Two-dimensional Keldysh theory for non-resonant strong-field ionization of monolayer 2D materials

TL;DR

This paper extends the Keldysh theory to two-dimensional monolayer semiconductors, deriving formulas that account for their unique density of states and validating them with experimental data on MoS2.

Contribution

It introduces a generalized Keldysh theory for 2D materials, providing closed-form and asymptotic formulas specific to monolayer semiconductors with validation against experiments.

Findings

Derived formulas show different behaviors from bulk materials due to 2D density of states.

Validated the theoretical formulas with experimental data on monolayer MoS2.

The work enables better understanding of intense light interaction with 2D materials.

Abstract

The Keldysh theory of photoionization for solids is generalized to atomically thin two-dimensional semiconductors. We derive a closed-form formula and its asymptotic forms for a two-band model with a Kane dispersion. These formulas exhibit characteristically different behaviors from their bulk counterparts which are attributed to the scaling of the 2D density of states. We validate our formulas by comparing them to recent strong-field ionization experiments in monolayer MoS2 with good agreement. Our work is expected to find a wide range of applications in intense light - 2D material interaction.