RED LIGHT EMITTING SCHOTTKY DIODES ON p-TYPE GaN/AlN/Si(111) SUBSTRATE

Abstract

High quality GaN layers doped with Mg were grown on Si (111) substrates using high temperature AlN as buffer layer by radio-frequency molecular beam epitaxy. From the Hall measurements, fairly uniform high hole concentration as high as (4–5) × 1020 cm -3 throughout the GaN was achieved. The fabrication of the device is very simple. Nickel ohmic contacts and Schottky contacts using indium were fabricated on Mg -doped p-GaN films. The light emission has been obtained from these thin film electroluminescent devices. Thin film electroluminescent devices were operated under direct current 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. Thin film electroluminescent devices were able to emit light. However, electrical and optical differences could be observed from the two different probing methods. The red light color could be observed when the potential between the electrodes was increased gradually under forward bias of 8 V at room temperature. Electrical properties of these thin film electroluminescent devices were characterized by current–voltage (I–V) system, the heights of barriers determined from the I–V measurements were found to be related to the electroluminescence.