Abstract: Provided is a single crystal with a hexagonal wurtzite structure which is useful as a substrate for various devices and has high purity and is uniform. The single crystal with a hexagonal wurtzite structures which is obtained by a crystal growth on at least an m-plane of a columnar seed crystal and represented by AX (A representing an electropositive element and X representing an electronegative element) is characterized in that a variation in the concentration of a metal other than the electropositive element A and having a concentration of 0.1 to 50 ppm is within 100%.

Abstract: A method of securing to an operating lever in the form of an elongated metal plate an operating button made of thermoplastic resin and including a mounting tongue of a generally tubular configuration having a hollow defined therein. An anchor perforation and a stopper pawl are first formed in the operating lever and the operating button is then temporarily mounted on the operating lever with the operating lever slid into the hollow of the mounting tongue until an abutment defined in the mounting tongue and positioned within the hollow is brought into engagement with the stopper pawl.

Abstract: A system for setting an analysis condition for a thermal analysis of a fluid inside an apparatus, wherein a gas flow-in temperature in the apparatus, a gas flow-in rate, and an apparatus outer wall temperature are set as critical conditions, the interior of the apparatus being under a high pressure atmosphere and heated by a heater, an analysis mesh shape, a pressure inside the apparatus and other values, and a heater power, are set as initial values, and a simulation is carried out so that an optimum operating condition is obtained, wherein the relationship between heater power by which a heater monitoring temperature is maintained at a constant value and a gas flow rate at the entrance while changing the apparatus internal pressure is obtained by a trial experiment, and the simulation is carried out by changing the gas flow rate at the entrance in accordance with the heater power and the gas flow rate at the entrance set as the initial value.

Abstract: A method for producing a semiconductor device comprises the steps of: preparing a III.sub.b -V.sub.b group compound single crystalline semiconductor substrate produced by a liquid encapsulated Czochralski process, the single crystalline semiconductor substrate having a carbon concentration of 1.times.10.sup.15 cm.sup.-3 or less, implanting conductive impurity ions into the single crystalline semiconductor substrate and then annealing, and a semiconductor device produced by this method.

Abstract: When the growth of a single crystalline III.sub.b -V.sub.b group compound is carried out employing the horizontal Bridgeman method or the gradient freeze method, it is likely that polycrystals will be grown, crystal defects will form, and the distribution of impurities will not be uniform, especially if the diameter of the single crystal is large. In the present invention, the cooling rate of the melt is controlled in an inconstant manner. Namely, crystal growth is interrupted at least once and/or the cooling rate at an earlier growth period is controlled at a high value. From 40 to 65% of the total melt crystallizes at the time when 30% of the total time required for growth has elapsed. The high yield of a single crystal is attained according to the present invention.