# Spatial Control of Multiphoton Electron Excitations in InAs Nanowires by Varying Crystal Phase and Light Polarization

## TL;DR

This study demonstrates how the crystal phase and light polarization can be used to control multiphoton electron excitations in InAs nanowires, enabling precise nanoscale electron emission for advanced optoelectronic applications.

## Contribution

It introduces a method to selectively induce multiphoton electron emission from different crystal phases of InAs nanowires by varying light polarization, supported by ab-initio calculations and simulations.

## Key findings

- Selective multiphoton emission from WZ and ZB segments achieved
- Anisotropic 2nd and 3rd order multiphoton transitions in WZ InAs
- Electric-field enhancement effects are similar across segments

## Abstract

We demonstrate the control of multiphoton electron excitations in InAs nanowires (NWs) by altering the crystal structure and the light polarization. Using few-cycle, near-infrared laser pulses from an optical parametric chirped-pulse amplification system, we induce multiphoton electron excitations in InAs nanowires with controlled wurtzite (WZ) and zincblende (ZB) segments. With a photoemission electron microscope, we show that we can selectively induce multiphoton electron emission from WZ or ZB segments of the same wire by varying the light polarization. Developing \textit{ab-initio GW} calculations of 1st to 3rd order multiphoton excitations and using finite-difference time-domain simulations, we explain the experimental findings: While the electric-field enhancement due to the semiconductor/vacuum interface has a similar effect for all NW segments, the 2nd and 3rd order multiphoton transitions in the band structure of WZ InAs are highly anisotropic, in contrast to ZB InAs. As the crystal phase of NWs can be precisely and reliably tailored, our findings opens up for new semiconductor optoelectronics with controllable nanoscale emission of electrons through vacuum or dielectric barriers.