Low applied bias for p-GaN electroluminescent devices

Nickel ohmic contacts and Schottky contacts using silver or titanium were fabricated on Mg-doped p-GaN films. The light emission has been obtained from these thin film electroluminescent devices (ELDs). These ELDs were operated under direct current (DC) bias. Schottky and ohmic contacts used as cathode and anode were employed in these investigations. Alternatively, two Schottky contacts could be probed as cathode and anode. Both ELDs were able to emit light. However, electrical and optical differences could be observed from the two different probing methods. ELDs started to emit light under forward bias of 3 V at room temperature in a dark environment. The change of light colour from yellowish white, green, blue to violet could be observed when the potential between the electrodes was increased gradually. The light intensity emitted increased with the applied bias. Electrical properties of these ELDs were characterized by current-voltage (I-V) system, the barriers heights determined from the I-V measurements were found to be related to the electroluminescence.