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Four AlN nanowire-like structures were simultaneously grown directly without a buffer layer on four substrates-sapphire, quartz, Si(111), and 6H-SiC-via a mixed-source hydride vapor phase epitaxy (HVPE) method using a mixed source (Al+Ga) containing a small quantity of Ga at 1150 °C for 2 h. Deposition was carried out using a simplified reactor designed in series without any separation between the source and the growth zones. AlN nanostructures with hexagonal crystal structures were grown successfully and directly on thin, pre-grown AlN nucleation areas on the quartz substrates. Furthermore, AlN nanostructures were grown on the sapphire substrate without a buffer layer and on pre-grown epilayers on the Si (111) and the 6H-SiC substrates, respectively. The characteristics of the AlN nanowire-like structures grown on the four substrates were investigated using energy-dispersive X-ray spectrometry and field-emission scanning electron microscopy.

AIN epilayers of different thicknesses were grown directly on sapphire substrates without a buffer layer by using a mixed (Al+Ga) source containing 95 at% Al and a mixed-source hydride vapor phase epitaxy (HVPE) method at a temperature of around 1120°C. The grown epilayers consisted of an AlN alloy in the upper region and an AlGaN alloy in the nucleation region just above the sapphire substrate. The upper part of the epilayer gradually transformed from AlGaN into AlN owing to a decrease in the Ga content of the AlGaN alloy grown on the sapphire substrate with increasing growth thickness. The role of Ga in the mixed (Al+Ga) source in the growth of the epilayer directly on the sapphire substrate and the dependence of the growth mechanism of the epilayer with varying Ga contents on the growth thickness were investigated. We found that Ga in the mixed (Al+Ga) source only acted as an activation material that generated gaseous precursors rather than directly contributing to the growth of the epilayers. The mixed-source HVPE method appears suitable for the growth of thick AIN epilayers.

An electrode-evaporation technology on both the top and bottom sides of the bare vertical-type single chip separated from the traditional substrate by cooling, was developed for III-nitride vertical-type single chip LEDs with thick GaN epilayer. The post-process of the cooling step was followed by sorting the bare vertical-type single chip LEDs into the holes in a pocket-type shadow mask for deposition of the electrodes at the top and bottom sides of bare vertical-type single chip LEDs without the traditional substrate for electrode evaporation technology for vertical-type single chip LEDs. The variation in size of the hole between the designed shadow mask and the deposited electrodes owing to the use of the designed pocket-type shadow mask is investigated. Furthermore, the electrical and the optical properties of bare vertical-type single chip LEDs deposited with two different shapes of n-type electrodes using the pocket-type shadow mask are investigated to explore the possibility of the e-beam evaporation method.

An inorganic-organic hybrid junction has been fabricated by spin coating the p-type poly(3- hexylthiophene-2,5-diyl)(P3HT) and poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT: PSS) on an n-type GaN layer. The GaN layer was formed on Al2O3 by metal organic chemical vapor deposition(MOCVD) method. To investigate the effects of P3HT concentration on the electrical properties, we changed P3HT solution concentration and speed of spin coater. The currentvoltage (I-V ) characteristic of Au/PEDOT:PSS/P3HT/n-GaN shows rectifying behavior. The I-V characteristic was examined in the frame work of the thermionic emission model. The most proper rectifying behavior was obtained for 0.6 wt% and thickness below 65 nm of P3HT used diode. We expect that such hybrid structures, suitably developed, might be enable the fabrication of highquality electronic and optoelectronic devices.

We report on crystallographic analyses of one-dimensional GaN nanoneedles grown on a n-GaN epilayer by using hydride vapor phase epitaxy. The nanoneedles were grown with a HCl:NH3 gas flow ratio of 1:38 at 600 °C. The growth time of the GaN nanoneedles affected their morphologies. As time progressed, GaN dots nucleated and then evolved as nanoneedles. The vertical growth rate of GaN nanoneedles was higher than the lateral growth rate under optimized growth conditions. X-ray pole figure measurements were carried out using a four-axis diffractometer. For the sample grown for 20 min, we obtained discrete patterns with six strong dots and weak dough-nut and cotton swab patterns, indicating that most of the nanoneedles were grown ideally, but partially, in the x-y plane with an azimuthal rotation angle ϕ = 15 ~ 45° rotated to the substrate, and a few GaN nanoneedles were tilted by ±4° or by more than 32° from the vertical c-axis.

