The effects of (NH4)2Sx treatment on n-GaN MOS device with nano-laminated ALD HfAlOx and Ru gate stack

Display Omitted GaN MOS with ALD HfAlOx/Ru with (NH4)2Sx pre-treatment.Better roughness, higher VBD, and smaller frequency dependence using (NH4)2Sx.(NH4)2Sx suppresses interfacial oxide regrowth on the GaN substrate.The Dit can be reduced further with longer treatment time. The effects of ammonium poly-sulfide, (NH4)2Sx, treatment on the surface of GaN metal oxide semiconductor (MOS) device with nano-laminated atomic layer deposition (ALD) HfAlOx gate dielectric and Ru gate electrode were investigated and compared with HCl pre-treatment. Compared with sample without sulfur (S) passivation, S-passivated sample shows improved surface roughness, increased capacitance, higher breakdown voltage, smaller frequency dependence, lower interface state density (Dit). It is found that (NH4)2Sx can remove native oxide and passivate the surface and interface states. Surface oxidation is suppressed due to higher strength in the NS bonds than that of the NO bonds. Further improvement is observed with increasing (NH4)2Sx treatment time.