There is provided a nitride crystal substrate constituted by group-III nitride crystal, containing n-type impurities, with an absorption coefficient ? being approximately expressed by equation (1) by a least squares method in a wavelength range of at least 1 ?m or more and 3.3 ?m or less. $\begin{array}{cc}?=N_{e}K{?}^a\left(\mathrm{where}1.5?{10}^{-19}?K?6.?{10}^{-19},a=3\right),& \left(1\right)\end{array}$ here, a wavelength is ? (?m), an absorption coefficient of the nitride crystal substrate at 27? C. is ? (cm.sup.?1), a carrier concentration in the nitride crystal substrate is N.sub.e (cm.sup.?3), and K and a are constants, wherein an error of an actually measured absorption coefficient with respect to the absorption coefficient ? obtained from equation (1) at a wavelength of 2 ?m is within +0.1?, and in a reflection spectrum measured by irradiating the nitride crystal substrate with infrared light, there is no peak with a peak top within a wavenumber range of 1,200 cm.sup.?1 or more and 1,500 cm.sup.?1 or less.

Embodiments of the present disclosure include techniques related to techniques for processing materials for manufacture of group-III metal nitride and gallium based substrates. More specifically, embodiments of the disclosure include techniques for growing large area substrates using a combination of processing techniques. Merely by way of example, the disclosure can be applied to growing crystals of GaN, AlN, InN, InGaN, AlGaN, and AlInGaN, and others for manufacture of bulk or patterned substrates. Such bulk or patterned substrates can be used for a variety of applications including optoelectronic and electronic devices, lasers, light emitting diodes, solar cells, photo electrochemical water splitting and hydrogen generation, photodetectors, integrated circuits, and transistors, and others.

A method and apparatus for producing a Group III nitride in which the thermal decomposition of the nitrogen element-containing gas is suppressed to enhance the productivity. The method for producing a Group III nitride crystal, comprising: reacting an oxide or a metal of a Group III element under a heated atmosphere to form a compound gas of the Group III element; mixing a nitrogen element-containing gas at a temperature that is lower than that of the compound gas, with the compound gas; and reacting the nitrogen element-containing gas with the compound gas to form a Group III nitride crystal.

The invention provides, in one instance, a group III nitride wafer sliced from a group III nitride ingot, polished to remove the surface damage layer and tested with x-ray diffraction. The x-ray incident beam is irradiated at an angle less than 15 degree and diffraction peak intensity is evaluated. The group III nitride wafer passing this test has sufficient surface quality for device fabrication. The invention also provides, in one instance, a method of producing group III nitride wafer by slicing a group III nitride ingot, polishing at least one surface of the wafer, and testing the surface quality with x-ray diffraction having an incident beam angle less than 15 degree to the surface. The invention also provides, in an instance, a test method for testing the surface quality of group III nitride wafers using x-ray diffraction having an incident beam angle less than 15 degree to the surface.

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

Systems and methods for MBE growing of group-III Nitride alloys, comprising establishing an average reaction temperature range from about 250 C to about 850 C; introducing a nitrogen flux at a nitrogen flow rate; introducing a first metal flux at a first metal flow rate; and periodically stopping and restarting the first metal flux according to a first flow duty cycle. According to another embodiment, the system comprises a nitrogen source that provides nitrogen at a nitrogen flow rate, and, a first metal source comprising a first metal effusion cell that provides a first metal at a first metal flow rate, and a first metal shutter that periodically opens and closes according to a first flow duty cycle to abate and recommence the flow of the first metal from the first metal source. Produced alloys include AlN, InN, GaN, InGaN, and AlInGaN.

The present application provides nitride semiconductor nanoparticles, for example nanocrystals, made from a new composition of matter in the form of a novel compound semiconductor family of the type group II-III-N, for example ZnGaN, ZnInN, ZnInGaN, ZnAlN, ZnAlGaN, ZnAlInN and ZnAlGaInN. This type of compound semiconductor nanocrystal is not previously known in the prior art. The invention also discloses II-N semiconductor nanocrystals, for example ZnN nanocrystals, which are a subgroup of the group II-III-N semiconductor nanocrystals. The composition and size of the new and novel II-III-N compound semiconductor nanocrystals can be controlled in order to tailor their band-gap and light emission properties. Efficient light emission in the ultraviolet-visible-infrared wavelength range is demonstrated. The products of this invention are useful as constituents of optoelectronic devices such as solar cells, light emitting diodes, laser diodes and as a light emitting phosphor material for LEDs and emissive EL displays.

Systems and methods for MBE growing of group-III Nitride alloys, comprising establishing an average reaction temperature range from about 250 C to about 850 C; introducing a nitrogen flux at a nitrogen flow rate; introducing a first metal flux at a first metal flow rate; and periodically stopping and restarting the first metal flux according to a first flow duty cycle. According to another embodiment, the system comprises a nitrogen source that provides nitrogen at a nitrogen flow rate, and, a first metal source comprising a first metal effusion cell that provides a first metal at a first metal flow rate, and a first metal shutter that periodically opens and closes according to a first flow duty cycle to abate and recommence the flow of the first metal from the first metal source. Produced alloys include AN, InN, GaN, InGaN, and AlInGaN.

A method of producing nitride nanoparticles comprises reacting at least one organometallic compound, for example an alkyl metal, with at least one source of nitrogen. The reaction may involve one or more liquid phase organometallic compounds, or may involve one or more liquid phase organometallic compounds dissolved in a solvent or solvent mixture. The reaction constituents may be heated to a desired reaction temperature (for example in the range 40 C. to 300 C.).

In wireless communications, many radio frequency bands are used. For each frequency band, there are two frequencies one for transmit and the other for receive. As the band widths are small and separation between adjacent bands is also small, many band pass filters with different band pass frequencies are required for each communication unit such as mobile handset. The present invention provides frequency tunable film bulk acoustic resonators (FBAR) with different structures. Thin film biasing resistors are integrated into the FBAR structure for DC biasing and RF isolation. A plurality of the present tunable FBARs are connected to form microwave filters with tunable bandpass frequencies and oscillators with selectable resonating frequencies by varying DC biasing voltages to the resonators.