Improved light output power of InGaN/GaN MQW LEDs by lower temperature p-GaN rough surface

Mg-doped p-GaN epitaxial layers grown at different temperatures were prepared and characterized. It was found that we could achieve a higher hole concentration and a rough surface by reducing the growth temperature down to 800 C. In0.23Ga0.77N/GaN multiquantum well (MQW) light-emitting diodes (LEDs) with such a low 800 C-grown p-GaN cap layer were also fabricated. It was also found that one could lower the LED operation voltage from 3.68 to 3.36 V and enhance the 20 mA LED output power by the 800 C-grown p-GaN cap layer. However, it was also found the leakage current was larger and the lifetime was shorter for the LEDs with the 800 C-grown p-GaN cap layer. (C) 2004 Elsevier B.V. All rights reserved.