Researchers grow efficient InGaN LEDs for green and red

May 07, 2019 //By Julien Happich
Researchers grow efficient InGaN LEDs for green and red
Researchers from Lund University, Sweden, have devised a novel method to synthesize arrays of InGaN submicrometer platelets for InGaN LEDs by selective area metalorganic vapour-phase epitaxy (MOVPE), whose indium content they can increase up to 18% while limiting strain.

This allowed them to fabricate highly efficient green and red nitride LEDs without the adverse effects of crystal defects.

Describing their findings in a paper titled ”InGaN Platelets: Synthesis and Applications toward Green and Red Light-Emitting Diodes” published in Nano Letters, the researchers explain that in order to remove the strain detrimental to the optical properties of InGaN quantum wells typically grown on a GaN layer, they used an InGaN buffer layer instead, which they obtained through MOVPE selectively over a GaN tip.

During an annealing step, they were able to etch down the apex of the pyramidally-grown InGaN into a c-oriented InGaN hexagonal platelets just 100 to 200nm thick and about 630nm in diametre. Further growth of a InGaN buffer layer allowed the researchers to increase Indium content into subsequent InGaN Qws.


Synthesizing InGaN platelets and LED structures. (a) InGaN pyramids grown by selective area MOVPE. (b) Bottom InGaN layer with a top c-plane formed by etching down from the pyramid apex. (c) InGaN regrowth to flatten the rough c-plane. (d) InGaN single QW growth on the c-plane of the InGaN platelet templates. (e) Prototype LED structure with p-InGaN grown above the single QW, with definitions of all InGaN layers.

 


Schematic of InGaN platelet LEDs.

 

Using this strategy, the authors were able to prototype QW LEDs grown on such InGaN platelets, emitting green on In 0.09Ga0.91N and red on In 0.18Ga0.82N at room temperature.

The authors have filed IP to protect their technology and this research and development was performed in close relation to two of the university’s spin-outs, namely Glo AB and Hexagem AB, explained Lars Samuelson, Professor Solid State Physics/NanoLund at Lund University.

Lund University - https://lunduniversity.lu.se

 

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