Simulating terahertz quantum cascade lasers: Trends from samples from different labs

TL;DR

This paper compares simulated and experimental results of terahertz quantum cascade lasers across multiple labs, highlighting reproducibility issues and the limited impact of interface roughness on peak current discrepancies.

Contribution

It systematically analyzes the reproducibility of quantum cascade laser performance across different laboratories using a unified simulation approach.

Findings

Discrepancies between measured and calculated peak currents are similar within device groups.

Differences in interface roughness have minimal effect on peak current under lasing conditions.

Reproducibility issues are partly due to fabrication differences across labs.

Abstract

We present a systematic comparison of the results from our non-equilibrium Green's function formalism with a large number of AlGaAs-GaAs terahertz quantum cascade lasers previously published in the literature. Employing identical material and simulation parameters for all samples, we observe that discrepancies between measured and calculated peak currents are similar for samples from a given group. This suggests that the differences between experiment and theory are partly due to a lacking reproducibility for devices fabricated at different laboratories. Varying the interface roughness height for different devices, we find that the peak current under lasing operation hardly changes, so that differences in interface quality appear not to be the sole reason for the lacking reproducibility.