Atomic-layer deposition for improved performance of III-N avalanche photodiodes

We have investigated surface modification methods for avalanche photodiodes using dielectrics deposited by atomic layer deposition (ALD). Arrays of mesa GaN APDs were fabricated, and ALD Al₂O₃ was used for sidewall passivation prior to completing the APD array. The use of ALD Al ₂O₃ in this manner was observed to result in a large average improvement in APD dark current when compared with devices using more conventional SiO₂ passivation layers produced by chemical vapor deposition. Co-processed metal-oxide-semiconductor (MOS) capacitors fabricated with the same passivation layers show significant improvement in electrical interface quality for devices with ALD Al₂O₃.