Finite element modeling of extraordinary optoconductance in GaAs-In metal-semiconductor hybrid structures

TL;DR

This paper models extraordinary optoconductance in GaAs-In hybrid structures using finite element methods, explaining experimental observations and dependencies on laser position, power, and temperature.

Contribution

It introduces a finite element model that accurately reproduces EOC behavior in GaAs-In structures, incorporating carrier mobility, diffusion, and temperature effects without fitting parameters.

Findings

EOC depends on laser position, power, and temperature.

The model fits experimental data well across various conditions.

Bias current produces a linear voltage offset, not affecting EOC.

Abstract

We present a detailed discussion of extraordinary optoconductance (EOC). Experimental data was acquired via macroscopic metal-semiconductor hybrid structures composed of GaAs and In and subjected to illumination from an Ar ion laser. A drift diffusion model using the finite element method (FEM) provided a reasonable fit to the data. EOC is explored as a function of laser position, bias current, laser power density, and temperature. The positional dependence of the voltage is accounted for by the Dember effect, with the model incorporating the excess hole distribution based on the carrier mobility, and thus the mean free path. The bias current is found to produce a linear voltage offset and does not influence the EOC. A linear relationship is found between the laser power density and the voltage in the bare and hybrid devices. This dependence is reproduced in the model by a generation rate parameter which is related to the power density. Incorporating the mobility and diffusion temperature dependence, the model directly parallels the temperature dependence of the EOC without the use of fitting parameters.