The letter reports a theoretical and experimental study on the device performance of near ultraviolet light-emitting diodes ͑LEDs͒ with quaternary AlInGaN quantum barrier ͑QB͒. The indium mole fraction of AlInGaN QB could be enhanced as we increased the trimethylgallium flow rate. It was found the AlInGaN/InGaN LEDs can reduce forward voltage and improve light output power, compared with conventional GaN QB. By using advanced device simulation, it should be attributed to a reduction in lattice mismatch induced polarization mismatch in the active layer, which results in the suppression of electron overflow.

A photoelectrochemical wet mesa etching ͑WME͒ process was used to fabricate InGaN-based light emitting diodes ͑LEDs͒ as a substitute for the conventional plasma mesa dry etching process. The p-type GaN:Mg layer, InGaN active layer, and n-type GaN:Si layer were etched through a sequential photoelectrochemical oxidation and oxide-removing process to define the mesa region. The higher lateral wet-etching rate ͑ϳ3.4 m/h͒ of the InGaN active layer was observed to form a wider undercut structure which has 42.7% light output power enhancement compared to a conventional LED fabricated with the plasma dry etching process. The reverse current of a WME-LED was suppressed by avoiding plasma damage during the dry mesa etching process.

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