# Visualization of Light-Impinging Geometry in Nonlinear Photocurrents of Vertical Optoelectronic Devices

## TL;DR

The paper explains how the geometry of vertical optoelectronic devices affects nonlinear photocurrents and proposes a new way to visualize and redefine light-impinging angles.

## Contribution

The study introduces a visual approach to redefine light-impinging geometry in vertical devices, impacting nonlinear photocurrent behavior.

## Key findings

- Light-impinging geometry in vertical structures requires redefining azimuthal and incidence angles.
- Device geometry affects nonlinear photocurrents, allowing or forbidding them based on illumination.
- The findings enable better use of nonlinear photocurrents in flexible optoelectronic applications.

## Abstract

Nonlinear photocurrents (NPs) are electrical currents expected to be measured at the electrodes of a device consisting of an active area, sensitive to light, with a higher-order in-electric field where light-impinging geometry (LIG) is the determining factor in the experimental observation. Although the phenomenology of this light–matter interaction is clear for light directed on a lateral device plane with well-defined azimuthal and incidence angles, as well as light polarization angle, it can be quite complicated for a vertical device structure and reconsideration of the expected NP contributions is necessary in the latter case. In this study, we used a visual approach to describe the LIG for vertical device structures using a specific example of a photodiode, and showed that these angles must be redefined, namely, the interchangeability of azimuthal and incidence angles. The influence of device geometry-dependent optical illumination is reflected on the behavior of NP; therefore, the NPs that are known to be forbidden in certain LIGs can be allowed and vice versa. These results pave the way for the utilization of NPs in flexible optoelectronic applications.