Device Performance of Nonpolar a-plane (11-20) InGaN/GaN Light Emitting Diode on r-plane Sapphire Substrates

Nonpolar a-plane (11-20) InGaN/GaN light-emitting diodes were successfully demonstrated on r-plane (1-102) sapphire substrates. High-crystalline-quality a-plane (11-20) GaN films with smooth morphologies were obtained by using metalorganic chemical vapor deposition (MOCVD) with a multi-step growth method. No apparent blueshift in the peak emission wavelength was observed over a 150 mA current range from on-wafer measurements, indicating that there is no strong polarization-induced electric field in the a-plane GaN LEDs. The optical output power and the external quantum efficiency were measured as 1.3 mW and 2.55%, respectively, at a driving current of 20 mA when packaged with resin epoxy molding.