Michihiro Miyauchi

Growth of Aluminum Nitride Films on Silicon by Electron-Cyclotron-Resonance-Assisted Molecular Beam Epitaxy

Aluminum nitride thin films have been prepared on silicon substrates by electron-cyclotron-resonance plasma-assisted molecular beam epitaxy (ECR-MBE). Epitaxial AlN films have been obtained by Al evaporation and 250 eV nitrogen ion irradiation on a clean Si surface at 700°C. AlN films with two kinds of crystal orientations were grown epitaxially on Si(111). The dominant one is AlN (0001)//Si(111); AlN[010]//Si[11] and the another one is AlN(010)//Si(111); AlN[0001]//Si[11].

Raman microprobe study of recrystallization in ion‐implanted and laser‐annealed polycrystalline silicon

Implantation‐amorphized polycrystalline silicon layers which are directly deposited on single‐crystal Si are annealed by a scanning cw laser. The crystallinity of the annealed layers has been examined by a Raman microprobe in combination with polarization measurements. The Raman spectra measured for the specimens annealed at various power levels reveal that the polysilicon layer is regrown liquid epitaxially and is transformed into single crystal at high annealing power levels and that the regrowth at lower power levels is governed by the mixture of solid and liquid epitaxial processes. It is found that for specimens annealed at high power levels the tensile stress in the annealed layer is relaxed to a certain extent, though the weak residual strain still remains. The Raman microprobe spectra from the boundary reigon between the annealed and amorphous layers are recorded by making the probe laser beam traverse the boundary region. This technique enables us to investigate the variation in crystallinity and...

Residual Strain in Single Crystalline Germanium Islands on Insulator

Residual strain in single crystalline germanium islands, recrystallized by zone melting, on SiO2 substrates has been investigated by Raman microprobe measurements with a spatial resolution of 5 µm. It was found that strain of 3.0×10-3–6.0×10-3, corresponding to local tensile stress of 2.3 to 4.6 kbar, remained in single crystalline germanium islands after zone melting recrystallization.

Characterization of ion implanted and laser annealed polycrystalline Si by a Raman microprobe

The Raman frequency, intensity, and bandwidth of the ion implanted and cw laser annealed polycrystalline Si films have been measured by the Raman microprobe with a spatial resolution of 1 μm. The crystallinity estimated from these quantities changes drastically at the boundary region between the annealed and amorphous regions which is 6∼8 μm in width. The polarization measurement of the Raman scattering enables the estimation of grain size of the annealed region.

Raman image measurements of laser-recrystallized polycrystalline Si films by a scanning Raman microprobe

We have measured two-dimensional Raman intensity images of laser-recrystallized polycrystalline silicon islands on insulators by a scanning Raman microprobe. It is found that crystallites with about ten µm size grow along the scanning direction of an annealing laser. The crystallographic orientations of the crystallites have been determined by Raman microprobe polarization measurements.

Incorporation of Constituent Atoms of Transparent Conductive Films into Hydrogenated Amorphous Silicon via Gas Phase

Thin films of hydrogenated amorphous silicon (a-Si:H) were deposited on single-crystal silicon (c-Si) surrounded by ITO or SnO2 films as a function of substrate temperature. It was found that In atoms are incorporated in the a-Si:H films on c-Si while Sn atoms are hardly detected. The concentrations of In atoms in the a-Si:H films on c-Si and ITO films are in the range of 1017–1018/cm3 and 4×1017–1020/cm3, respectively, in the temperature range studied (room temperature-280°C. Annealing steps subsequent to the a-Si:H deposition without substrate heating resulted in a slight change in the concentration profile of In atoms. It is deduced that the In atoms resulting from the reduction of ITO films by SiH4-H2 plasma are incorporated into the a-Si:H films on c-Si via a gas phase. The gas-phase doping is markedly dependent upon the atomic species and deposition temperature. This may also be one of the important mechanisms responsible for the In incorporation into a-Si:H films on ITO films.

Cathodoluminescence Measurement of Surfaces in Reflection High-Energy Electron Diffraction Experiments

A new surface analysis system comprising by a reflection high-energy electron diffraction (RHEED) apparatus combined with a cathodoluminescence (CL) detector has been developed. In this method, the luminescence is mainly radiated from the region within a few tens of nanometers below the surface due to the very shallow penetration of the electron beam. This enhancement of surface sensitivity has been demonstrated using bare and Au-coated sapphire (0001) wafers. The CL spectra varied with changing Au thickness on the order of nm, as well as with changing incident angle.

Characterization of Gallium Arsenide Layers on Insulators with Germanium Interface Islands

GaAs layers were grown by molecular beam epitaxy on single-crystal Ge-island layers, grown by zone melting recrystallization with SiO2 capping layers, on the thermal oxide of Si wafers.