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The interfacial electronic structure of Ga2O3(Gd2O3) (GGO) on n-Ge(001) is determined using high-resolution synchrotron radiation photoemission. The excitation photon energy was specifically chosen to observe the interaction at the GGO/Ge interface (hv = 463 eV) as well as the possible diffusion of Ge up to the GGO surface (hν = 120 eV). The Ge 3d core-level spectra were fit to extract the contributing components. Photoemission measurements were done for four samples, as deposited, N2 annealed, CF4 plasma treated, and the combined CF4 plasma treated and N2 annealed. No surface passivation was employed prior to the dielectric deposition. SRPES data clearly showed that the elemental Ge in the as-deposited sample was effectively kept in the wafer. Prevention of Ge diffusion was attributed to formation of a thin germanatelike oxide layer. Other than contributions from bulk Ge, an analytical fit to the Ge 3d cores gives two components that are associated with bonding to Gd2O3 (GdGe*) and to Ga2O3 (GaGe*), which had chemical shifts of 3.46 and 1.80 eV, respectively. We hereby label them as MGe*, where M stands for either Gd2O3 or Ga2O3. Area occupations of the GdGe* and GaGe* oxides are ∼87% and ∼10%, respectively. A CF4 plasma treatment disturbs the film itself as well as the interfacial oxide so that the GGO surface begins to show both elemental Ge and Ga. Nevertheless, the follow-up N2 annealing produces the GdGe*+GaGe* layer with characteristics similar to those at the GGO/Ge interface. Both GdGe* and GaGe* states in the CN-treated sample show simultaneously a smaller chemical shift by 0.31 ± 0.02 eV than those in the as-deposited sample. The treatments also induce upward band bending on both the high κ and the Ge sides, which causes the valence band offset at the GGO/Ge interface to be 2.95 eV. [ABSTRACT FROM AUTHOR]

High-resolution core-level photoemission analysis using synchrotron radiation was used to investigate the superior electrical performance of aGa2O3(Gd2O3) gate dielectric on Ge(001) after CF4 treatment. Prior to the treatment, a thin germanate-like oxide layer that formed at the interface prevented Ge from diffusing to the surface. The Ge surface retained a small amount of buckled dimers from the as-grown sample. The buckled dimers were quickly removed by CF4 plasma treatment followed by an annealing process, resulting in a more uniform interface than that of the as-grown sample. The detailed interfacial electronic structure for the untreated and treated samples are presented. [ABSTRACT FROM AUTHOR]

Atomic-layer-deposited high κ dielectric HfO2 films on air-exposed In0.53Ga0.47As/InP (100), using Hf(NCH3C2H5)4 and H2O as the precursors, were found to have an atomically sharp interface free of arsenic oxides, an important aspect for Fermi level unpinning. A careful and thorough probing, using high-resolution angular-resolved x-ray photoelectron spectroscopy (XPS) with synchrotron radiation, however, observed the existence of Ga2O3, In2O3, and In(OH)3 at the interface. The current transport of the metal-oxide-semiconductor capacitor for an oxide 7.8 nm thick follows the Fowler–Nordheim tunneling mechanism and shows a low leakage current density of ∼10-8 A/cm2 at VFB+1 V. Well behaved frequency-varying capacitance-voltage curves were measured and an interfacial density of states of 2×1012 cm-2 eV-1 was derived. A conduction-band offset of 1.8±0.1 eV and a valence-band offset of 2.9±0.1 eV have been determined using the current transport data and XPS, respectively. [ABSTRACT FROM AUTHOR]

A microscopic view of in situ atomic layer deposition Al2O3 on clean n-GaAs (001)-4 × 6 surfaces probed by high-resolution synchrotron radiation photoemission is presented. The precursors of trimethylaluminum (TMA) and water partially and selectively bond with the surface atoms without disturbing the atoms in the subsurface layer. The first-cycle TMA acts differently on the surface As atoms; namely, TMA is dissociative on As in the As-Ga dimer but is physisorbed on As that is 3-fold Ga coordinated. Water drastically alters the TMA-covered surface to etch off the dissociated TMA with As, giving Ga-O bonding for the later deposition of Al2O3 and at the same time to transform the configuration of the physisorbed TMA to bond strongly with As. Approximately six cycles of purges (TMA + water) are required before the interaction at the interface is complete. In comparison, the e-beam deposition of Al2O3 on GaAs greatly disturbs the III-V surface so that a high As 4+ charge state appears and the surface Ga atoms become clustered. [ABSTRACT FROM AUTHOR]