Showing papers on "Gallium nitride published in 1991"

GaN Growth Using GaN Buffer Layer

Abstract: High-quality gallium nitride (GaN) film was obtained for the first time using a GaN buffer layer on a sapphire substrate. An optically flat and smooth surface was obtained over a two-inch sapphire substrate. Hall measurement was performed on GaN films grown with a GaN buffer layer as a function of the thickness of the GaN buffer layer. For the GaN film grown with a 200 A-GaN buffer layer, the carrier concentration and Hall mobility were 4×1016/cm3 and 600 cm2/V·s, respectively, at room temperature. The values became 8×1015/cm3 and 1500 cm2/V·s at 77 K, respectively. These values of Hall mobility are the highest ever reported for GaN films. The Hall measurement shows that the optimum thickness of the GaN buffer layer is around 200 A.

High efficiency light emitting diodes from bipolar gallium nitride

Abstract: The invention is a method of growing intrinsic, substantially undoped single crystal gallium nitride with a donor concentration of 7×10 17 cm -3 or less. The method comprises introducing a source of nitrogen into a reaction chamber containing a growth surface while introducing a source of gallium into the same reaction chamber and while directing nitrogen atoms and gallium atoms to a growth surface upon which gallium nitride will grow. The method further comprises concurrently maintaining the growth surface at a temperature high enough to provide sufficient surface mobility to the gallium and nitrogen atoms that strike the growth surface to reach and move into proper lattice sites, thereby establishing good crystallinity, to establish an effective sticking coefficient, and to thereby grow an epitaxial layer of gallium nitride on the growth surface, but low enough for the partial pressure of nitrogen species in the reaction chamber to approach the equilibrium vapor pressure of those nitrogen species over gallium nitride under the other ambient conditions of the chamber to thereby minimize the loss of nitrogen from the gallium nitride and the nitrogen vacancies in the resulting epitaxial layer.

Epitaxial growth of zinc blende and wurtzitic gallium nitride thin films on (001) silicon

Abstract: Zinc blende and wurtzitic GaN films have been epitaxially grown onto (001)Si by electron cyclotron resonance microwave plasma‐assisted molecular beam epitaxy, using a two‐step growth process. In this process a thin buffer layer is grown at relatively low temperatures followed by a higher temperature growth of the rest of the film. GaN films grown on a single crystalline GaN buffer have the zinc blende structure, while those grown on a polycrystalline or amorphous buffer have the wurtzitic structure.

III-V nitrides for electronic and optoelectronic applications

Abstract: Recent developments in III-V nitride thin-film materials for electronic and optoelectronic applications are reviewed. The problems that are limiting the development of these materials and devices made from them are discussed. The properties of cubic boron nitride, aluminum nitride, gallium nitride, AlN/GaN solid solutions and heterostructures, and indium nitride are discussed. It is pointed out that the lack of a suitable substrate, with the possible exception of SiC for AlN, is a problem of considerable magnitude. This is compounded by the presence of shallow donor bands in GaN and InN which are apparently caused by N vacancies. The question of whether these vacancies occur (if they do) as a result of intrinsic or extrinsic (as a result of deposition) nonstoichiometry has not been answered. However, the recent advances in the fabrication of p-type GaN and a p-n junction light emitting diode via the electron beam stimulation of the Mg dopant are very encouraging and may considerably advance the technology of this material. This would indicate that self-compensation effects, similar to those observed in ZnO and ZnSe, may not be present in the III-V nitrides, since cubic BN (cBN) AlN and now GaN have been reportedly doped both n- and p-type. >

Epitaxial growth of cubic and hexagonal GaN on GaAs by gas‐source molecular‐beam epitaxy

Abstract: GaN epilayers were grown on GaAs substrates by gas‐source molecular‐beam‐epitaxy technique using dimethylhydrazine as a nitrogen source. It was found that cubic GaN grows on GaAs (001) surfaces epitaxially, while hexagonal GaN grows on GaAs (111) surfaces, from the analyses of x‐ray diffraction and reflection high‐energy electron diffraction patterns. Cathodoluminescence measurements suggested that the band‐gap energy of cubic GaN is around 0.37 eV larger than that of hexagonal GaN.

Light emitting semiconductor device using gallium nitride group compound

Abstract: Disclosed herein is a light-emitting semiconductor device that includes a gallium nitride compound semiconductor (AlxGa1-xN) comprising an n-layer and an i-layer, at least one of them being of a double layer structure. In one embodiment the n-layer has a double-layer structure including an n-layer of a low carrier concentration and an n+-layer of a high carrier concentration, the former being adjacent to the i-layer. In another embodiment, the i-layer has a double-layer structure including an iL-layer of a low impurity concentration containing p-type impurities in a comparatively low concentration and an iH-layer of a high impurity concentration containing p-type impurities in a comparatively high concentration, the former being adjacent to the n-layer. In still another embodiment, both of the n-layer and the i-layer have a double layer structure. Also disclosed is a method for producing the light-emitting semiconductor device which employs a vapor phase epitaxy. In one preferred method, an n-type gallium nitride compound semiconductor (AlxGA1-xN) having a controlled conductivity is produced from an organometallic compound by vapor phase epitaxy, by feeding a silicon-containing gas together with other raw material gases at a controlled mixing ratio.

