An Improved Ohmic Contact to n-Type N-Face GaN for Extremely Low Voltage-Operated Vertical Light Emitting Diodes

Low resistance and thermally stable n-type contact to N-polar GaN is essentially important for vertical light emitting diodes (VLEDs) . In this paper, the difference of the contacts deposited on wet-etching roughed and un-roughed surface was investigated. It was found that VLEDs with contacts deposited on roughed surface exhibits lower leakage currents yet higher operating voltage. Based on this, a new scheme for depositing metallization contacts has been developed. VLEDs fabricated based on this scheme shows extremely low operating voltage (2.75V@350mA), low reverse leakage current (0.015μA@-5V). There is no optical output compromise and aging test further confirmed its stability.