Assessment of GaN Surface Pretreatment for Atomic Layer Deposited High-kDielectrics

We report the effects of GaN surface pretreatments on the material and electrical properties of Al 2 O 3 dielectric deposited by atomic layer deposition (ALD). A layer of Al 2 O 3 was deposited at different temperatures on metal organic chemical vapor deposition grown n-GaN that was treated with either H 2 O 2 :H 2 SO 4 (1:5, piranha), HCl:H 2 O (1:1, HCl), or HF:H 2 O (1:1, HF) prior to Al 2 O 3 deposition. The Al 2 O 3 layers on piranha- and HF-treated GaN were observed to be uniformly smooth. The piranha pretreatment resulted in the lowest hysteresis. Pretreatment of the GaN surface with piranha removes carbon and hydroxylates the surface, resulting in better quality ALD Al 2 O 3 .