Quantum Trapping on MoS2 through Lifetimes of Resonant Electrons: Revealing Pauli Exclusion Principle

TL;DR

This study reveals how quantum trapping and the Pauli exclusion principle influence electron lifetimes on MoS2, leading to narrower resonance linewidths and insights into surface potential and energy gaps.

Contribution

It demonstrates the impact of quantum trapping on FER linewidths and provides a method to measure band bending using FER energies on MoS2.

Findings

FER linewidth varies with electric field due to quantum trapping

Resonant electron lifetimes are prolonged by Pauli exclusion principle effects

FER linewidths can be as narrow as 12 meV

Abstract

We demonstrate that the linewidth of the field emission resonance (FER) observed on the surface of MoS2 using scanning tunneling microscopy can vary by up to one order of magnitude with an increase in the electric field. This unusual phenomenon originates from quantum trapping, where the electron relaxed from the resonant electron in the FER is momentarily trapped in the potential well on the MoS2 surface. Because the relaxed electron and the resonant electron have the same spin and the action of the Pauli exclusion principle, the lifetimes of the resonant electrons can be substantially prolonged when the relaxed electrons engage in the resonance trapping. The linewidth of the FER is thus shrunk considerably to as narrow as 12 meV. Moreover, it was found that the valley intensities around the FER are zero, indicating that MoS2 has an energy gap above the vacuum level. By using the energies of FERs, the potential of the band bending in the MoS2 interior can be measured precisely.