A conductive C-plane GaN substrate has a resistivity of 2?10.sup.?2 ?.Math.cm or less or an n-type carrier concentration of 1?10.sup.18 cm.sup.?3 or more at room temperature. At least one virtual line segment with a length of 40 mm can be drawn at least on one main surface of the substrate. The line segment satisfies at least one of the following conditions (A1) and (B1): (A1) when an XRC of (004) reflection is measured at 1 mm intervals on the line segment, a maximum value of XRC-FWHMs across all measurement points is less than 30 arcsec; and (B1) when an XRC of the (004) reflection is measured at 1 mm intervals on the line segment, a difference between maximum and minimum values of XRC peak angles across all the measurement points is less than 0.2?.

A gallium-containing nitride crystals are disclosed, comprising: a top surface having a crystallographic orientation within about 5 degrees of a plane selected from a (0001)+c-plane and a (000-1)c-plane; a substantially wurtzite structure; n-type electronic properties; an impurity concentration of hydrogen greater than about 510.sup.17 cm.sup.3, an impurity concentration of oxygen between about 210.sup.17 cm.sup.3 and about 110.sup.20 cm.sup.3, an [H]/[O] ratio of at least 0.3; an impurity concentration of at least one of Li, Na, K, Rb, Cs, Ca, F, and Cl greater than about 110.sup.16 cm.sup.3, a compensation ratio between about 1.0 and about 4.0; an absorbance per unit thickness of at least 0.01 cm.sup.1 at wavenumbers of approximately 3175 cm.sup.1, 3164 cm.sup.1, and 3150 cm.sup.1, and wherein, at wavenumbers between about 3200 cm.sup.1 and about 3400 cm.sup.1 and between about 3075 cm.sup.1 and about 3125 cm.sup.1, said gallium-containing nitride crystal is essentially free of infrared absorption peaks having an absorbance per unit thickness greater than 10% of the absorbance per unit thickness at 3175 cm.

A first object of the present invention is to provide a method for efficiently growing a nitride single crystal even under low pressure conditions. The present invention relates to a method for producing a nitride single crystal, comprising growing a nitride crystal on the surface of a seed crystal having a hexagonal crystal structure by setting a pressure in a reaction vessel having the seed crystal, a nitrogen-containing solvent, a mineralizer containing a fluorine atom, and a raw material placed therein to 5 to 200 MPa and performing control so that the nitrogen-containing solvent is in at least either a supercritical state or a subcritical state.

An object is to provide a nonpolar or semipolar GaN substrate having improved size and crystal quality. A self-standing GaN substrate has an angle between the normal of the principal surface and an m-axis of 0 degrees or more and 20 degrees or less, wherein: the size of the projected image in a c-axis direction when the principal surface is vertically projected on an M-plane is 10 mm or more; and when an a-axis length is measured on an intersection line between the principal surface and an A-plane, a low distortion section with a section length of 6 mm or more and with an a-axis length variation within the section of 10.010.sup.5 or less is observed.

The present invention relates to the field of field emission lighting, and specifically to a method for forming a field emission cathode. The method comprises arranging a growth substrate in a growth solution comprising a Zn-based growth agent, the growth solution having a pre-defined pH-value at room temperature; increasing the pH value of the growth solution to reach a nucleation phase; upon increasing the pH of the solution nucleation starts. The growth phase is then entered by decreasing the pH. The length of the nanorods is determined by the growth time. The process is terminated by increasing the pH to form sharp tips. The invention also relates to a structure for such a field emission cathode and to a lighting arrangement comprising the field emission cathode.

A gallium-containing nitride crystals are disclosed, comprising: a top surface having a crystallographic orientation within about 5 degrees of a plane selected from a (0001) +c-plane and a (000-1) ?c-plane; a substantially wurtzite structure; n-type electronic properties; an impurity concentration of hydrogen greater than about 5?10.sup.17 cm.sup.?3; an impurity concentration of oxygen between about 2?10.sup.17 cm.sup.?3 and about 1?10.sup.20 cm.sup.?3; an [H]/[O] ratio of at least 0.3; an impurity concentration of at least one of Li, Na, K, Rb, Cs, Ca, F, and Cl greater than about 1?10.sup.16 cm.sup.?3; a compensation ratio between about 1.0 and about 4.0; an absorbance per unit thickness of at least 0.01 cm.sup.?1 at wavenumbers of approximately 3175 cm.sup.?1, 3164 cm.sup.?1, and 3150 cm.sup.?1; and wherein, at wavenumbers between about 3200 cm.sup.?1 and about 3400 cm.sup.?1 and between about 3075 cm.sup.?1 and about 3125 cm.sup.?1, said gallium-containing nitride crystal is essentially free of infrared absorption peaks having an absorbance per unit thickness greater than 10% of the absorbance per unit thickness at 3175 cm.

An object is to provide a nonpolar or semipolar GaN substrate having improved size and crystal quality. A self-standing GaN substrate has an angle between the normal of the principal surface and an m-axis of 0 degrees or more and 20 degrees or less, wherein: the size of the projected image in a c-axis direction when the principal surface is vertically projected on an M-plane is 10 mm or more; and when an a-axis length is measured on an intersection line between the principal surface and an A-plane, a low distortion section with a section length of 6 mm or more and with an a-axis length variation within the section of 10.010.sup.5 or less is observed.

Techniques for processing materials in supercritical fluids including processing in a capsule disposed within a high-pressure apparatus enclosure are disclosed. The disclosed techniques are useful for growing crystals of GaN, AlN, InN, and their alloys, including InGaN, AlGaN, and AlInGaN for the manufacture of bulk or patterned substrates, which in turn can be used to make optoelectronic devices, lasers, light emitting diodes, solar cells, photoelectrochemical water splitting and hydrogen generation devices, photodetectors, integrated circuits, and transistors.

Embodiments of the disclosure include a thermal insulation structure, comprising a plurality of stacked layers that include a first layer and a second layer. The first layer includes a first surface, a second surface, disposed opposite of the first surface, and a plurality of perforations extending between the first surface and the second surface, wherein the plurality of perforations comprise a first pattern of two or more perforations that form a patterned in a first direction that is parallel to the first surface. The second layer includes a third surface, wherein the third surface is in contact with the second surface of the first layer, a fourth surface, disposed opposite of the third surface, and a plurality of perforations extending between the third surface and the fourth surface, wherein the plurality of perforations comprise a second pattern of two or more perforations that form a pattern in the first direction that is parallel to the third surface.

Embodiments of disclosure include an apparatus for high-temperature crystal growth. The apparatus can include a pressure vessel having a capsule that has an interior surface that defines an internal capsule volume, a fill tube that comprises an outer surface and an inner surface, wherein an interior fill tube volume defined by the inner surface is in fluid communication with the internal capsule volume of the capsule, a sleeve axially surrounding the outer surface of the fill tube, wherein the sleeve is configured to support the outer surface of the fill tube, along the length of the fill tube, during a high-temperature crystal growth process, and a manifold comprising an interior manifold volume that is in fluid communication with the interior fill tube volume of the fill tube.