A carbon microsphere of a core-shell type was grown by using a new method of mixed-source hydride vapor phase epitaxy (HVPE). The surface and the cross section of the carbon microsphere grown by using the new method were observed by using scanning electron microscopy (SEM). The characteristics of the carbon microsphere were investigated by using X-ray photoelectron spectroscopy (XPS) and high-resolution transmission electron microscopy (HR-TEM). From these measurements, the diameters of the carbon spheres were about a few hundred micrometers. Furthermore, we showed that carbon microspheres of the core-shell type could be grown successfully by using a mixed-source HVPE method and that they had larger sizes than those grown by using existing methods. This mixed-source HVPE method is proposed as a new method for making carbon microspheres.

A thick AlN epilayer is grown directly on a c-plane sapphire substrate by using the hydride vapor phase epitaxy (HVPE) method with a small quantity of Al. The new type (RF + hot-wall) flow HVPE reactor used in the AlN epilayer growth is custommade. The growth temperatures of the source and the growth zones are set at 950 °C and 1145 °C, respectively. The characteristics of the AlN layer grown on a sapphire substrate are investigated by using energy dispersive spectroscopy (EDS), X-ray diffraction (XRD) and Fourier-transform infrared (FTIR) spectroscopy. The value of the full width at half maximum (FWHM) for the (002) peak from the AlN layer on the sapphire substrate is observed at 790 arcsec. From the small value of the FWHM, the AlN layer seems to be a well-arranged plane with a uniform (002) growth direction on a sapphire substrate.

The AlGaN layer has direct wide bandgaps ranging from 3.4 to 6.2 eV. Nowadays, it is becoming more important to fabricate optical devices in an UV region for the many applications. The high quality AlGaN layer is necessary to establish the UV optical devices. However, the growth of AlGaN layer on GaN layer is difficult due to the lattice mismatch and difference thermal expansion coefficient between GaN layer and AlGaN layer. In this paper, we attempted to grow the LED structure on GaN template by mixed-source HVPE method with multi-sliding boat system. We tried to find the optical and lattice transition of active layer by control the Al content in mixed-source. For the growth of epi layer, the HCl and gas were flowed over the mixed-source and the carrier gas was . The temperature of source zone and growth zone was stabled at 900 and , respectively. After the growth, we performed the x-ray diffraction (XRD) and electro luminescence (EL) measurement.

(Received October 12, 2011)(Revised October 24, 2011)(Accepted November 11, 2011)Abstract In general, the fabrications of the LEDs with mesa structure are performed grown by MOCVD method. In orderto etch and separate each chips, the LEDs are passed the RIE and scribing processes. The RIE process using plasma dryetching occur some problems such as defects, dislocations and the formation of dangling bond in surface result in declineof device characteristic. The SAG method has attracted considerable interest for the growth of high quality GaN epi layeron the sapphire substrate. In this paper, the SAG method was introduced for simplification and fabrication of the highquality epi layer. And we report that the size of selective area do not affect the characteristics of original LED. Thediameter of SAG circle patterns were choose as 2500, 1000, 350, and 200µm. The SAG-LEDs were measured to obtainthe device characteristics using by SEM, EL and I-V. The main emission peaks of 2500, 1000, 350, and 200µm were 485,480, 450, and 445 nm respectively. The chips of 350, 200µm diameter were observed non-uniform surface and resistancewas higher than original LED, however, the chips of 2500, 1000µm diameter had uniform surface and current-voltagecharacteristics were better than small sizes. Therefore, we suggest that the suitable diameter which do not affect thecharacteristic of original LED is more than 1000µm.Key wordsSelective area growth, InGaN/GaN, Multi quantum well, MOCVD, Band-filling effect, Screening effect

