Blue, green, and amber InGaN/GaN light-emitting diodes on semipolar {1122} GaN bulk substrates

We demonstrate the fabrication of blue, green, and amber InGaN/GaN light-emitting diodes (LEDs) on semipolar {11 (2) over bar2} bulk GaN substrates. The {11 (2) over tilde2} GaN substrates used in this study are produced by cutting out from a c-oriented GaN bulk crystal grown by hydride vapor epitaxy. The LEDs have a dimension of 320 x 320 mu m(2) and are packed in an epoxide resin. The output power and external quantum efficiency (EQE) at a driving current of 20 mA are 1.76 mW and 3.0%, respectively, for the blue LED, 1.91 mW and 4.1% for the green LED, and 0.54 mW and 1.3% for the amber LED. The maximum output powers obtained with a maximum current of 200 mA are 19.0 mW (blue), 13.4 mW (green), and 1.9 mW (amber), while the Maximum EQEs are 4.0% at 140 mA (blue), 4.9% at 0.2 mA (green), and 1.6% at I mA (amber). It is confirmed that the emission light is polarized along the {11 (2) over bar2} direction, reflecting the low crystal symmetry of the {11 (2) over bar2} plane.