A novel technique based on the Fresnel diffraction effect for the fabrication of sub-micron ring structures in InGaN/GaN multi-quantum well structures has been demonstrated. The ring structures have an external diameter of 1.5 m and a wall width of 500 nm. A 1 cm-1 Raman shift has been measured, signifying substantial strain relaxation from the fabricated structure. The 5 nm blue shift observed in the cathodoluminescence spectra can be attributed to band-filling and/or screening of the piezoelectric field. A light emitting diode based on this geometry has been demonstrated.
- sub-micron ring structures