Importance of growth direction in mid-infrared quantum cascade lasers
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Issue Date
2014
Authors
Bouzi, Pierre M.
Chiu, YenTing
Deutsch, Christoph
Dikmelik, Yamac
Song, Yu
Tokranov, Vadim
Oktyabrsky, Serge
Gmachl, Claire
Publisher
Journal of Applied Physics
Keywords
growth direction , mid-infrared Quantum Cascade lasers , symmetry , active core , interface roughness , dopant migration , electroluminescence
Abstract
We report on the effect of growth direction on the performance of mid-infrared Quantum Cascade
lasers. The design used has a symmetric active core, capable of operating under both negative and
positive polarities, which allows to test for residual growth asymmetries such as interface roughness
and dopant migration. Calculations of scattering lifetimes from interface roughness and
ionized impurities suggest a dominant contribution from the former, with devices biased positively
averaging ~15% larger broadening and ~50% shorter upper state lifetime than negatively biased
devices. Experimental results for positively biased devices show at least 30% larger broadening
and 35% lower electroluminescence peak intensity than those biased negatively, in good agreement
with the modeling results.