We report on the growth and characterization of nano and micro scale GaN structures selectively grown on the vertex of hexagonal GaN pyramids. near the vertex of hexagonal GaN pyramids was removed by optimized photolithgraphy process and followed by a selective growth of nano and micro scale GaN structures by metal organic vapor phase epitaxy (MOVPE). The pyramidal GaN nano and micro structures which have crystal facets of semi-polar {1-101} facets were formed only on the vertex of GaN pyramids and the size of the selectively grown nano and micro GaN structures was easily controlled by growth time. As a result of TEM measurement, Reduction of threading dislocation density was conformed by transmission electron microscopy (TEM) in the selectively grown nano and micro GaN structures. However, stacking faults were newly developed near the edge of film because of the roughness and nonuniformity in thickness of the film.

The Cu is the absorber material for thin film solar cell with high absorption coefficient of . In the case of CIGS, the movable energy band gap from (1.00 eV) to (1.68 eV) can be acquired while controlling Ga contain ratio. Generally, the co-evaporator method have used for development and fabrication of the CIGS absorption layer. However, this method should need many steps and lengthy deposition time with high temperature. For these reasons, in this paper, a new growth method of CIGS layer was attempted to hydride vapor transport (HVT) method. The CIGS mixed-source material reacted for HCl gas in the source zone was deposited on the substrate after transporting to growth zone. c-plane and undoped GaN were used as substrates for growth. The characteristics of grown samples were measured from SEM and EDS.

We report on the growth and characteristics of the structural and optical properties of InGaN nano-structures doped with antimony (Sb) as a catalyst. The use of catalyst has been explored to modify the growth and defect generation during strained layer heteroepitaxial growth. We performed the growth of the InGaN nano-structures on c-sapphire substrates using mixed-source hydride vapor phase epitaxy (HVPE). The characteristic of samples was measured by scanning electron microscope (SEM) and photoluminescence (PL). The aligning direction of c-axis of the InGaN nano-structures was changed from vertical to parallel or inclined to the surface of substrates when the Sb was added as a catalyst. The indium composition was estimated about 3.2% in both cases of with or without the addition of Sb in the InxGal-xN structures. From the results of InGaN nano-structures formed with the addition of Sb, we can expect the performance of optical devices would be more improved by reduced piezo-electric field if we use the InGaN nano-structures of which c-axes are aligned parallel to the substrates as an active layer.

CuInGaSe(CIGS) mixed-source was prepared by hydride vapor phase epitaxy (HVPE). Each metal was mixed in regular ratio and soaked at for 90 minutes in nitrogen atmosphere. After making the mixed-source to powder state, the pellet was made by the powder. The diameter of pellet is 10 mm. The CIGS thin film was deposited on soda lime glass evaporated Mo layer bye-beam evaporator. To confirm the crystallization, we measured X-ray diffraction (XRD). High intensity X-ray peaks diffracted from (112), (204)/(220), (116)/(312) and (400) of CIGS thin film and from (110) of Mo were confirmed by XRD measurement.

In this paper, we report structural changes in InGaN micro-structures grown by using mixed-source hydride vapor phase epitaxy (HVPE). Hexagonal nanorods, bunched with many submicron-sized legs and tetrapod-shaped InGaN micro-structures, are grown on r-plane sapphire, c-plane sapphire and Si (111) substrates. As the growth temperature is increased, the overall shape of the InGaN structures changes from clusters of some needle-like legs to bunch shapes of many legs with thicker and hexagonal edges. The grown InGaN structures were analyzed by using X-ray photoelectron spectroscopy (XPS) to characterize the InGaN ternary crystal alloy. The indium mole fractions of the InGaN structures grown at 650 C, 700 C and 750 C were 44 %, 37 % and 27 %, respectively.

