In a paper titled "Waveguide-coupled nanopillar metal-cavity light-emitting diodes on silicon" just published in Nature Communications, researchers from the Eindhoven University of Technology demonstrated a nano-scale III–V LED layer stack bonded to a silicon substrate and coupled to an InP-membrane waveguide leading to a grating coupler.
Taking the shape of a sub-micron sized nano-pillar, the nano-LED was characterized to be 1000 times more efficient than its predecessors, with an output power in the order of a few nW at room temperature, compared to outputs in pW reported in literature. According to the paper, the device showed a relatively high on-chip external quantum efficiency (10 −4 to 10 −2 for room-temperature and 9.5 K, respectively).
At low temperature, the researchers reported a power level above 50nW, corresponding to over 400 photons per bit at 1Gb/s, "far above the shot-noise limited sensitivity of an ideal receiver", they wrote. Working at telecommunications wavelengths (1.55 μm), the device was successfully modulated using a pulse pattern generator at frequencies up to 5GHz.
"With the expected low loss of short-distance interconnects and continuous progress in integrated receivers, this power level may enable intrachip data communications with an ultracompact source", they note.
The researchers have also developed a surface passivation method that could further boost the efficiency of the nano-LED 100-fold, while energy consumption could be further reduced by improving the ohmic contacts.
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