Sumitomo Electric Industries, Limited

Shin-ichi Akai

Hideki Mori

Takashi Shimoda

Shin-ichi Iguchi

Yasuhiro Nishida

Kazuhisa Matsumoto

Keiichiro Fujita

Masami Sasaki

Nobuo Takahashi

Katsunosuke Aoyagi

Takashi Suzuki

GaAs single crystals doped with boron and having a lowered dislocation density are grown from a GaAs melt covered with B.sub.2 O.sub.3 melt as a liquid encapsulant. The method comprises using a crucible made of a material selected from the group consisting of PBN, AlN and Al.sub.2 O.sub.3 as a crucible for holding the GaAs melt, adding 0.25 to 0.95 atomic percent of boron to the GaAs melt under conditions such that the residual oxygen quantity is at most 5.times.10.sup.-2 mole percent to the GaAs melt, and thereby adjusting the concentration of boron in the grown crystal to 2.times.10.sup.18 to 1.times.10.sup.19 atoms per cm.sup.3. The method is applied to an LE-VB method and an LE-VGF method as well as an LEC method.

Method of producing GaAs single crystals doped with boron

Gallium phosphide single crystals with low defect density which are manufactured by the liquid encapsulation Czochralski pulling method and which are characterized in that they are doped or not doped with at least one kind of dopant which is electrically active in gallium phosphide and are so doped as to have at least one dopant such as boron or some other strongly reducing impurity which has a reducing activity equal to or greater than that of boron remain in the crystals in a quantity not less than 1.times.10.sup.17 cm.sup.-3 and the sum of dislocation etch pit density and small conical etch pit density of the surface (111)B which has been subjected to etching for 3 to 5 minutes with RC etchant at a temperature of 65.degree. C..about.75.degree. C. after removing the mechanically damaged layer on the surface does not exceed 1.times.10.sup.5 cm.sup.-2, and a method of manufacturing the crystals.

Method of manufacturing gallium phosphide single crystals with low

In a semi-insulating gallium arsenide single crystal containing at least one of deep acceptor impurities and at least one of deep donor impurities and having a resistivity of at least about 10.sup.6 .OMEGA..multidot.cm at 300 .degree. K., (1) at least one of the deep donor impurities is oxygen, the oxygen concentration in the single crystal being at least about 4.times.10.sup.16 cm.sup.-3, while the silicon concentration in the single crystal being simultaneously at most about 2.times.10.sup.15 cm.sup.-3, (2) at least one of the deep acceptor impurities is chromium, the chromium concentration in the single crystal being within a range of about 3.times.10.sup.15 to about 3.times.10.sup.17 cm.sup.-3 and (3) at least one of tellurium, tin, selenium and sulfur is contained as another shallow donor impurity than silicon so to satisfy the relationship of N.sub.AA &gt;N.sub.D -N.sub.A &gt;-N.sub.DD wherein N.sub.AA represents the sum of concentrations of the deep acceptor impurities including chromium, N.sub.DD represents the sum of concentrations of the deep donor impurities including oxygen, N.sub.D represents the sum of concentrations of the shallow donor impurities including electrically active lattice defects and N.sub.A represents the sum of concentrations of the shallow acceptor impurities including electrically active lattice defects.

Semi-insulating gallium arsenide single crystal

A plurality of single-crystal epitaxial layers of semiconductors are simultaneously grown on a plurality of suitable substrates from the liquid phase by a method which includes the step of consecutively, and at times simultaneously, supplying small portions of liquid solution from a solution reservoir onto all the surfaces of the substrates in a plurality of wells which are provided on a surface of a rotatable circular lower plate so that epitaxial growth can be simultaneously carried out in all wells. The solution reservoir is positioned on a radius of the lower plate on which a circular upper plate is also provided in a non-rotatable state relative to the solution reservoir. Small portions of liquid solution are supplied by rotating the lower plate relative to the upper plate and the solution reservoir, and constrained in shape and volume which are adjusted by the upper plate and the wells. The composition and doping level of epitaxial layers are controlled through vapor-liquid communication.

Method for growing epitaxial layers on multiple semiconductor wafers

Single-crystal epitaxial layers of compound semiconductors or mixed semiconductors are grown on suitable substrates from the liquid phase, which consists of a molten metallic solvent dissolving a source material of the semiconductors, and within which the temperature gradient is produced so that in a high temperature region of the liquid solution a solid source material is dissolving into the liquid solution with at least a portion of the solid source material always at an undissolved state and in a low temperature region of the liquid solution an epitaxial layer is depositing onto the substrate, the temperatures in the liquid solution being kept constant during the epitaxial growth. Each substrate is positioned in one of a number of slots which are provided in the upper surface of a slider and it is successively transferred with the slider to contact with the liquid solution. The composition and/or the doping level of each epitaxial layer are controlled by the composition and/or the doping level of the solid source material which is selected from a pre-synthesized material, i.e., a solid film produced on the liquid solution by supersaturation and a film deposited on the liquid solution from the vapor phase.

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Osaka, Japan

Shin-ichi Akai