サファイア基板上にSiをエピタキシャル成長させたSOS (Si on Sapphire)の成長において,ヘテロエピタキシャル成長に起因する諸問題を解決するため,非晶質Siを非常に薄く堆積させてから,気相成長を行うという界面制御プロセスについて述べる.そのため,まずSiとサファイア界面の様子を解説し,界面制御プロセスとの関係を明らかにする.スパッタ法と紫外光励起法を用いた方法について説明し,この方法で得られる成長膜の特徴と成長機構について述べる.この方法は,他のヘテロエピタキシャル成長にも共通するところが多く,Si/CaF2系についても触れる.
We have measured surface extended electron-energy loss fine structure (SEELFS) and extended appearance potential fine structure (EAPFS) on evaporated Ti film, amorphous TiFe film and polycrystalline graphite and studied their surface structures. In the case of titanium, the result of SEELFS for the final state angular momentum ι=2 is in good agreement with the nearestneighbour atomic spacing of bulk titanium. This result shows that the dipole selection rule is satisfied. The analysis of EAPFS with ι=2 also gives a reasonable atomic spacing and indicates that the excitation to ι=2 is dominant though the dipole selection rule is not generally valid for EAPFS. Nearest-neighbour atomic spacing obtained from SEELFS and EAPFS are 0.293±0.006 nm and 0.287±0.005 nm, respectively. We applied the same analysis to the SEELFS and EAPFS of amorphous TiFe film, assuming the dipole selection rule, and obtained the nearest-neighbour atomic spacing of 0.253±0.005 nm from SEELFS and 0.257±0.004 nm from EAPFS. In the case of graphite, the analysis of SEELFS and EAPFS with ι=1 gives C-C distance of 0.136±0.005 nm and 0.134±0.004 nm, respectively.
During the development of a synchroscan streak tube, a multipactor discharge which much increases background noise on the output screen has occurred. The relationships between the discharge and the operating conditions, the manufacturing process of the tube and the tube construction have been investigated. It has been found that the discharge can be prevented by adding a shield electrode near the deflection electrode. The developed tube is compact and easy to operate because it has low accelerating voltage of 5 kV and high deflection sensitivity of 50 mm/kVp-p. The spectral response covers over a range from 200 nm to 850 nm. It can be operated over wide sweeping frequencies ranging from 80 MHz to 160 MHz and the temporal resolution of _??_8ps has been obtained at 80 MHz. Moreover, it is very highly sensitive because a microchannel plate is incorporated and high speed gating is available by switching the applied voltage of the plate.
A new theory for analyzing the three dimensional imaging characteristics of optical microscopes is proposed. This theory is based on the first-order Born approximation, including diffraction limitation, the dispersion equation of optical wave, and Bragg condition. 3-D spatial-frequency bands are derived by the proposed theory for the conventional microscopes of coherent, incoherent, and fluorescence types. For the confocal microscopes of transmission and fluorescence types, precise 3-D OTFs are derived. The following results are found by examining the derived OTFs: 1) A confocal transmission microscope has the same 3-D imaging characteristic as the conventional incoherent microscope. 2) The longitudinal resolving power of a confocal fluorescence microscope is higher than any type of conventional or confocal microscopes. This microscope does not have the “missing cone” in its 3-D OTF space. 3) The lateral spatial-frequency band of a confocal fluorescence microscope is twice as wide as a fluorescence microscope with uniform illumination.
The transmission character of the cesium vapor blocking filter for the high spectral resolution lidar was investigated using a narrow band dye laser pumped by an excimer laser. The dependence of the measured absorption band width of the filter on the operational temperature agrees with the theoretical calculation. The result shows that the secium vapor filter has the spectral charactor most suitable for the high spectral resolution lidar.