p-n ZnO Light-emitting Diode Fabricated on a-sapphire Substrate

A ZnO homo-junction light-emitting diode (LED) was fabricated on a-Al_2O_3 substrate by plasma-assistant molecular beam epitaxy. NO plasma activated by a radio frequency atomic source was used to grow the p-type ZnO layer of the LED. The current-voltage measurements at low temperatures showed a typical (diode) characteristic with a threshold voltage about 4.0 V at forward bias. Electroluminescence band of the ZnO LED is located at the blue-violet region at 80 K, and the electroluminescence still can be observed up to 200 K.