Filling LEDs' green gap with dodecagonal-faced wurtzite nanowires

May 16, 2018 //By Julien Happich
Filling LEDs' green gap with dodecagonal-faced wurtzite nanowires
Aiming to fill what's currently known as the “green gap” in the LED industry, researchers from Eindhoven University of Technology have explored various aluminium indium phosphide nanowire growth compositions, obtaining high-crystal quality wurtzite nanowires whose light emission they could tune based on their inner composition. 

In a paper titled "Efficient Green Emission from Wurtzite AlxIn1–xP Nanowires" published in ACS' Nano Letters, the researchers share their findings as they grew WZ AlxIn1–xP nanowires with high crystal quality on a nanoimprint-patterned (111)A InP substrate. The catalyst-free growth of the nanowires was performed through selective area metalorganic vapor phase epitaxy (SA-MOVPE), using a 50nm silicon nitride mask with a square array of 150nm diameter holes at a 512nm pitch. The researchers found that carefully controlling the V/III material ratio during SA-MOVPE growth was key to achieve high crystal purity and avoid the parasitic growth on the SiNx layer.

What's more, they studied the morphologies and photoluminescence spectrum of different nanowire growth compositions, yielding differently faceted geometries from hexagonal for InP wurtzite nanowires to dodecagonal for Al0.25In0.75P nanowires. Doing so, they demonstrated a tunable direct band gap room-temperature light emission from the infrared range at 875nm (1.42 eV) to the green range at 555nm (2.23 eV). 

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