Energy barriers at interfaces of (100)GaAs with atomic layer deposited Al2O3 and HfO2

Band alignment at the interfaces of (100)GaAs with Al2O3 and HfO2 grown using atomic layer deposition is determined using internal photoemission and photoconductivity measurements. Though the inferred conduction and valence band offsets for both insulators were found to be close to or larger than 2 eV, the interlayer grown by concomitant oxidation of GaAs reduces the barrier for electrons by approximately 1 eV. The latter may pose significant problems associated with electron injection from GaAs into the oxide. (C) 2008 American Institute of Physics. (DOI: 10.1063/1.3021374

Delayed crystallization of ultrathin Gd2O3 layers on Si(111) observed by in situ X-ray diffraction

We studied the early stages of Gd2O3 epitaxy on Si(111) in real time by synchrotron-based, high-resolution X-ray diffraction and by reflection high-energy electron diffraction. A comparison between model calculations and the measured X-ray scattering, and the change of reflection high-energy electron diffraction patterns both indicate that the growth begins without forming a three-dimensional crystalline film. The cubic bixbyite structure of Gd2O3 appears only after a few monolayers of deposition

Electronic structure of the interface of aluminum nitride with Si(100)

The band alignment at the interfaces of Si(100) with amorphous (a-) and crystallized (c-) AlN layers was analyzed using internal photoemission and photoconductivity spectroscopy. The bandgap of thin a-AlN layers grown using atomic layer deposition is found to be 5.8±0.1 eV, widening to 6.5±0.2 eV after annealing induced crystallization into the wurtzite phase. Internal photoemission of electrons from the Si valence band to the AlN conduction band was found to exhibit the same energy threshold of 3.2±0.1 eV in amorphous and crystallized AlN. The energy band diagrams of a-AlN/Si (100) and c-AlN/Si (100) interfaces are established. © 2008 American Institute of Physics

Impact of magnetite nanoparticle incorporation on optical and electrical properties of nanocomposite LbL assemblies.

Optical and electrical properties of polyelectrolyte/iron oxide nanocomposite planar films on silicon substrates were investigated for different amount of iron oxide nanoparticles incorporated in the films. The nanocomposite assemblies prepared by the layer-by-layer assembly technique were characterized by ellipsometry, atomic force microscopy, and secondary ion mass-spectrometry. Absorption spectra of the films reveal a shift of the optical absorption edge to higher energy when the number of deposited layers decreases. Capacitance-voltage and current-voltage measurements were applied to study the electrical properties of metal-oxide-semiconductor structures prepared by thermal evaporation of gold electrodes on nanocomposite films. The capacitance-voltage measurements show that the dielectric constant of the film increases with the number of deposited layers and the fixed charge and the trapped charge densities have a negative sign

Impact of magnetite nanoparticle incorporation on optical and electrical properties of nanocomposite LbL assemblies.

Optical and electrical properties of polyelectrolyte/iron oxide nanocomposite planar films on silicon substrates were investigated for different amount of iron oxide nanoparticles incorporated in the films. The nanocomposite assemblies prepared by the layer-by-layer assembly technique were characterized by ellipsometry, atomic force microscopy, and secondary ion mass-spectrometry. Absorption spectra of the films reveal a shift of the optical absorption edge to higher energy when the number of deposited layers decreases. Capacitance-voltage and current-voltage measurements were applied to study the electrical properties of metal-oxide-semiconductor structures prepared by thermal evaporation of gold electrodes on nanocomposite films. The capacitance-voltage measurements show that the dielectric constant of the film increases with the number of deposited layers and the fixed charge and the trapped charge densities have a negative sign

Electronic structure of silicon interfaces with amorphous and epitaxial insulating oxides: Sc2O3, Lu2O3, LaLuO3

Spectroscopy of internal photoemission, photoconductivity, and optical absorption is used to characterize the differences in the electronic structure of interfaces of silicon with several oxides (Sc2O3, Lu2O3, LaLuO3) grown as epitaxial layers or as amorphous films. As compared to their crystalline counterparts, the amorphous oxides exhibit significant band-tail states predominantly associated with the smearing-out of the conduction band edge. In SC203 a difference in bandgap width between the crystalline and amorphous phases, caused by variation of the energy of the oxide valence band top, is also observed. No structure-sensitive interface dipoles are found to affect the band alignment at the Si/oxide interfaces