Effect of oxygen plasma treatment on nonalloyed Al/Ti-based contact for high power InGaN/GaN vertical light-emitting diodes

InGaN/GaN vertical light emitting diodes (LEDs) with argon (Ar) and oxygen (O-2) plasma-treated nonalloyed Al/Ti electrodes were fabricated on sapphire substrates. At the operating current of 350 mA, the forward voltage (V-F) for O-2 plasma-treated Al/Ti-based devices with dimensions 1360 x 1360 mu m(2) was improved, whose value was comparable or lower to that of nonalloyed Cr/Au-based devices. The Al/Ti electrodes resulted in improvement in optical output power of LEDs due to their high reflectivity (typically 10%-15% higher based on our data) compared to LEDs with conventional Cr/Au-based electrodes. The x-ray photoelectron spectroscopy showed the increase in Ga-O peak intensity during O-2 plasma treatment. These results demonstrate that O-2 plasma-treated Al/Ti electrodes reduced the contact resistance by forming a thin conductive GaOxN1-x layer at n-GaN surface. (C) 2013 American Vacuum Society. [http://dx.doi.org/10.1116/1.4773006]