Hydrogen-Assisted Growth of Ultrathin Te Flakes with Giant Gate-Dependent Photoresponse

Tellurium (Te), as an elementary material, has attracted intense attention due to its potentially novel properties. However, it is still a great challenge to realize high-quality 2D Te due to its helical chain structure. Here, ultrathin Te flakes (5 nm) are synthesized via hydrogen-assisted chemical vapor deposition method. The density functional theory calculations and experiments confirm the growth mechanism, which can be ascribed to the formation of volatile intermediates increasing vapor pressure of the source and promoting the reaction. Impressively, the Te flake-based transistor shows high on/off ratio approximate to 10(4), ultralow off-state current approximate to 8 x 10(-13) A, as well as a negligible hysteresis due to reducing thermally activated defects at 80 K. Moreover, Te-flake-based phototransistor demonstrates giant gate-dependent photoresponse: when gate voltage varies from -70 to 70 V, I-on/I-off is increased by approximate to 40-fold. The hydrogen-assisted strategy may provide a new approach for synthesizing other high quality 2D elementary materials.