Mg-doped p-GaN epitaxial layers prepared 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 degreesC. In0.23Ga0.77N/GaN multiquantum well (MQW) light emitting diodes (LEDs) with such a low 800 degreesC-grown p-GaN cap layer were also fabricated. It was found that we could enhance the LED output intensity by more than 90% with the low 800 degreesC-grown p-GaN cap layer, as compared to the conventional high 1000 degreesC-grown p-GaN cap layer. (C) 2003 Elsevier Ltd. All rights reserved.