Electroluminescent device of compound semiconductor with buffer layer

Abstract: An electroluminescent device of compound semiconductor including a semiconductor substrate, a buffer layer epitaxially grown on the semiconductor substrate and a luminescent layer epitaxially grown on the buffer layer, the substrate being formed from a single crystal of zinc sulfide, zinc selenide or a mixed crystal thereof, the luminescent layer being formed from aluminum nitride, indium nitride, gallium nitride or a mixed crystal of at least two of the nitrides.

Manufacture of p-type gallium nitride based compound semiconductor

Abstract: PURPOSE: To provide a method for manufacturing a p-type gallium nitride based compound semiconductor, by which a gallium nitride based compound semiconductor doped with a p-type impurity is made a p-type semiconductor having a low resistance and further, the value of the resistance is made uniform over the whole of its wafer independently of its film thickness and moreover, a light emitting element made of the compound semiconductor can have a double or single hetero-structure. CONSTITUTION: By a vapor growth method, a gallium nitride based compound semiconductor layer doped with a p-type impurity is formed, and thereafter, its annealing is performed at a temperature not lower than 400°C. However, it is more preferable that the annealing is performed in a pressurized atmosphere or performed by providing newly a cap layer on the gallium nitride based compound semiconductor. COPYRIGHT: (C)1993,JPO&Japio

Gallium nitride group semiconductor and light emitting diode comprising it and the process of producing the same

Abstract: A thin film of SiO 2 is patterned on an N layer consisting of N-type Al x Ga 1-x N (inclusive of x=0). Next, I-type Al x Ga 1-x N (inclusive of x=0) is selectively grown and the portion on the N layer grows into an I-layer consisting an active layer of a light emitting diode, and that on the SiO 2 thin film grows into a conductive layer. Electrodes are formed on the I-layer and conductive layer to constitute the light emitting diode. Also, on the surface a ({1120}) of a sapphire substrate, a buffer layer consisting of aluminum nitride is formed, onto which a gallium nitride group semiconductor is formed.

Structure Control of GaN Films Grown on (001) GaAs Substrates by GaAs Surface Pretreatments

Abstract: Two types of cubic and hexagonal GaN films were deposited on (001) GaAs substrates. The film structure proved to be controlled by GaAs pretreatments. By performing a N2H4 (hydrazine) pretreatment of GaAs substrates, the GaN films, which were otherwise hexagonal similarly to ordinary films on sapphire substrates, became cubic. A surface cubic nitride layer was found to be formed on the pretreated GaAs by a RHEED (reflection high-energy electron diffraction) observation, which is thought to be the substantial substrate for the following growth of a cubic GaN film.

Gallium nitride compound semiconductor light emission device

Abstract: PURPOSE:To improve the efficiency of light extraction and to suppress resistance components between electrodes. CONSTITUTION:A light emission device, having an n-layer 4 made of an n-type gallium nitride compound semiconductor (AlXGa1-XN; 0<=X

The Effect of Self Nucleation Layers on the Mocvd Growth of Gallium Nitride on Sapphire

Abstract: Self nucleation layers, nominally 50 nm in thickness, have been predeposited at temperatures in the range 600–1100°C and shown to markedly and uniformly improve the surface morphology of epitaxial layers of GaN on highly oriented (0001) sapphire substrates. However, the epitaxial relationship between the GaN film and the sapphire substrate and the electrical and optical properties of these films depend strongly on the temperature at which the nucleation layer is deposited. For example, growth on a nucleation layer deposited at 1100°C yields a film little changed In carrier concentration or mobility and exhibiting the epitaxial relationship [(O0 0 1)GaN// (O001)sapphire and (1010)GaN //(1120)sapphire] characteristic of films grown directly onto (0001) sapphire. In contrasT, film growth onto a nucleation layer deposited at 600°C results in a typically oriented but semi-insulating layer. Of particular interest, an intermediate growth temperature (850°C) yields GaN films that are unconventionally twinned and semiinsulating. The twinning is distinguished by GaN sublattices that are rotated ±10.9° with respect to the sapphire lattice, such that (3030)GaN //(4150)sapphire. While all films in this regime are twinned and highly resistive, examples of scattering from twins with unequal volumes and non-ideal rotation angle have been occasionally encountered. The results clearly demonstrate that the orientation of the nucleation layer governs the orientation and properties of the final film.

