A crucible for growing a metal oxide single crystal is provided that can facilitate the balance between the thickness and the strength (hardness) of the constant diameter portion of the crucible and is capable of performing growth of a crystal having a large diameter. The crucible according to the present invention is a crucible for growing a metal oxide single crystal, including a reinforcing belt material provided on an outer periphery of a constant diameter portion of the crucible. It is possible that the crucible has an upper portion having a thickness that is smaller than a thickness of a lower portion of the crucible, and the upper portion of the crucible is the constant diameter portion.

A gallium oxide crystal manufacturing device includes a crucible to hold a gallium oxide source material therein, a crucible support that supports the crucible from below, a crucible support shaft that is connected to the crucible support from below and vertically movably supports the crucible and the crucible support, a tubular furnace core tube that surrounds the crucible, the crucible support and the crucible support shaft, a tubular furnace inner tube that surrounds the furnace core tube, and a resistive heating element including a heat-generating portion placed in a space between the furnace core tube and the furnace inner tube. Melting points of the furnace core tube and the furnace inner tube are not less than 1900° C. A thermal conductivity of a portion of the furnace core tube located directly next to the crucible in a radial direction thereof is higher than a thermal conductivity of the furnace inner tube.

A method is provided. The method includes providing an alignment structure at least partially defining a predetermined alignment pattern. The method also includes forming a solid crystal on the alignment structure. Crystal molecules of the solid crystal are aligned in the predetermined alignment pattern.

An optical element is provided. The optical element includes a solid crystal including crystal molecules aligned in a predetermined alignment pattern at least partially defined by an alignment structure.

Methods and wafers for low etch pit density, low slip line density, and low strain indium phosphide are disclosed and may include an indium phosphide single crystal wafer having a diameter of 4 inches or greater, having a measured etch pit density of less than 500 cm.sup.−2, and having fewer than 5 dislocations or slip lines as measured by x-ray diffraction imaging. The wafer may have a measured etch pit density of 200 cm.sup.−2 or less, or 100 cm.sup.−2 or less, or 10 cm.sup.−2 or less. The wafer may have a diameter of 6 inches or greater. An area of the wafer with a measured etch pit density of zero may at least 80% of the total area of the surface. An area of the wafer with a measured etch pit density of zero may be at least 90% of the total area of the surface.

A semi-insulating compound semiconductor substrate includes a semi-insulating compound semiconductor, the semi-insulating compound semiconductor substrate being configured such that, on a major plane having a plane orientation of (100), a standard deviation/average value of specific resistance measured at intervals of 0.1 mm along equivalent four directions in a <110> direction from a center of the major plane, and a standard deviation/average value of specific resistance measured at intervals of 0.1 mm along equivalent four directions in a <100> direction from the center of the major plane are each not more than 0.1.

A crucible includes an outer element and an inner element. The outer element includes a first portion that is horizontal at a bottom end of the crucible and a second portion that ascends radially outwardly from the bottom end of the crucible to a top end of the crucible at a first acute angle to a vertical axis. The inner element includes a conus with a cylinder at a base of the conus. The conus descends radially outwardly from the top end of the crucible to the bottom end of the crucible at a second acute angle to the vertical axis. The inner element includes a base portion of the cylinder attached to the first portion of the outer element using a sealant to form a hollow mold between an inner portion of the outer element and an outer portion of the inner element.

Methods and systems for low etch pit density 6 inch semi-insulating gallium arsenide wafers may include a semi-insulating gallium arsenide single crystal wafer having a diameter of 6 inches or greater without intentional dopants for reducing dislocation density, an etch pit density of less than 1000 cm.sup.2, and a resistivity of 110.sup.7 -cm or more. The wafer may have an optical absorption of less than 5 cm.sup.1 less than 4 cm.sup.1 or less than 3 cm.sup.1 at 940 nm wavelength. The wafer may have a carrier mobility of 3000 cm.sup.2/V-sec or higher. The wafer may have a thickness of 500 m or greater. Electronic devices may be formed on a first surface of the wafer. The wafer may have a carrier concentration of 1.110.sup.7 cm.sup.3 or less.

A heater comprises a plurality of zones with at least two zones having a variable power density gradient different from one another. The heater having zones of different variable power density gradients allows for controlling the heat output and temperature profile of the heater in one or more directions of the heater. The heater can be used, for example, to control the temperature profile in a vertical direction.

A method comprises: providing a spiral metallic workpiece having a cast structure associated with such spiral; and at least partially flattening the workpiece.