Kazuyuki Hirose

Accurate determination of SiO2 film thickness by x-ray photoelectron spectroscopy

We established the number of Siu200a2p photoelectrons emanating from a Si(100) substrate covered with a silicon–oxide film as a function of azimuthal and polar angles using the oxide film thickness as a parameter. The elastic and inelastic scattering cross sections of Siu200a2p photoelectrons in silicon oxide were deduced by reproducing the experimental results with Monte Carlo simulation for the path of Siu200a2p photoelectrons in silicon oxide. Based on the simulation, we found that the elastic scattering of Siu200a2p photoelectrons in silicon oxide could effectively be neglected in several specific directions. We also found that an emitting direction different to these specific directions is indispensable when precisely determining the thickness using XPS with a large receiving angle.

Correlation between the dipole moment induced at the Slater transition state and the optical dielectric constant of Si and Al compounds

We calculate the difference between the valence charges of the ground state and the Slater transition state for several types of Si compounds and Al compounds. We assume the dipole moment induced by core-hole generation at the Slater transition state to be the product of the valence charge difference and the bond length of the compounds. We find that the calculated dipole moment has a strong linear correlation well with (e−1)/(e+2), which is deduced from experimental values of the optical dielectric constant e.

X-ray photoelectron spectroscopy study of dielectric constant for Si compounds

The authors measure the difference of core-level binding energy shifts for Si 1s and Si 2p, ΔE1s-ΔE2p, for various Si compounds using high-resolution high-energy synchrotron radiation. They find that the ΔE1s-ΔE2p values are in very good correlation with the dielectric constant values of the Si compounds. Using this relation, they deduce the local dielectric constant for each of the Si intermediate oxidation states formed at the SiO2∕Si interface. The results are in good agreement with values predicted by a first-principles calculation.

Relationship between optical dielectric constant and XPS relative chemical shift of 1s and 2p levels for dielectric compounds

We find a new relationship between the optical dielectric constant of Al dielectric films and their chemical shifts measured by X-ray photoelectron spectroscopy (XPS). We measure the difference between core-level binding energy shift for Al 1s and core-level binding energy shift for Al 2p, ΔE1s - ΔE2p, for AlN using high-resolution high-energy synchrotron radiation. We find that ΔE1s - ΔE2p correlates well with the optical dielectric constants of Al, AlN, and Al2O3. This is consistent with the case of our previously reported Si compounds. First-principles calculations are performed to determine the mechanism behind the observed correlation.

Physical origin of stress-induced leakage currents in ultra-thin silicon dioxide films

The physical origin of stress-induced leakage currents (SILC) in ultra-thin SiO 2 films is described. Assuming a two-step trapassisted tunneling process accompanied with an energy relaxation process of trapped electrons, conditions of trap sites which are origin of SICL are quantitatively found. It is proposed that the trap site location and the trap state energy can be explained by a mean-free-path of hole in SiO 2 films and an atomic structure of the trap site by the O vacancy model.

Soft X-ray irradiation effect on surface structure of CH 3 NH 3 PbI 3 perovskite in multi-film stack device

Soft X-ray exposure effects on CH3NH3PM3 perovskite in a patterned device sample with a similar structure to solar cells, a promising candidate for X-ray detectors, have been investigated with an X-ray Photoelectron Spectroscopy (XPS) time-dependent measurement method. Our experimental analyses demonstrate compositional change from CH3NH3PM3 to PbI2 due to evaporation of methylammonium iodide.

High-k Gate Dielectric Films Studied by Extremely Asymmetric X-ray Diffraction and X-ray Photoelectron Spectroscopy

We studied HfAlOx(N)/SiO2/Si films which were fabricated by the layer-by-layer deposition and annealing (LL-D&A) method with different annealing conditions. In this time, in-situ annealing was performed at various temperatures in an NH3 ambient. In addition, post-deposition annealing (PDA) was performed for some samples. For each sample, the interfacial lattice strain was evaluated using extremely asymmetric X-ray diffraction and the local dielectric constant near the Al atoms was measured by X-ray photoelectron spectroscopy (XPS). Observation of the strain field was done by measuring the X-ray rocking curve of the Si 113 reflection of the Si (001) substrate under grazing incidence conditions. It was found that in the case of the samples without PDA, for higher in-situ annealing temperatures compressive strain is introduced and the local dielectric constant becomes lower. For the samples with PDA, the differences of the lattice strain and the local dielectric constant are small for different in-situ annealing temperatures.

X-ray photoelectron spectroscopy study on dielectric properties at gate insulator film/Si interfaces

The authors propose a new method to estimate the local dielectric constant of an ultrathin gate insulator film formed on Si substrates by using X-ray photoelectron spectroscopy (XPS). First the authors measure the difference of core-level binding energy shifts for Si 1s and Si 2p, DeltaE1s DeltaE2p, for various Si compounds using high-resolution high-energy synchrotron radiation. the authors find that the DeltaE1s - DeltaE2p values are in very good correlation with the dielectric constant values of the Si compounds. Then, using this relation, the authors deduce the local dielectric constant for ultrathin SiO2 film formed on Si substrates. The results are in good agreement with values predicted by a first-principles calculation