This work reports on high extraction efficiency in subwavelength GaAs/AlGaAs semiconductor nanopillars. We achieve up to 37-fold enhancement of the photoluminescence (PL) intensity from sub-micrometer (sub-µm) pillars without requiring back reflectors, high-Qdielectric cavities, nor large 2D arrays or plasmonic effects.
This is a result of a large extraction efficiency for nanopillars <500 nm width, estimated in the range of 33-57%, which is much larger than the typical low efficiency (∼2%) of micrometer pillars limited by total internal reflection. Time-resolved PL measurements allow us to estimate the nonradiative surface recombination of fabricated pillars.
We conclusively show that vertical-emitting nanopillar-based LEDs, in the best-case scenario of both reduced surface recombination and efficient light out-coupling, have the potential to achieve notable large external quantum efficiency (∼45%), whereas the efficiency of large µm-pillar planar LEDs, without further methods, saturates at ∼2%. These results offer a versatile method of light management in nanostructures with prospects to improve the performance of optoelectronic devices including nanoscale LEDs, nanolasers, single-photon sources, photodetectors, and solar cells.
The full article can be found here.
Bruno Romeira*, Jérôme Borme, Hélder Fonseca, João Gaspar, and Jana B. Nieder*, Optics Express, Vol. 28, Issue 22, pp. 32302-32315 (2020)
