The interface formation between HfO2 and H-terminated Si(111) and Si(100) is studied by in situ infrared absorption spectroscopy during atomic layer deposition using alternating tetrakis-ethylmethylamino hafnium (TEMAH) and deuterium oxide (D2O) pulses. The HfO2 growth is initiated by the reaction of TEMAH with Si–H rather than D2O, and there is no evidence for SiO2 formation at moderate growth temperatures (∼100°C). Although Rutherford backscattering shows a linear increase of Hf coverage, direct observations of Si–H, Si–O–Hf, and HfO2 phonons indicate that five cycles are needed to reach the steady state interface composition of ∼50% reacted sites. The formation of interfacial SiO2 (∼0.7nm) is observed after postdeposition annealing at 700°C in ultrapure nitrogen.

Amorphous LaAlO3 thin films have been deposited by molecular beam deposition directly on silicon without detectable oxidation of the underlying substrate. We have studied these abrupt interfaces by Auger electron spectroscopy, high-resolution transmission electron microscopy, medium-energy ion scattering, transmission infrared absorption spectroscopy, and x-ray photoelectron spectroscopy. Together these techniques indicate that the films are fully oxidized and have less than 0.2 Å of SiO2 at the interface between the amorphous LaAlO3 and silicon. These heterostructures are being investigated for alternative gate dielectric applications and provide an opportunity to control the interface between the silicon and the gate dielectric.

Enhanced initial growth of atomic-layer-deposited metal oxides on hydrogen-terminated silicon Appl. Phys. Lett. 83, 740 (2003); 10.1063/1.1595719 Ultrathin nitrided-nanolaminate ( Al 2 O 3 / ZrO 2 / Al 2 O 3 ) for metal-oxide-semiconductor gate dielectric applications J.

We propose a mechanism for the nucleation of highly aligned biaxially textured MgO on amorphous Si 3 N 4 during ion beam-assisted deposition. Using transmission electron microscopy, reflection high-energy electron diffraction, energy dispersive x-ray analysis, and ellipsometery, we have observed that highly aligned biaxially textured grains emerge from a ''diffraction-amorphous'' film when the film thickens from 3.5 to 4.5 nm. Transmission electron microscopy dark-field images also show the onset of rapid grain growth during this same film thickness interval. These results suggest biaxial texturing through aligned solid phase crystallization. © 2002 American Institute of Physics. ͓DOI: 10.1063/1.1476385͔ Biaxially textured MgO is technologically interesting since it provides a suitable path for silicon integration of single-crystal-like films on amorphous substrates for many important perovskite oxide thin-film materials. Singlecrystalline MgO ͑001͒ has already been used as a substrate for BaTiO 3 and Pb͑Zr,Ti͒O 3 heteroepitaxy. 1,2 Ion beamassisted deposition ͑IBAD͒ creates biaxially textured films ͑polycrystalline films with a preferred in-plane and out-ofplane grain orientation͒ on amorphous substrates. 3 Incorporation of biaxially textured ferroelectric films with silicon integrated circuits would enable new types of actuators for microelectrical mechanical systems. Previous work has demonstrated high-quality heteroepitaxy of perovskites on Si, 4 but typical integrated circuit fabrication processes do not leave single-crystal Si available for oxide heteroepitaxy. By eliminating the requirement for a pre-existing heteroepitaxial template, IBAD MgO may provide an opportunity to incorporate ferroelectric materials on top of amorphous dielectric films in silicon integrated circuits following interconnect fabrication.In contrast to materials like yttria-stabilized zirconia ͑YSZ͒ where biaxial texture evolves slowly during one micron of IBAD growth, 5 the biaxial texture of IBAD MgO develops rapidly during the nucleation phase. Biaxial texturing mechanisms such as anisotropic sputtering, ion channeling, and anisotropic grain damage 6,7 have been proposed to explain biaxial texture evolution during growth of YSZ, but do not specifically address the nucleation-mediated biaxial texturing seen for MgO. It has been suggested that IBAD MgO grains nucleate with biaxial texture because surface energy is minimized with a ͑001͒ fiber texture, leaving inplane alignment to be achieved by ion channeling along the ͓011͔ zone axis. 3 High-temperature physical vapor deposition of MgO on amorphous SiO 2 favors nucleation with a ͑001͒ fiber texture, 8 but kinetic limitations result in nucleation with random orientation at room temperature. 9 We have used transmission electron microscopy ͑TEM͒, electron dispersive x-ray analysis ͑EDAX͒, ellipsometery, and in situ reflection high-energy electron diffraction ͑RHEED͒ to investigate IBAD MgO biaxial texture during the first few nanometers of film growth. Using electron-beam evaporation,...

Hydroxylation of chlorine-terminated silicon (111) and (100) by water vapor exposure has been studied as a function of substrate temperature using in situ infrared absorption spectroscopy. No hydroxyl is observed, as would have been expected from the surface reaction: Si–Cl(ads)+H2O(g)→Si–OH(ads)+HCl(g) (ads referring to adsorbed surface species). Instead, silicon oxide is formed upon removal of the Si–Cl bond at ∼325°C. This indicates that, while hydroxylation of the Cl-terminated silicon surface may occur, the hydroxylated surface formed by this reaction is not stable at the temperature necessary for the reaction.