Fig. 2: Bandgap closing and insulator to metal transition in 2D Te under pressure.
From: High-pressure induced Weyl semimetal phase in 2D Tellurium
a The longitudinal resistance (Rzz) as a function of back-gate voltage Vg at different pressures from 0 GPa to 2.47 GPa. The temperature is 1.5 K. b Schematic band diagram of 2D Te field-effect transistor in a differential conductance (dI/dV) measurement setup at 0 GPa and 2.47 GPa. The current dI is determined by the dc bias voltage Vb, the small ac excitation dV, and the gate voltage Vg. c Back-gate voltage Vg dependence of the differential conductance (dI/dV) at Vb = 0 V. The temperature is 1.5 K and the ac excitation dV is 1 μV. Over 3 orders of magnitude difference in conductance minima at low temperature indicates the bandgap is closed in 2D Te under high pressure (2.47 GPa). d Temperature dependence of the normalized longitudinal resistance (Rzz(T)/Rzz(150 K)) at different pressures. The insulator-to-metal transition is observed. e Temperature dependence of the longitudinal resistance (Rzz) at Vg = −20 V and Vg = 40 V. Both electrons and holes have metallic behavior at high pressure (2.47 GPa).
