Effects of Al thickness in Ti/Al/Ti/Au ohmic contact on AlGaN/GaN heterostructures are studied. Samples having Al thickness of 30, 90 and 120 nm in Ti/Al/Ti/Au have been investigated by electrical and X-ray photoelectron spectroscopy (XPS) depth profile analysis. It is found that thick Al samples show lower resistance and formation of Al-based alloy under the oxidized Al layer.

Nitrogen adsorption on thermally cleaned Si(100) surfaces by pure and plasma excited NH$_{3}$ is investigated by extit{in situ} IR absorption spectroscopy and ex-situ X-ray photoelectron spectroscopy with various temperatures from RT (25$^{circ}$C) to 800$^{circ}$C and with a treatment time of 5,min. The nitrogen coverage after the treatment varies according to the treatment temperature for both pure and plasma excited NH$_{3}$. In case of the pure NH$_{3}$, the nitrogen coverage is saturated as low as 0.13--0.25 mono layer (ML) while the growth of the nitride film commenced at 550$^{circ}$C. For the plasma excited NH$_{3}$, the saturation coverage was measured at 0.54,ML at RT and it remained unincreased from RT to 550$^{circ}$C. This indicates that the plasma excited NH$_{3}$ enhances the nitrogen adsorption near at RT. It is found that main species of N is Si$_{2}=$ NH in case of the plasma excited NH$_{3}$ at RT while the pure NH$_{3}$ treatment gives rise to the Si--NH$_{2}$ passivation with Si--H at RT. We discuss the mechanism of the nitrogen adsorption on Si(100) surfaces with the plasma excited NH$_{3}$ in comparison with the study on the pure NH$_{3}$ treatment.

We investigated the effects of chemical treatments for removing native oxide layers on InAlN surfaces by X-ray photoelectron spectroscopy (XPS). The untreated surface of the air exposed InAlN layer was covered with the native oxide layer mainly composed of hydroxides. Hydrochloric acid treatment and ammonium hydroxide treatment were not efficient for removing the native oxide layer even after immersion for 15 min, while hydrofluoric acid (HF) treatment led to a removal in a short treatment time of 1 min. After the HF treatment, the surface was prevented from reoxidation in air for 1 h. We also found that the 5-min buffered HF treatment had almost the same effect as the 1-min HF treatment. Finally, an attempt was made to apply the HF-based treatment to the metal-InAlN contact to confirm the XPS results.

The copper nitride surface characteristics according to atmospheric pressure plasma (APP) and excimer ultraviolet (EUV) treatment were compared using XPS and AFM. As the result of XPS analysis result, in C1s, the organic material removal effect was greater for EUV treatment than for APP, and the oxygen content was found to be low. In Cu (933 eV) area, the shoulder peak of Cu compound was detected, and the reduction was greater for EUV processing than for APP. In the AFM phase image which could be analyzed using the superficial viscoelasticity, the same trend was observed. On the copper nitride surface, the weak boundary O layer is formed according to the clean processing, and such phenomenon was interpreted as a factor for lowering the affinity with polymer.

A disentanglement puzzle consists of mechanically interlinked pieces, and the puzzle is solved by disentangling one piece from another set of pieces. A cast puzzle is a type of disentanglement puzzle, where each piece is a zinc die-casting alloy. In this paper, we consider the generalized cast puzzle problem whose input is the layout of a finite number of pieces (polyhedrons) in the 3-dimensional Euclidean space. For every integer k ≥ 0, we present a polynomial-time transformation from an arbitrary k-exponential-space Turing machine M and its input x to a cast puzzle c1 of size k-exponential in |x| such that M accepts x if and only if c1 is solvable. Here, the layout of c1 is encoded as a string of length polynomial (even if c1 has size k-exponential). Therefore, the cast puzzle problem of size k-exponential is k-EXPSPACE-hard for every integer k ≥ 0. We also present a polynomial-time transformation from an arbitrary instance f of the SAT problem to a cast puzzle c2 such that f is satisfiable if and only if c2 is solvable.

We prepared HfO2 films by atomic layer deposition (ALD) on three kinds of silicon substrate surfaces (chemical oxide, HF-last surface and thermal oxide), and characterized their morphologies, structures, compositions, and crystallinities by physical analysis. The results revealed that the as-deposited HfO2 films consisted of nano-crystalline particles with a different crystalline system from that of the annealed films. The size of the nano-crystalline particles on the film on the chemical oxide was smaller than those on the other surfaces. The reason is thought to be the difference in OH concentration on the substrate surface. The predominant crystalline phases of all HfO2 films were monoclinic after annealing. Moreover, the film prepared on the chemical oxide had the smoothest surface after annealing. However, island structures with grain boundaries developed in the films on the other surfaces.

