limited because of the poor metal contact. Herein, we fabricate a high-performance ultrathin MoTe2 phototransistor. By introducing an electron tunneling mechanism, electron injection from electrode to channel is strikingly enhanced. The electron mobility approaches 25.2 cm2 V−1 s−1, better than that of other back-gated MoTe2 FETs. Through electrical measurements at various temperatures, the electron tunneling mechanism is further confirmed. The MoTe2 phototransistor exhibits very high responsivity up to 2560 A/W which is higher than that of most other TMDs. This work may provide guidance to reduce the contact resistance at metal-semiconductor junction and pave a pathway to develop high-performance optoelectronic devices in the future.