Relaxed InGaN engineered substrates with lattice parameter of 3,205A and beyond enabling direct emission at 630nm

Micro displays targeting virtual and augmented reality applications require pixel size in the range of
$10\times 10\mu \mathrm{m}$
or below. Having InGaN based LEDs to emit directly over the full red-green-blue (RGB) spectrum would enable a cost effective transfer and integration. Green and red InGaN based LEDs initially suffer from low internal quantum efficiencies (IQE) and external quantum efficiencies (EQE) as compared to blue LEDs. One solution could be to reduce the strain in the overall structure thanks to an InGaN pseudo-substrate. The Smart Cut™technology enables the layer transfer and strain relaxation of patterned InGaN films. Pattern size can extend from
$10\mu \mathrm{m}$
up to 1mm. This process is today available on 100mm and is being transferred to 150mm wafers. According to the In content of the donor InGaN layer, the a (in-plane) lattice parameter can be tuned up to 3.219A. Full InGaN LED containing InGaN/InGaN multiple quantum wells structures are grown by metalorganic vapor phase epitaxy (MOVPE) on this engineered substrate with a lattice parameter of 3.205A. Long wavelengths have been reached, up to 630nm with FWHM of 48nm at 0.8 A/cm
²
, thanks to the reduced strain in the overall structure which enables a higher In incorporation during the growth.