The prospects of electron spectroscopy of working organic electronic device structures are discussed. The experimental consideration and the result of actual measurement are presented.

The fabrication process of a novel Si interface control layer (Si ICL)-based oxide-free insulated gate structure for InP metal-insulator-semiconductor field effect transistors (MISFETs) was successfully characterized and optimized using in-situ reflection of high-energy electron diffraction (RHEED), Raman scattering spectroscopy, X-ray photoelectron spectroscopy (XPS) and capacitance-voltage (C-V) techniques, and applied for fabrication of MISFETs. RHEED observation indicated that the optimum initial thickness of the Si ICL with single crystal pseudomorphic growth of Si on InP is 10 . Raman scattering spectroscopy showed existence of surface strain on InP covered with the Si ICL without changing LO-phonon peak width, indicating that the Si ICL is grown in a pseudomorphic fashion. A detailed XPS analysis showed that Fermi level pinning was largely reduced by the growth of the Si ICL and its partial electron cyclotron resonance (ECR) plasma nitridation realizing an optimum Si ICL thickness of 5 with a good interface to SiNx. C-V measurement confirmed that the optimum Si ICL-based gate formation process realized a full swing of Fermi level almost over the entire bandgap. The fabricated MISFET using the optimum gate structure exhibited excellent gate controllability and stable operation with a low gate leakage currents.

Surface damage to n-type silicon wafers induced by Reactive Ion Etching (RIE) with CF4 gas was evaluated using X-ray photoelectron spectroscopy (XPS) and the current-voltage (I-V) characteristics of Au/n-Si Schottky diodes fabricated on the damaged surface. The reaction products (SiF, SiF2, and SiF3) in the damaged layer were detected by XPS. Assuming the surface damage on a silicon wafer induced by RIE acts as a donor, the donor density was found to be about 21019 cm-3. The distribution of SiF3 and the donor density in the depth direction were almost equal. The thickness of the damaged layer was about 15 nm. These findings suggest that the donor in the damaged layer on a silicon surface induced by RIE may be SiF3.

Hydrogen termination of HF-treated Si surfaces and the oxidation kinetics have been studied by x-ray photoelectron spectroscopy (XPS) and Fourier Transform Infrared Spectroscopy (FT-IR) Attenuated Total Reflection (ATR). The oxidation of hydrogen-terminated Si in air or in pure water proceeds parallel to the surface presumably from step edges, resulting in the layer-by-layer oxidation. The oxide gryowth rate on an Si(100) surface is faster than (110) and (111) when the wafer is stored in pure water. This is interpreted in terms of the steric hindrance against molecular oxygen penetration throughth the (110) and (111) surfaces where the atom void size is equal to or smaller than O2 molecule. The oxide growth rate in pure water for heavily doped n-type Si is significantly high compared to that of heavily doped p-type Si. This is explained by the conduction electron tunneling from Si to absorbed O2 molecule to form the O2- state. O2- ions easily decompose and induce the surface electric field, enhancing the oxidation rate. It is found that the oxidation of heavily doped n-type Si in pure water is effectively suppressed by adding a small amount (1003600 ppm) of HCl.

Chemical structures of native oxides formed during wet chemical treatments of silicon surfaces were investigated using X-ray Photoelectron Spectroscopy (XPS) and Fourier Transformed Infrared. Attenuated Total Reflection (FT-IR-ATR). It was found that the amounts of Si-H bonds in native oxide and at native oxide/ silicon interface are negligibly small in the case of native oxides formed in H2SO4-H2O2 solution. Based on this discovery, it was found that native oxides can be characterized by the amount of Si-H bonds in the native oxide and the combination of various wet chemical treatments with the treatment in NH4OH-H2O2-H2O solution results in the drastic decrease in the amount of Si-H bonds in the native oxides.

The initial stages of SiO2/Si interface formation on a Si(111) surface were investigated at 300 in dry oxygen with a pressure of 133 Pa. It was found that the SiO2/Si interfacial transition layer is formed in three steps characterized by three different oxidation rates.