Simulation and optimisation of terahertz emission from InGaAs and InP photoconductive switches

TL;DR

This paper uses a detailed 3D simulation to optimize terahertz emission from InGaAs and InP photoconductive switches, revealing how material properties and trap dynamics influence emission power and bandwidth.

Contribution

It introduces a comprehensive 3D carrier dynamics model for simulating terahertz emission from InGaAs and InP, incorporating bandstructure and dielectric effects for optimization.

Findings

Increased emission power as InGaAs approaches InAs due to higher electron mobility.

Low-temperature growth and ion-implantation affect bandwidth and power via carrier trapping.

Sub-picosecond trapping enhances bandwidth but reduces emission power.

Abstract

We simulate the terahertz emission from laterally-biased InGaAs and InP using a three-dimensional carrier dynamics model in order to optimise the semiconductor material. Incident pump-pulse parameters of current Ti:Sapphire and Er:fibre lasers are chosen, and the simulation models the semiconductor's bandstructure using parabolic Gamma, L and X valleys, and heavy holes. The emitted terahertz radiation is propagated within the semiconductor and into free space using a model based on the Drude-Lorentz dielectric function. As the InGaAs alloy approaches InAs an increase in the emitted power is observed, and this is attributed to a greater electron mobility. Additionally, low-temperature grown and ion-implanted InGaAs are modelled using a finite carrier trapping time. At sub-picosecond trapping times the terahertz bandwidth is found to increase significantly at the cost of a reduced emission power.