Abstract: A luminous efficiency is estimated by obtaining a life time a of few carriers controlling the luminous efficiency. An estimation method inadiates pulsed laser light for exciting carriers in a light emitting layer by a co-focal point optical system, at a specified position of the light emitting layer of a light emitting element formed on a surface of a wafer. A life time is obtained by detecting the fluorescent light emitted from the specified position in the light emitting layer corresponding to an irradiation of the pulsed laser light and by observing a change of the fluorescent light with lapse of a time. A luminous efficiency is estimated at the specified position in the light emitting layer from the life time on the basis of a correlation of a life time and a luminous efficiency previously obtained, thereby enabling an estimation of the light emitting element at a wafer stage without destroying the wafer and without contact therewith.

Abstract: A method of manufacturing compound semiconductor crystals, comprising the steps of, providing a compound semiconductor melt in a crucible, said melt having a composition ratio which deviates from stoichiometry, pulling a compound semiconductor crystal from said crucible by using a seed crystal, and during the pulling step, adding to the melt a constitutional element of said compound semiconductor melt which is present in less than a stoichiometric amount, the element being added in a quantity sufficient to maintain said composition ratio of the first step. An apparatus for manufacturing compound semiconductor crystals is also provided.

Abstract: An apparatus has a crucible for containing a GaAs raw material melt and a B.sub.2 O.sub.3 liquid encapsulating material therein, a heat generator arranged around the crucible so as to be coaxial therewith, and a heat insulator assembly arranged around the heat generator to surround the heat generator and the crucible for the purpose of manufacturing a compound semiconductor single crystal by pulling it from the raw material melt in the crucible by the LEC method. In the heat insulator assembly of the apparatus of the above construction, an upper heat insulator, arranged above the crucible and having at its center a circular hole for receiving the single crystal being pulled, comprises a plurality of radially divided sector-shaped split members. The split members are sintered bodies having aluminum nitride (AlN) as a major constituent.

Abstract: A method for controlling the shape of a single crystal. The weight of a single crystal pulled by the Czochralski method is detected, to obtain a weight signal W. The weight signal W is differentiated over time, to obtain a differential signal dW/dt. Using the differential signal dW/dt, (A.multidot.dW/dt+B).theta. is computed, to obtain an operation signal f. A and B are parameters which are determined by predetermined manufacturing conditions of the Czochralski method, and .theta. is a preset growing angle of the single crystal. The operation signal f is integrated over time, to obtain an integral signal F. The integral signal F and the differential signal dW/dt are compared to obtain a deviation signal. The heating power supplied to the crucible is controlled by use of the deviation signal, to keep the growing angle of the single crystal constant.

Abstract: The invention provides a method and an apparatus for manufacturing single crystals wherein the weight of the single crystal pulled is measured by a weight detector. The measured weight is compared with a reference weight signal which is generated from a reference weight signal generator. A weight deviation signal representing a difference between these two signals is generated by a weight deviation detector. The weight deviation signal is differentiated by a first differentiation circuit and a differentiation output signal obtained is corrected for compensation for the buoyancy of the liquid encapsulant by a signal which is generated by a buoyancy correction signal generator. A corrected signal thus obtained is differentiated by a second differentiation circuit and is thereafter added to the corrected signal. The addition result is phase-compensated by a phase-compensating circuit. The phase-compensated signal is supplied to a heating control circuit.

Abstract: The invention provides a method and an apparatus for manufacturing single crystals wherein the weight of the single crystal pulled is measured by a weight detector. The measured weight is compared with a reference weight signal which is generated from a reference weight signal generator. A weight deviation signal representing a difference between these two signals is generated by a weight deviation detector. The weight deviation signal is differentiated by a first differentiation circuit and a differentiation output signal obtained is corrected for compensation for the buoyancy of the liquid encapsulant by a signal which is generated by a buoyancy correction signal generator. A corrected signal thus obtained is differentiated by a second differentiation circuit and is thereafter added to the corrected signal. The addition result is phase-compensated by a phase-compensating circuit. The phase-compensated signal is supplied to a heating control circuit.