High pressure phase transition in gallium nitride

Abstract: Gullium nitrider GaN has been studied b, y Ramun scattering und x-ro ) absorpt ion spectroscopy under presrure up to 55 GPa. A phase t ransi t ion isobserved for the first lime at 47 GPa. lhr equal ion OJ state is determined with Bo +245 CPa using Bo51.The Criirreisen mode parameter of the four observedphonon modes are deduced. Le nifrure de gallium, GaN a ete etudie par diffusion Ramun etspeclroscopie d'absorpt ion X jusqu'a 55 GPa. Une transition de phase a ete observee pour la premiere jois a 41 CPa. En imposunt B0 =4 on peut reproduire I'equuiion d'e'fut avec B0=245 GPa. On en deduif les parametres de Cruneisen des quatre modes observes.

Method for cutting gallium nitride compound semiconductor wafer

Abstract: PURPOSE: To prevent generation of cracks and chippings in the surface of cutting, and to cut a gallium nitride compound semiconductor wafer into chips of desired shape and size at a high yield rate by grinding a sapphire substrate to optimize the thickness of the substrate CONSTITUTION: A gallium nitride compound semiconductor wafer, having a structure made by forming an N-type Ga x Al 1-x N (0≤X≤1) layer 2 on a sapphire substrate 1 and then forming a P-type or i-type Ga x Al 1-x N (0≤X≤1) layer 3 thereon, is cut into chips At this time, the sapphire substrate 1 is ground by a grinder to 100 to 250μm in thickness Further, the substrate side of the wafer or the side of the gallium nitride compound semiconductor, or both sides of them, are scribed and cut The scribing depth should by 10% or more of the thickness of the substrate 1, and the wafer is scribed in such a manner that the length of the shortest sides of the sapphire substrate of the cut chips is made longer than the thickness of the substrate 1 As a result, the cutting operation can be conducted at a high yield rate COPYRIGHT: (C)1993,JPO&Japio

Manufacture of gallium nitride compound semiconductor

Abstract: PURPOSE:To obtain an N-type GaN compound semiconductor in which its resistivity can be controlled by controlling mixture ratio of gas containing silicon to other raw gas. CONSTITUTION:A sapphire board 1 is vapor etched, an AlN buffer layer 2 is formed, a high carrier concentration layer 3 made of GaN is formed, and then an N type low carrier concentration layer 4 made of GaN is formed. When the layer 3 is formed by vapor growth, H2, NH3 as other raw gas and H2 in which TMG held at -25 deg.C are bubbled are fed to control flow rate of silane (SiH4) gas diluted with H2 is controlled as gas containing silicon.

High-efficiency UV and blue emitting devices prepared by MOVPE and low-energy electron-beam irradiation treatment

Abstract: The room teffiperature stiniulated emission near ultraviolet from ntype GaN film which was grown by MOVPE on a sapphire substrate is observed for the first time. The low energy electron beam irradiation treatment lowers the resistivity of Mgdoped GaN which tends to show p-type conduction and simultaneously enhances blue luminescence efficiency drastically. The pn junction LED shows strong both nearbandedge UV ends sion from nlayer and blue emission from player.

Growing method for crystal of gallium-aluminum nitride semiconductor

Abstract: PURPOSE: To improve the crystallizability of a laminated crystal by growing GaN films and AlN films alternately and separately and as multilayer film layers in such manner that GaXAl 1- XN seems to grown, and by stopping the lattice defect of gallium nitride compound to be grown on a sapphire substrate. CONSTITUTION: In the crystal growth method of gallium-aluminum nitride represented by general formula GaXAl 1- XN (0

Growing method for crystal of gallium nitride compound semiconductor and element thereof

Abstract: PURPOSE: To obtain a crystal of p-n junction gallium nitride compound semiconductor excellent in crystallizability. CONSTITUTION: When a buffer layer represented by general formula GaXAl 1- XN (0≤X≤1) and multilayer film layer, which is obtained when thin-film AlN layers and GaN layers are alternately grown in at least one layer laminated on the buffer layer, are grown on a substrate; the lattice defect of GaN is stopped by the multilayer film layer. COPYRIGHT: (C)1993,JPO&Japio

Gallium nitride thin film growing method

Abstract: PURPOSE:To obtain a GaN semiconductor thin film which is optimum for the optical element of ultraviolet rays to blue-colored region. CONSTITUTION:A GaN semiconductor thin film is manufactured by a film forming method with the vacuum device such as gas source MBE using nitrogen trifluoride as a nitrogen source. Accordingly, a flat thin film having excellent crystallizability can be obtained. Also, as carrier density can easily be controlled, this thin film is considered optimum as a semiconductor thin film for an optical element.

