Aluminum Nitride Ceramic Substrates-Bonded Vertical Light-Emitting Diodes

We confirmed the potential of an aluminum nitride (AlN) substrate to be used as a bonding material for the high current operation of vertical light-emitting diodes (VLEDs). For the electrical connection to the top and bottom of the AlN substrate, via-holes were formed by laser drilling and then filled with Ag, which plays a role in improving the thermal dissipation from the VLEDs. The forward voltage of the fabricated AlN-bonded VLEDs was 3.54 V at 350 mA, which is similar to that of the Si-bonded VLEDs. It was also found that the light output power of the AlN-bonded VLEDs increased steadily with increasing injection current up to 1 A, while that of the Si-bonded VLEDs started to decrease at around 850 mA. In addition, the thermal resistance of the AlN-bonded VLEDs was significantly reduced, as compared with that of the Si-bonded VLEDs and conventional LEDs, under the same package conditions.