Undoped p-type CdTe was covered with dielectric films of Si3N4, SiO2, Al2O3 and AIN prepared by RF sputtering, reactive sputtering and CVD technique. When the samples were annealed at temperatures between 300-700°C for 5 hours in vacuum, a number of Cd atoms diffused from CdTe into the films at the interface. Cd vacancies in the CdTe surface layer caused by the out-diffusion of Cd resulted in an increase of carrier concentrations, and an enhanced diffusion of In atoms in CdTe. Such effects were not appreciable on the samples covered with Si3N4 films prepared by the CVD technique.
Using a microcomputer, an apparatus to construct automatically any desired surface of a pulverulent body by actuating the surface forming plate was manufactured for trial. This apparatus is advantageous in that it enables an optional surface to be formed easily and to process a number of informations simultaneously. Examples analyzed using this apparatus will also be reported.
In this paper, a nondestructive technique to measure the resistivity variation in a semiconductor wafer with a new photovoltaic method is described. The resistivity variation can be obtained by measuring the bulk photovoltage and photoconductivity caused by illuminating the semiconductor wafer surface. The authors proposed that the measuring method using the high frequency eddy current in the wafer is useful for the measurement of photoconductivity voltage, and analyzed it theoretically. Consequently, in this method, the resistivity variation can be determined independently of intensity and shape of the illuminated light and thickness of the wafer. For comparison, the resistivity variation of p and n type CZ-Si wafers was measured by both the new photovoltaic method and the four-point probe method, and experimental results of the two methods were in good agreement, with errors within a few per cent. It was confirmed that the resistivity striation of n type FZ-Si wafer can be well measured by this new photovoltaic method.
A DIAL (Differential Absorption Lidar) system for NO2 monitoring was developed using a flash-lamp pumped dye laser. It was used to measure NO2 concentration in a stack plume. Two wavelengths, resonant (463nm) and off-resonant (466nm) to the NO2 absorption, were switched every two seconds in the measurement ; this gave an accuracy of 0.03 ppm for NO2 concentration with 120m range resolution up to 500m by integrating signals for 4minutes. The sources of measurement error were investigated and the main source of error was shown to be the fluctuation of atmospheric aerosol concentration. It was pointed out that simultaneous measurement at two wavelengths should improve the accuracy of the measurement.
An automatic photometric ellipsometer is described, which has been designed for the study of the growth of evaporated films in the very early stages. The ellipsometer is of the rota-ting-phase-shifter type ; it is capable of determining the ellipsometric parameters with sensi-tivities, in typical cases, of δΔ=0.01°andδφ=0.01°, at every 20/24s interval of measure-ment (the speed can easily be increased by 50 times). It has a vacuum sample chamber equipped with a torsion microbalance, in which evaporation can be carried out at pressures equal to or below 10-4 Pa.
A review of polarization spectroscopy is presented. Polarization spectroscopy is a new method of Doppler-free laser spectroscopy with high sensitivity which is based on laser-induced optical activity in an absorbing gas. We describe the principle of high-resolution and high-sensitivity in polarization spectroscopy. This technique is applied to the observations of Stark and Zeeman effects and to the precise measurements of isotope shifts, Lamb shifts and fundamental physical constants.
Recent advances in generation of picosecond optical pulses using semiconductor lasers are reviewed. Various methods of generation making use of active and passive modelocking, pulse and sinusoidal current pumping (direct modulation), self-pulsation, Q-switching, and short pulse optical pumping have been examined. At present it is possible to obtain pulsewidth of 1 ps, pulse rate from single shot to several gigahertz, and peak power of a few watts both in the infrared and visible wavelength regions. One of the most important problems is to narrow the spectral width of the output pulses to transform limit. Several procedures related to this problem are discussed.
Experimental aspects of spectroscopic studies of large tokamak plasma are reviewed. Problems in the measurements of impurity contents and some possibility of ion temperature measurement using forbidden lines from highly ionized ions are discussed. Significance of charge exchange recombination process during neutral particle injection is also discussed. Relating to the impurity control, requirement for polychromator in the XUV region is em-phasized and some examples of gratings and multi-channel detector which are suitable for the XUV polychromator are given.