Epitaxial growth optimization, measurement and theoretical analysis of strain-compensated QCL grown on (511)A InP

TL;DR

This paper investigates the growth, measurement, and analysis of strain-compensated quantum cascade lasers on (511)A InP, highlighting the importance of growth conditions and impurity effects on device performance.

Contribution

It presents the first lasing device on (511)A InP with detailed growth optimization and theoretical analysis of impurity scattering effects.

Findings

Optimized arsenic flux and III/V ratio improve material quality.

First lasing device achieved with specific threshold and efficiency.

Observed 7% redshift linked to impurity scattering along (111) direction.

Abstract

Interface roughness scattering is an important limiting factor for achieving high performance Quantum Cascade Lasers. Following recent results, we study the growth conditions for a strain-compensated QCL emitting around 4.6 {\mu}m grown on a (511)A InP substrate using AFM and XRD measurements. We find that modulating the arsenic flux and correctly tailoring the III/V ratio is fundamental to achieve a good quality material. We report the first lasing device on such a platform with a current density threshold of 1.34 kA/cm2 and a slope efficiency of 1.1 W/A, which result suboptimal compared to the (100) reference. Finally, we find a 7% redshift of the (511)A spectrum which we attribute to an impurity scattering due to the increased incorporation along the exposed (111) direction. We validate this statement by verifying that the change in CBO and effective electron mass due to strain along a non-trivial direction cannot cause such a shift by using the k-p method generalized to arbitrary growth directions