The selective area growth (SAG) of AlGaN/InGaN/AlGaN light-emitting diodes (LEDs) is performed by mixed-source hydride vapor phase epitaxy (HVPE). The structure is grown on a n-GaN templated (0001) sapphire substrate. The SAG-double heterostructure (DH) is consisted of a Te-doped AlGaN cladding layer, an InGaN active layer, a Mg-doped AlGaN cladding layer, and a Mg-doped GaN capping layer. All of the epitaxial layers of LED structure are grown consecutively with a multi-sliding boat system. Room-temperature electroluminescence (EL) characteristics show an emission peak wavelength of 400 nm with a full width at half-maximum (FWHM) of approximately 0.38 eV (at 20 mA). We find that the mixed-source HVPE method with multi-sliding boat system is possible to be one of the growth methods of III-nitride LEDs. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

The selective area growth (SAG) of AlGaN/InGaN/AlGaN light-emitting diodes (LEDs) is performed by mixed-source hydride vapor phase epitaxy (HVPE). In order to obtain the SAG-AlGaN/InGaN/AlGaN heterostructure, a special graphite fixture to use in HVPE is designed. First, an n-type AlGaN layer is grown at 1090 °C on a GaN templated (0001) sapphire substrate with a patterned SAG-structure of a silicon oxide (SiO2). On this selectively grown n-type AlGaN layer, a nominally undoped-InGaN layer is grown using an In-Ga mixed metallic source at 990 °C. After the growth of InGaN layer, Mg-doped AlGaN and Mg-doped GaN layers are grown as a cladding and capping layers at 1090 °C and 1050 °C, respectively. All of the epitaxial layers of LED structure are grown consecutively with a multi-sliding boat system. Room-temperature electroluminescence (EL) characteristics show an emission peak wavelength of 415 nm with a full width at half-maximum (FWHM) of approximately 0.37 eV. We find that the mixed-source HVPE method with multi-sliding boat system is possible to be one of the growth methods of III-nitride LEDs. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

The InGaN layers on GaN templated sapphire (0001) and Si (111) substrates are grown by mixed-source hydride vapor phase epitaxy (HVPE) method. As a new attempt in obtaining an InGaN layers, the growth of the thick InGaN layer is performed by putting small amount of Ga into the In source. The InGaN layer is compounded from chemical reaction between a NH3 and an Indium-gallium chloride formed by HCl flown over metallic In mixed with Ga. The InGaN layer is analyzed by X-ray photoelectron spectroscopy (XPS) to characterize the InGaN ternary crystal alloy. The optical property of the selective area growth (SAG) of the InGaN layer is investigated by the photoluminescence (PL) spectrum and the cathodoluminescence (CL) images. Indium compositions are estimated to be in the range 3-10%. In order to obtain the GaN layer on GaN templated Si (111) substrates, an InGaN layer is used as an intermediate layer. The PL and CL of the InGaN intermediate layer are measured at 300K. We find that the InGaN intermediate layer is possible to be one of the growth methods of thick GaN layer on Si substrates by HVPE method. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

The AlxGa1–xN, Te-doped GaN and Mg-doped GaN layers on GaN/Al2O3 substrates are grown by mixed-source hydride vapor phase epitaxy (HVPE) method. The metallic Ga mixed with Al is used as group III source material to get the AlxGa1–xN layers. The values of the compositions x of the AlxGa1–xN layers characterized by X-ray diffraction (XRD) measurements are 0.6% ∼ 80% at the various temperatures of the source zone. The metallic Ga mixed with Te (or Mg) is used as source material for n-type (or p-type) doping. The electron concentrations of the Te-doped GaN layers are varied from 1.8 × 1017 to 8.3 × 1018/cm3. The hole concentrations of the Mg-doped GaN layers are varied from 1.5 × 1016 to 3.2 × 1016/cm3. We find that the mixed-source HVPE method is suitable to get a thick AlGaN layer with an arbitrary composition, a Te-doped GaN layer with a high n-type concentration and a Mg-doped GaN layer with p-type concentration. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

