Electrical resistivity and magnetotransport are explored for thin (3 – 30 nm), epitaxial LaNiO3 films. Films were grown on three different substrates to obtain LaNiO3 films that are coherently strained, with different signs and magnitude of film strain. It is shown that d-band transport is inhibited as the layers progress from compression to tension. The Hall coefficient is “hole like”. Increasing tensile strain causes the film resistivity to increase, causing strong localization to appear below a critical thickness.

Hafnium oxide gate dielectrics doped with a one to two percent of aluminum are grown on In0.53Ga0.47As channels by codeposition of trimethylaluminum TMA and hafnium tertbutoxide HTB. It is shown that the addition of TMA during growth allows for smooth, amorphous films that can be scaled to 5 nm physical thickness. Metal-oxide-semiconductor capacitors MOSCAPs with this dielectric have an equivalent oxide thickness of 1 nm, show an unpinned, efficient Fermi level movement and lower interface trap densities than MOSCAPs with HfO2 dielectrics grown by sequential TMA/HTB deposition.

A heterojunction Mott field effect transistor (FET) is proposed that consists of an epitaxial channel material that exhibits an electron correlation induced Mott metal-to-insulator transition. The Mott material is remotely (modulation) doped with a degenerately doped conventional band insulator. An applied voltage modulates the electron transfer from the doped band insulator to the Mott material and produces transistor action by inducing an insulator-to-metal transition. Materials parameters from rare-earth nickelates and SrTiO3 are used to assess the potential of the “modulation-doped Mott FET” (ModMottFET or MMFET) as a next-generation switch. It is shown that the MMFET is characterized by unique “charge gain” characteristics as well as competitive transconductance, small signal gain, and current drive.

Epitaxial GdTiO3 /SrTiO3 structures with different SrTiO3 layer thicknesses are grown on 001 LaAlO30.3Sr2AlTaO60.7 substrate surfaces by hybrid molecular beam epitaxy. It is shown that the formation of the pyrochlore Gd2Ti2O7 phase can be avoided if GdTiO3 is grown by shuttered growth, supplying alternating monolayer doses of Gd and of the metalorganic precursor that supplies both Ti and O. Phase-pure GdTiO3 films grown by this approach exhibit magnetic ordering with a Curie temperature of 30 K. The electrical transport characteristics can be understood as being dominated by a conductive interface layer within the SrTiO3.

We demonstrate, using high-mobility SrTiO3 thin films grown by molecular beam epitaxy, that stress has a pronounced influence on the electron mobility in this prototype complex oxide. Moderate strains result in more than 300% increases in the electron mobilities with values exceeding 120 000 cm2/V s and no apparent saturation in the mobility gains. The results point to a range of opportunities to tailor high-mobility oxide heterostructure properties and open up ways to explore oxide physics.

Methods to extract trap densities at high-permittivity k dielectric/III-V semiconductor interfaces and their distribution in the semiconductor band gap are compared. The conductance method, the Berglund intergral, the Castagné–Vapaille high-low frequency, and Terman methods are applied to admittance measurements from metal oxide semiconductor capacitors MOSCAPs with high-k/ In0.53Ga0.47As interfaces with different interface trap densities. The results are discussed in the context of the specifics of the In0.53Ga0.47As band structure. The influence of different conduction band approximations for determining the ideal capacitance-voltage CV characteristics and those of the MOSCAP parameters on the extracted interface trap density are investigated. The origins of discrepancies in the interface trap densities determined from the different methods are discussed. Commonly observed features in the CV characteristics of high-k/ In0.53Ga0.47As interfaces are interpreted and guidelines are developed to obtain reliable estimates for interface trap densities and the degree of Fermi level unpinning for high-k/ In0.53Ga0.47As interfaces.

A number of binary oxides have been predicted to be thermodynamically stable in contact with Si and are candidates to replace SiO2 in complementary metal-oxide-semiconductors. However, reactions leading to the formation of interfacial silicide, silicate, or SiO2 layers have been reported when these oxides are exposed to high temperatures during device processing. Different pathways have been proposed in the literature to explain these reactions. In this article, a thermodynamic analysis of the proposed reactions is performed. The analysis includes gaseous species, because typical gate dielectrics are ultrathin layers and diffusivities for species from the surrounding atmosphere, such as oxygen, may be high. Furthermore, nonstoichiometry of the high-k oxide, as may be resulting from nonequilibrium deposition processes or reducing atmospheres during processing is also considered. Studies are proposed to distinguish between possible reaction mechanisms. Finally guidelines for stable interfaces are presented. (C) 2004 American Vacuum Society.

Seebeck coefficients and conductivity of La-doped SrTiO3 thin films grown by molecular beam epitaxy were measured as a function of carrier concentration. At low carrier concentrations, thin films show very high Seebeck coefficients (up to 980 μV K−1). The maximum thermoelectric power factor was 39 μWcm−1 K−2 at a carrier concentration of 7×1020 cm−3. La-delta-doped superlattices were also characterized and exhibited Seebeck coefficients of ∼ 500 μV K−1. The results are discussed in the context of reports of enhanced Seebeck coefficients in delta-doped SrTiO3 superlattices.

The electrical characteristics, in particular interface trap densities, oxide capacitance, and Fermi level movement, of metal oxide semiconductor capacitors with HfO2 gate dielectrics and In0.53Ga0.47As channels are investigated as a function of postdeposition annealing atmosphere. It is shown, using both conductance and Terman methods, that the Fermi level of nitrogen annealed stacks is effectively pinned at midgap. In contrast, samples annealed in forming gas show a large band bending in response to an applied gate voltage and a reduced midgap interface trap density compared to those annealed in nitrogen.