Light emitting semiconductor device

Abstract: In an electroluminescent device of compound semiconductor material including a semiconductor substrate (1), a buffer layer (2) epitaxially grown on the semiconductor substrate, and a luminescent layer (4) epitaxially grown on the buffer layer the substrate is formed from a single crystal of zinc sulfide, zinc selenide or a mixed crystal thereof, and the luminescent layer is formed from aluminum nitride, indium nitride, gallium nitride or a mixed crystal of at least two of the nitrides

Material for gallium nitride-based semiconductor light emitting element

Abstract: PURPOSE: To obtain a material for blue-ultraviolet band semiconductor light emitting element optimum for a display, an optical communication, etc., having a high light output efficiency. CONSTITUTION: A material for a gallium nitride-based semiconductor light emitting element having a structure in which with a surface 4 rotated at 9.2 degrees from a face R [plane (1,-1, 0, 2)] sapphire at a face R projection 3 of c-axis of the sapphire as a rotating axis, as a reference surface, a surface having an OFF angle being ±2 degrees or less is used as a substrate surface, and at least one type of gallium nitride-based semiconductor layer is laminated on the substrate, is manufactured by using a CBE melthod, etc., without using an AlN buffer layer, etc. This material for the element is flat in a thin film thickness, and a material for a blue-ultraviolet band semiconductor light emitting element adapted for a display, an optical communication, etc. COPYRIGHT: (C)1992,JPO&Japio

Band Structure and Refractive Index of Gallium Nitride Under Pressure

Abstract: Many physical properties of semiconductors can be scaled with such material parameters as atomic volume and ionicity. Theory proposed by Van Vechten [1] was built upon this fact, and gave qualitatively good picture of properties of a great number of tetrahedrally coordinated semiconductors, including directly also pressure effects. From this point of view it seems interesting to investigate pressure behavior f GaN, which is the most ionic semiconductor in the group (0.43 or 0.5 [1, 2] in the Phillips scale [3]) and has a very small atomic volume — about one half of that of GaAs. In the present work we measured the pressure dependence of absorption edge and refractive index (electronic dielectric constant). The band stucture of GaN is calculated from first principles the LMTO method within the LDA (Local Density Approximation). From the band structure for different values f pressure the pressure coefficient of the main gap is obtained and the pressure dependence of the refractive index is estimated.

Manufacture of gallium nitride thin film

Abstract: PURPOSE: To obtain a p-type GaN film without causing the film to deteriorate by irradiating an electron beam during the formation thereof with impurity doping. CONSTITUTION: Used is a gas source MBE system equipped with evaporating crucibles 2 and 3 and an electron-beam gun 4 in a vacuum container 1. Ga metal is placed in one crucible 2 and Mg metal is placed in the other 3; subsequently both are heated. NH 3 gas is fed; meanwhile, the shutter of the crucible 2 is opened to form a GaN thin films. Then the shutter of the crucible 3 is opened to perform doping; meanwhile, an electron beam is applied to proceed with deposition. This gives a gallium nitride p-n junction type laminated thin film with very little deterioration thereof. COPYRIGHT: (C)1993,JPO&Japio

Gallium nitride base compound semiconductor light-emitting device

Abstract: PURPOSE: To attain the increase in light-emitting intensity, the decline in driving voltage and the approach of light emitting wavelength to that of blue color in the light emitting diode of GaN base compound semiconductor. CONSTITUTION: Within the title gallium nitride base compound semiconductor having an n layer 4 comprising an n type gallium base nitride compound semiconductor (containing (Al x Ga 1-x N:X=0) and an i layer 5 comprising i type gallium nitride base compound semiconductor containing (Al x Ga 1-x N:X=0), the requirements of the i layer 250-1000Å thick, the light-emitting intensity of 50mcd, the driving voltage of 6.5-8.5V and the light emitting wavelength of 480-790nm can be fulfilled. COPYRIGHT: (C)1992,JPO&Japio

Defect formation processes and their influence on mechanical stresses in green glow gallium phosphide structures

Abstract: Defect formation and their influence on internal mechanical stresses in epitaxial gallium phosphide layers grown from a gallium melt with the addition of finely-dispersed gallium nitride particles in an atmosphere of hydrogen with ammonia are investigated in this paper. It is established that an increase from 0.04 to 0.1 vol. % in the ammonia content in the gas mixture will result in growth in the quantity of defects, in particular, inclusions of the second phase, as well as internal mechanical stresses, while for an NH3 content greater than 0.1 vol. % − in the formation of shallow cracks and stress relaxation. The dependence between the internal mechanical stresses, the volume fraction, and the dispersion of the GaN inclusions in gallium phosphide is shown. The results obtained are discussed within the framework of the proposed model.