We prepared InGaN light-emitting diodes (LEDs) with the active layers grown from a mixed source of Ga–In–N materials on an n-type GaN substrate by a selective-area growth method and three fabrication steps: photolithography, epitaxial layer growth, and metallization. The preparation followed a previously developed experimental process using apparatus for mixed-source hydride vapor-phase epitaxy (HVPE), which consisted of a multi-graphite boat, for insulating against the high temperature and to control the growth rate of epilayers, filled with the mixed source on the inside and a radio-frequency (RF) heating coil for heating to a high temperature (T > 900 °C) and for easy control of temperature outside the source zone. Two types of LEDs were prepared, with In compositions of 11.0 and 6.0% in the InGaN active layer, and room-temperature electroluminescence measurements exhibited a main peak corresponding to the In composition at either 420 or 390 nm. The consecutive growth of InGaN LEDs by the mixed-source HVPE method provides a technique for the production of LEDs with a wide range of In compositions in the active layer.

High Al-composition AlGaN and AlN epilayers were grown directly on Si(111) substrate by a hydride vapor phase epitaxy (HVPE) method with a melted mixed source in a graphite boat set in a source zone with high temperatures of T = 700 and 800 °C, respectively. The presence of the Ga material in the mixed source of Ga and Al promoted the growth of AlN and AlGaN epilayers in the growth zone. When the temperature in the source zone was 800 °C, the crystalline quality of the AlN and AlGaN epilayers increased as the ratio of Ga to Al increased, and the optimum mix ratio of Ga to Al for the growth of AlN epilayers was approximately 0.35–0.42, obtained from a numerical fitting analysis of the X-ray diffraction (XRD) data for these epilayers. It appears that they can be grown directly by our melted-mixed-source HVPE method in a high-temperature source zone.

We developed a vertical-type light-emitting diode (LED) in which the substrate is removed using a hydride vapor phase epitaxy (HVPE) apparatus consisting of a multi-graphite boat filled with a mixed source and a high-temperature (T ≈ 900 °C) RF heating coil outside the source zone. The new chip-growth process with a significant reduction in the number of production steps is completed in only four steps, namely, photolithography, epitaxial layer growth, sorting, and metallization. We analyze the emission mechanism of these lights from measurement results to validate the characteristics of the light emitted from these vertical-type blue LEDs and white LEDs (WLEDs) without substrates, and propose that this mixed-source HVPE method may be a promising production technique for LEDs.

Even though a patterned sapphire substrate (PSS) has been used for the growth of a high-quality epilayer because of its many advantages, it has not been successfully used to grow an AlN epilayer for ultraviolet (UV) light-emitting diodes (LEDs) on a PSS up to now. We report the growth of a high-quality AlN epilayer on a PSS, as a substrate for the manufacture of UV LEDs, by hydride vapor phase epitaxy (HVPE). The X-ray diffraction (XRD) peaks for the AlN epilayer grown on the PSS indicate that crystalline AlN with a wurtzite structure was grown successfully on the PSS. Furthermore, HVPE combining both in situ HVPE technology and liquid-phase epitaxy (LPE) using a mixed source is proposed as a novel method for the growth of a flat AlN epilayer on a PSS.

In this paper, we approached a novel fabrication for non phosphor white light emitting diodes (LEDs) by the growth of AlGaN/InAlGaN double-hetero structures using by mixed-source hydride vapor phase epitaxy (HVPE) system with multi-sliding boat. It is unique crystal growth technology different from conventional HVPE and metal organic chemical vapor deposition (MOCVD) system using mixed metal source of aluminum, indium and gallium. The characterization of non phosphor white LEDs was examined by photoluminescence (PL) and electroluminescence (EL). The results of EL were found green and yellow emissions as spectrum peaks near 500, 550, and 610 nm definitely. The CIE chromaticity coordinates of white LEDs was measured at injection current 30 mA. Our results are nearly positions; at x = 0.28 and y = 0.31. Even though the LED needs more improved in optical properties, we demonstrated achieving phosphor-free solid-state white lighting.

