Abstract: Disclosed are a diboride single crystal substrate which has a cleavage plane as same as that of a nitride compound semiconductor and is electrically conductive; a semiconductor laser diode and a semiconductor device using such a substrate and methods of their manufacture wherein the substrate is a single crystal substrate 1 of diboride XB2 (where X is either Zr or Ti) which is facially oriented in a (0001) plane 2 and has a thickness of 0.1 mm or less. The substrate 1 is permitted cleaving and splitting along a (10-10) plane 4 with ease. Using this substrate to form a semiconductor laser diode of a nitride compound, a vertical structure device can be realized. Resonant planes of a semiconductor laser diode with a minimum of loss can be fabricated by splitting the device in a direction parallel to the (10-10) plane. A method of manufacture that eliminates a margin of cutting is also realized.

Abstract: Disclosed are a diboride single crystal substrate which has a cleavage plane as same as that of a nitride compound semiconductor and is electrically conductive; a semiconductor laser diode and a semiconductor device using such a substrate and methods of their manufacture wherein the substrate is a single crystal substrate 1 of diboride XB2 (where X is either Zr or Ti) which is facially oriented in a (0001) plane 2 and has a thickness of 0.1 mm or less. The substrate 1 is permitted cleaving and splitting along a (10-10) plane 4 with ease. Using this substrate to form a semiconductor laser diode of a nitride compound, a vertical structure device can be realized. Resonant planes of a semiconductor laser diode with a minimum of loss can be fabricated by splitting the device in a direction parallel to the (10-10) plane. A method of manufacture that eliminates a margin of cutting is also realized.

Abstract: A substrate for forming a semiconducting layer is provided to grow the semiconducting layer on a major surface thereof, wherein the substrate comprises a single crystal of a chemical formula of XB2 where X contains one of Ti and Zr and the major surface may preferably be substantially parallel to plane (0001) of the single crystal because the plane (0001) of the boride substrate is highly coherent to the lattices of GaN and AlN layers grown eptaxially on the substrate. The single crystal of the substrate may be a solid solution containing impurities of not more than 5%, wherein at least one of the impurities is one selected from Cr, Hf, V, Ta and Nb. Further, a semiconductor device includes the substrate of a single crystal of a chemical formula of XB2 and at least one semiconducting layer which is grown epitaxially on the substrate, the semiconducting layer including a nitride semiconductor of a chemical formula of ZN where Z is one of gallium, aluminum and indium and boron.

Abstract: A substrate for forming a semiconducting layeris provided to grow the semiconducting layer on a major surface thereof, wherein the substrate comprises a single crystal of a chemical formula of XB2 where X contains one of Ti and Zr and the major surface may preferably be substantially parallel to plane (0001) of the single crystal because the plane (0001) of the boride substrate is highly coherent to the lattices of GaN and AlN layers grown eptaxially on the substrate. The single crystal of the substrate may be a solid solution containing impurities of not more than 5%, wherein at least one of the impurities is one selected from Cr, Hf, V, Ta and Nb. Further, a semiconductor device includes the substrate of a single crystal of a chemical formula of XB2 and at least one semiconducting layer which is grown epitaxially on the substrate, the semiconducting layer including a nitride semiconductor of a chemical formula of ZN where Z is one of gallium, aluminum and indium and boron.

Abstract: A rare earth hexaboride electron-emitting material of the formula ReB.sub.6+x, wherein Re is La, Ce or (La+Ce), and 0.05.ltoreq.x.ltoreq.0.20.

Abstract: A rare earth hexaboride electron-emitting material of the formula ReB.sub.6+x, wherein Re is La, Ce or (La+Ce) and 0.05.ltoreq.x.ltoreq.0.20.

Abstract: A method of automatically growing a single crystal by using a floating-zone method in which radio-frequency induction heating is utilized, wherein the shape of molten zone of a sintered rod material is judged by comparing an anode voltage in a radio-frequency oscillation tube with a radio-frequency current, or a change in the shape of molten zone is judged depending of a change in a radio-frequency current during the growth of the sintered rod material, and power for heating is controlled on the basis of the judgement.

Abstract: It is an object of the present invention to obtain a high quality YB66 crystal by lowering the temperature of the molten zone and growing a crystal by deposition growth under an incongruent condition. A method for preparing a yttrium 66 boride crystal by the floating zone method by use of a YB66 polycrystalline rod. A YB66 crystal having a composition with an atomic ratio B/Y within a range of from 50 to 75, is grown under such conditions that the melt has a composition (an atomic ratio B/Y) different from the raw YB66 polycrystalline rod and the growing YB66 crystal, and that an equilibrium is maintained at the growth interface. When the atomic ratio B/Y of the starting material is within the range of from 50 to 62 and the atomic ratio B/Y of the melt is within the range of from 40 to 62, it is possible to attain the atomic ratio B/Y of the growing crystal within the range of from 50 to 62.

Abstract: The present invention relates to a lanthanum boride type single crystal having the chemical formula (La.sub.1-x M.sub.x)B.sub.6 (0.01.ltoreq.x.ltoreq.0.50) wherein M is at least one rare earth element selected from the group consisting of Ce, Pr, Nd, Sm and Gd, and further relates to a method for growing a lanthanum boride type single crystal by fusion method, which comprises using a lanthanum boride starting material containing from 1 to 50 mol % of at least one rare earth boride selected from the group consisting of CeB.sub.6, PrB.sub.6, NdB.sub.6, SmB.sub.6 and GdB.sub.6.