US Patent 7427772 - Periodic nanocrystal LED

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Nanocrystalline based LEDs offer the advantage of higher extraction efficiencies than conventional LEDs but can also have fabrication defects leading to higher resistances and inferior electrical properties. This patent teaches the formation of a periodic nanocrystal structure with fewer defect and less material stress. Claim 1 reads:

1. A semiconductor light emitting device substrate comprised of a single crystal material and having a nanocrystal structure disposed thereon capable of diffracting an electromagnetic wave, wherein a material of the nanocrystal structure is the same as the single crystal material, the nanocrystal structure comprises an etched region and an unetched region, wherein the etched region has a depth of 10-200 nm, and the nanocrystal structure comprises a periodic structure comprising a plurality of crystals with a size of 100-900 nm.