A systematic study of the interface engineering and dielectric properties of nanolaminated hafnium aluminate on GaAs is presented. The dielectrics were deposited using atomic layer deposition of alternating cycles of HfO2 and Al2O3 on GaAs substrates. High resolution x-ray photoelectron spectroscopy (XPS) showed differences in space charge amounts at the interface for the two surface treatments [NH4OH or (NH4)2S]. In-situ XPS analysis shows that chemical bonding to oxygen across the nanolaminate film is independent of the interface formation conditions. In addition, the GaAs surface treated with (NH4)2S shows a decreased band bending and slightly thinner films with respect to NH4OH.

The effect of water and ozone as the oxidant in the atomic layer deposition ͑ALD͒ of aluminum oxide on the ammonium-sulfidepassivated In 0.53 Ga 0.47 As surface is compared using X-ray photoelectron spectroscopy ͑XPS͒ after each "half-cycle" of the ALD process. While the first half-cycle of the aluminum precursor tri-methyl aluminum ͑TMA͒ reduces the residual native oxides to within detection limits of XPS, the ozone oxidation process causes significant reoxidation of the substrate in comparison to the water-based process. Subsequent TMA pulses fail to remove the excess interfacial oxides caused by ozone oxidation, resulting in the formation of an oxide interlayer.As scaling continues to reduce the thickness of the SiO 2 dielectric toward its physical limit, 1 the introduction of new dielectrics coupled with the integration of high-mobility III-V materials is becoming important for future complementary metal oxide semiconductor technology. 2 In order to engineer a useful interface between the high-dielectric and the high-mobility substrate, deposition techniques with the potential to grow layers with minimal interface states and high surface conformality are needed to reduce frequency dispersion and charge trapping at the interface. 3 This requirement makes atomic layer deposition ͑ALD͒ a promising technique for this process. 4,5 While having a dielectric constant lower than other high-k dielectric materials, Al 2 O 3 ͑ Ϸ 10͒ is currently being investigated for ALD deposition due to the availability of high-quality metal precursors. 6 Typically, a gas-phase metal alkyl compound is used as the metal carrier while water is used for the sequential oxidation process. However, due to the wetting nature of H 2 O, there is the potential that residual water left behind from the oxidation cycles can remain in the ALD reactor precursor delivery system and potentially degrade the metal precursor before it reaches the surface of the material, increasing the chance of contamination in the dielectric layer ͑e.g., by particulate formation͒. 7,8 This study compares the effect of water oxidation on the deposition process to that of oxidation using ozone ͑O 3 ͒ 9 to determine if there are any significant differences in the interface between the dielectric and the ammonium-sulfide-treated In 0.53 Ga 0.47 As surface characterized using in situ X-ray photoelectron spectroscopy ͑XPS͒. Due to the associated sticking coefficients of O 3 and H 2 O, it is more facile to evacuate O 3 from the reactor during the purge relative to H 2 O, thus leaving no residual oxygen to decompose the tri-methyl aluminum ͑TMA͒ into Al 2 O 3 before it reaches the surface, reducing the possibility of forming O-H bonds in the film. 10 Sulfur-doped ͑4 ϫ 10 17 cm −3 ͒ In 0.53 Ga 0.47 As ͑ϳ7.6 cm diameter͒ grown by metallorganic vapor phase epitaxy on heavily doped ͑S ϳ 4 ϫ 10 18 cm −3 ͒ InP͑100͒ wafers were used in this study. The Al 2 O 3 thin films were deposited by ALD on ammonium-sulfidepassivated ͓10% ͑NH 4 ͒ 2 S for 20 min at ϳ20°C͔ surfaces ͑ϳ1 ϫ 1 cm 2 ͒...