Emission enhancement with epitaxially integrated plasmonic materials and Auger recombination mediation through strain




Briggs, Andrew Frederick

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There exists significant interest in the demonstration and development of alternative mid-infrared emitters, with future applications for thermal scene projection, low-cost infrared sensing, and possible long-wavelength quantum communication applications. We propose two approaches for enhancing mid-infrared emitters. The first is an investigation into the parasitic Auger recombination in mid-infrared type-I laser material. Below 3 µm type-I diode lasers have comparable performance to their QCL and ICL counterparts. As bandgap narrows and emission wavelength moves further into the mid-infrared, Auger recombination begins to severely diminish device performance. Improvements in laser performance have been reported in highly strained GaInAsSb active regions, presumed to be due to a suppression in Auger recombination. We focused on differentiating between the effects changes in alloy composition and changes in external strain have on Auger recombination in GaInAsSb and found that within the non-degenerate regime a suppression of Auger recombination was closely linked to the active region chemical composition rather than the strain. The second approach is to enhance type-II mid-infrared emitters by pairing them with monolithically integrated plasmonic materials in an all-epitaxial approach. Remarkable systems have been reported recently using polylithic integration of semiconductor optoelectronic devices and plasmonic materials. Molecular beam epitaxy allows for the all-epitaxial integration of low-loss “designer metals” and relatively inefficient mid-infrared emitters. Coupling plasmonic materials and emitters not only offers a chance to investigate fundamental light-matter interactions but also offers an opportunity to engineer a new class of increase efficiency mid-infrared electrically injected emitters. Through careful optimization of device design, growth, and fabrication we have been able to seamlessly integrates designer plasmonic materials into a quantum dot light-emitting diode. The cavity-enhanced device shows a 5.6 x enhancement over an otherwise identical control sample. Further optimization to overlap the emitter and plasmonic material will lead to an all-epitaxial plasmonically enhanced light-emitting diode. Our approaches include the incorporation of an engineered plasmonic cavity, AlInAsSb digital alloy barrier, and well-overlapped plasmonic n⁺⁺InAs and n⁺⁺InAs/InAsSb T2SL material with type-II quantum emitters to produce both a resonant cavity and plasmonic responses.



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