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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.

Display Omitted The negative VFB shift and thinner EOT with ALD La2O3 capping.The more negative VFB with ALD La2O3 using La(fAMD)3 precursor.Further EOT scaling with ALD La2O3 using La(fAMD)3 precursor.Compared to ALD La2O3, more VFB shift and thinner EOT with PVD La2O3. We have investigated the electrical characteristics - flat band voltage (VFB) shift, equivalent oxide thickness (EOT) scaling and charge trapping - of atomic layer deposition (ALD) La2O3 capped high-k gate dielectrics (HfO2, HfSiOx, and HfSiON) in the metal-oxide-semiconductor (MOS) device structure, where two different lanthanum precursors - ? lanthanum formamidinate, La(fAMD)3, and ? lanthanum betadiketonate, La(thd)3, - were used for ALD capping layer. Regardless of precursors, La2O3 capping layer on the ALD high-k films leads to negative VFB shift and thinner EOT as increasing capping thickness. However, more shift and further EOT scaling are observed with La2O3 thin film using La(fAMD)3. In addition, La2O3 capping layer using La(fAMD)3 precursor shows lower interface state density (Dit) and stronger immunity against charge trapping than La2O3 capping layer with La(thd)3 precursor. Similar trends are attained with Si containing HfO2 - HfSiOx and HfSiON, but amount of VFB shift and EOT reduction is smaller than that of HfO2-based device, resulting from suppressed La-diffusion due to stronger Si-O bonds as well as nitrogen blocking in the dielectrics.

Hydrogen (H 2 ) plasma treatment at the interface between 4H-SiC substrate and Al 2 O 3 dielectric prepared by the atomic layer deposition (ALD) was performed and its effects on capacitance–voltage characteristics as well as the interface state density ( D it ) was evaluated with metal oxide semiconductor devices. The atomic force microscopy result indicates that the remote H 2 plasma treatment reduces surface roughness. Compared with the non-passivated devices, lower leakage current, lower hysteresis and higher breakdown voltage are attained with remotely hydrogen plasma-treated devices. Without post metallization annealing (PMA), D it value more than 10 14 eV −1 cm −2 is attained with hydrogen plasma passivated devices, indicating plasma-induced damage on the surface. However, using PMA, D it of the H 2 plasma treated device is significantly reduced to as low as 1.00 × 10 12 eV −1 cm −2 at E c − E t = 0.4 eV and is about five times lower than that of sample without H 2 plasma passivation ( D it = 4.84 × 10 12 eV −1 cm −2 ).