Orbital gating driven by giant Stark effect in tunneling phototransistors.

Conventional gating in transistors uses electric fields through external dielectrics that require complex fabrication processes. Various optoelectronic devices deploy photogating by electric fields from trapped charges in neighbor nanoparticles or dielectrics under light illumination. We demonstrate orbital gating driven by giant Stark effect in tunneling phototransistors based on 2H-MoTe2 without using external gating bias or slow charge trapping dynamics in photogating. The original self-gating by light illumination modulates the interlayer potential gradient by switching on and off the giant Stark effect where the dz 2-orbitals of molybdenum atoms play the dominant role. The orbital gating shifts the electronic bands of the top atomic layer of the MoTe2 by up to 100 meV, which is equivalent to modulation of a carrier density of 7.3×1011 cm-2 by electrical gating. Suppressing conventional photoconductivity, the orbital gating in tunneling phototransistors achieves low dark current, practical photo-responsivity (3357 AW-1 ), and fast switching time (0.5 ms) simultaneously. This article is protected by copyright. All rights reserved.