The reproducibility and transferability of a THz quantum cascade laser design between two MBE growth manufacturers’ platforms

We report a comprehensive study into the growth of a 2.9 THz quantum cascade laser structure on two different molecular beam epitaxy manufacturers’ systems; within a single growth campaign and over multiple growth campaigns. Device performance figures are compared from all the lasers grown, demonstrating excellent structure reproducibility, not only between each growth campaign, but also between the two MBE systems; including using different combinations and types of group III effusion cells. A small systematic shift in the emission frequency of ∼0.1 THz between the two systems was observed. The mechanisms behind this small shift in emission frequency were investigated and partly attributed to differences in the flux profiles associated with the type of aluminium effusion cells used and inhomogeneous broadening in the structure, possibly due to interface roughness.