Carrier dynamics in ion-implanted GaAs studied by simulation and observation of terahertz emission

TL;DR

This study combines experimental and simulation approaches to investigate how ion implantation-induced defects in GaAs influence terahertz emission, revealing that increased vacancy concentration and faster carrier trapping shorten THz pulses.

Contribution

It provides a detailed simulation model that explains the impact of ion-induced damage on THz emission in GaAs, integrating experimental data with carrier dynamics modeling.

Findings

Higher ion doses increase THz peak frequency from 1.4 to 2.2 THz.

Increased vacancy concentration shortens THz pulses.

Carrier trapping time significantly affects THz emission characteristics.

Abstract

We have studied terahertz (THz) emission from arsenic-ion implanted GaAs both experimentally and using a three-dimensional carrier dynamics simulation. A uniform density of vacancies was formed over the optical absorption depth of bulk GaAs samples by performing multi-energy implantations of arsenic ions (1 and 2.4MeV) and subsequent thermal annealing. In a series of THz emission experiments the frequency of peak THz power was found to increase significantly from 1.4 to 2.2THz when the ion implantation dose was increased from 10^13 to 10^16 cm-3. We used a semi-classical Monte-Carlo simulation of ultra-fast carrier dynamics to reproduce and explain these results. The effect of the ion-induced damage was included in the simulation by considering carrier scattering at neutral and charged impurities, as well as carrier trapping at defect sites. Higher vacancy concentrations and shorter carrier trapping times both contributed to shorter simulated THz pulses, the latter being more important over experimentally realistic parameter ranges.