To enhance light extraction from a blue semipolar (1011) multiple-quantum-well light emitting diode (LED), surface patterning was performed on the backside of a GaN substrate on which LED epitaxial layers had previously been grown. After circular photoresist etching masks were defined, the surface was patterned with conical features by inductively-coupled plasma (ICP) etching. A substantial increase (100% before packaging and 33% after) in output power was observed in comparison with a reference sample which had a smooth backside at a drive current of 20 mA. Since ICP etching is a non-equilibrium process, this technique can potentially be applied to LEDs grown on nonpolar m - or a -plane GaN substrates.
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Zhong et al. (2009) studied this question.
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