In this paper, the selective area growth (SAG) of SAG-UV light-emitting diode (LED) was performed by mixed-source hydride vapor phase epitaxy (HVPE) with a multi-sliding boat system. The SAG-UV LED consists of a Si-doped GaN layer, an Si-doped AlGaN cladding layer, an AlGaN active layer, an Zn-doped AlGaN cladding layer, and a Zn-doped GaN capping layer. All of the epitaxial layers of LED structure were grown consecutively with a multi-sliding boat system. Room-temperature electroluminescence (EL) characteristics show an emission peak wavelength of 330 nm at room temperature. The aging test result of SAG-UV LED shows that the current was changed from 27.7 to 31.2 mA during 170 h at room temperature. At the current–voltage (I–V) measurement, the turn-on voltage of the SAG-UV LED is 3.5 V at room temperature. The value of the series resistance is about 200 Ω. We find that the mixed-source HVPE method with multi-sliding boat system is possible to be one of the growth methods of ultra-violet LEDs with high quality epi-layer.

We studied the crystallographic orientation of GaN nanostructures grown on Si(111) and Al2O3 substrates. We evaluated Zr metal as a novel alternative to conventional buffer layers such as AlN and ZnO. One-dimensional structures (nanorods and nanoneedles) were grown by hydride vapor phase epitaxy at 650 and 600 °C, and investigated using field-emission scanning electron microscopy (FE-SEM) and X-ray diffraction (XRD) analysis. FE-SEM images showed that the GaN nanorods had a uniform diameter along the growth direction. XRD results indicated that the nanostructures had a hexagonal crystal structure, and pole figure measurements revealed that GaN nanostructures grown on the Si(111) substrate had a stronger c-axis crystallographic orientation than those grown on the Al2O3 substrate.

We report the characterization of the InGaN/GaN multi-quantum-well (MQW) light-emitting diode (LED) grown on a patterned sapphire substrate by metal organic chemical vapor deposition (MOCVD) using the selective area growth (SAG) method. The SAG patterns were designed to be circular and their diameters were 700 and 200 µm. After the growth, the InGaN/GaN MQW LED of 200 µm diameter had various crystal facets and a shape similar to volcanic craters, which were not observed in the 700-µm-diameter sample. We obtained an active layer with compositional nonuniformity and superior optical properties. We found wide electroluminescence (EL) spectral peaks near 470, 570, and 600 nm. The distribution of the EL spectrum of the sample was similar to that of a conventional phosphor-converted white LED.

CuInGaSe (CIGS) mixed-source was prepared by hydride vapor transport method (HVT). The new source synthesis method was attempted by mixing several metals such as Cu, In, Ga, and Se with 3:5:1:4 mass ratios. This mixed-source was soaked at 1090 °C for 90 min in nitrogen atmosphere. Then, the CIGS was grinded up and formed the state of powder and the CIGS pellet was made by pressure machine. The diameter of pellet is 10 mm. The CIGS thin film was deposited on soda lime glass with evaporated molybdenum layer by e-beam evaporating this CIGS pellet. For crystallization of CIGS thin film, we measured scanning electron microscope (SEM), energy dispersive spectroscopy (EDS), and X-ray diffraction (XRD). High intensity X-ray peaks diffracted from (112), (204)/(220), (116)/(312), and (400) of CIGS thin film and from (110) of Mo were confirmed by XRD measurement.

GaN/InGaN heterostructure on r-plane Al2O3 substrate is grown by mixed-source hydride vapor phase epitaxy (HVPE). The InGaN/GaN heterostructure is grown by a selective-area growth (SAG) method. The heterostructure consists of an undoped GaN layer, an InGaN layer, and a Mg-GaN layer. NH3 and gallium (or indium) chloride formed with HCl, which is owed over for a mixed source, are used as gallium (or indium) and nitrogen sources. The gas ow rates of HCl and NH3 are maintained at 10 sccm and 500 sccm, respectively. The temperature of the GaN source zone is 650 C. In the case of the InGaN, the temperature of the source zone is 900 C. The growth temperatures of the GaN and InGaN layers are 820 C and 850 C, respectively. The electroluminescence (EL) peak of the GaN/InGaN heterostructure is 468 nm and the full width at half maximum (FWHM) is 89.7 nm. These results demonstrate that the heterostructure of III-nitrides on r-plane sapphire can be successfully grown by mixed-source HVPE.