• Journal of the Korean Crystal Growth and Crystal Technology
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• v.34 no.1
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• pp.36-39
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• 2024

As interest in power semiconductors is growing recently, research on device design and application using light energy gap materials such as SiC and GaN is being actively conducted. Because AlN single crystals have a larger energy gap than the above mentioned materials, research on high-power devices is also in progress, but commercialized wafers have not yet been reported, so research is needed. In this study, we applied the HVPE (Hydride vapor phase epitaxy) method to produce AlN single crystals and attempted to obtain bulk single crystals using our own manufacturing equipment. To this end, we would like to report the results of securing the growth conditions for single crystals. we would like to report on the change in the shape of the grown crystal according to the change in temperature.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.19 no.1
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• pp.6-10
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• 2009

In this paper, a selective area growth (SAG) of a GaN/AlGaN double heterostructure (DH) has been performed on r-plane sapphire substrate by using the mixed-source hydride vapor phase epitaxy (HVPE) with multi-sliding boat system. The SAG-GaN/AlGaN DH consists of GaN buffer layer, Te-doped AlGaN n-cladding layer, GaN active layer, Mg-doped AlGaN p-cladding layer, and Mg-doped GaN p-capping layer. The electroluminescence (EL) characteristics show an emission peak of wavelength, 439 nm with a full width at half maximum (FWHM) of approximately 0.64 eV at 20 mA. The I-V measurements show that the turn-on voltage of the SAG-GaN/AlGaN DH is 3.4 V at room temperature. We found that the mixed-source HVPE method with a multi-sliding boat system was one of promising growth methods for III-Nitride LEDs.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.9 no.2
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• pp.168-172
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• 1999

The 9 $\mu\textrm{m}$ GaN films on sapphire substrate were grown by Hydride vapor phase epitaxy. Dislocation density of these GaN films was measured by TEM. GaN film with crack free and mirror surface was directly grown on sapphire substrate. The dislocation density of this GaN film was $2{\times}10^9/cm^2$. The surface of GaN film on patterned GaN layer also presented a smooth mirror. But a part of GaN surface included holes because of incomplete coalescence. The dislocation density of GaN film above the mask region was lower than that in the window region. Especially, the dislocation density in the region between mask center and window region was close to dislocation free. The average dislocation density of ELO GaN was $8{\times}10^7/cm^2$.

• Journal of the Korean Vacuum Society
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• v.18 no.1
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• pp.44-48
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• 2009

The effect of temperature gradient between the substrate and ambient gas on the structural characteristics of GaN nanorods grown on r-plane sapphire substrates by hydride vapor phase epitaxy was investigated. The density, diameter, and length strongly depended on the tempearture gradient. In addition, the cross-sectional shape of the nanorrods at the end of growth was found to be more dependedent on the temperature of a substrate itself than the temperature gradient.

• Korean Journal of Materials Research
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• v.7 no.6
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• pp.492-497
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• 1997

HVPE를 이용하여 sapphire기판 위에서 후막 GaN의 성장특성을 조사하였다. 성장온도가 100$0^{\circ}C$에서 110$0^{\circ}C$로 증가하여도 성장속도는 영향을 받지않고 50-60$\mu\textrm{m}$/hr의 성장속도를 나타내었으나 표면특성과 결정성은 향상되었다. 110$0^{\circ}C$에서 성장된 후막 GaN는 DCXRD측정결과 451arcsec의 반티폭을 나타내었으며, PL측정결과 10K에서 19meV의 반치폭을 나타내었다. Ga 공급원의 온도가 93$0^{\circ}C$에서 77$0^{\circ}C$로 감소하여도 성장속도는 영향을 받지 않았으나, 77$0^{\circ}C$의 온도에서 GaN의 결정성이 향상되었다. HCI의 양이 5sccm에서 20sccm으로 증가함에 따라 성장속도가 15$\mu\textrm{m}$/hr에서 60$\mu\textrm{m}$/hr으로 증가하였으며, 표면특성도 향상되었다.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.16 no.4
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• pp.157-161
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• 2006

InGaN layers on GaN templated sapphire (0001) substrates were grown by mixed-source hydride vapor phase epitaxy (HVPE) method. In order to get InGaN layers, Ga-mixed In metal and $NH_3$ gas were used as group III and group V source materials, respectively. The InGaN material was compounded from chemical reaction between $NH_3$ and indium-gallium chloride farmed by HCl flowed over metallic In mixed with Ga. The grown layers were confirmed to be InGaN ternary crystal alloys by X-ray photoelectron spectroscopy (XPS). In concentration of the InGaN layers grown by selective area growth (SAG) method was investigated by the photoluminescence (PL) and cathodoluminescence (CL) measurements. Indium concentration was estimated to be in the range 3 %. Moreover, as a new attempt in obtaining InAlGaN layers, the growth of the thick InAlGaN layers was performed by putting small amount of Ga and Al into the In source. We found the new results that the metallic In mixed with Ga (and Al) as a group III source material could be used in the growth process of the In(Al)GaN layers by the mixed-source HVPE method.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.30 no.1
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• pp.1-6
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• 2020

In this research, 50 nm thick AlN thin films were deposited on the patterned sapphire (0001) substrate by using HVPE (Hydride Vapor Phase Epitaxy) system and then epitaxial layer structure was grown by MOCVD (metal organic chemical vapor deposition). The surface morphology of the AlN buffer layer film was observed by SEM (scanning electron microscopy) and AFM (atomic force microscope), and then the crystal structure of GaN films of the epitaxial layer structure was investigated by HR-XRC (high resolution X-ray rocking curve). The XRD peak intensity of GaN thin film of epitaxial layer structure deposited on AlN buffer layer film and sapphire substrate was rather higher in case of that on PSS than normal sapphire substrate. In AFM surface image, the epitaxial layer structure formed on AlN buffer layer showed rather low pit density and less defect density. In the optical output power, the epitaxial layer structure formed on AlN buffer layer showed very high intensity compared to that of the epitaxial layer structure without AlN thin film.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.29 no.6
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• pp.348-352
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• 2016

In this paper, GaN film was grown on AlN/PSS by hydride vapor phase epitaxy compared with GaN on planar sapphire. Thin AlN layer for buffer layer was deposited on patterned sapphire substrate (PSS) by metal organic chemical vapor deposition. Surface roughness of GaN/AlN on PSS was remarkably decreased from 28.31 to 5.53 nm. Transmittance of GaN/AlN grown on PSS was lower than that of planar sapphire at entire range. XRD spectra of GaN/AlN grown on PSS corresponded the wurzite structure and c-axis oriented. The full width at half maximum (FWHM) values of ${\omega}$-scan X-ray rocking curve (XRC) for GaN/AlN grown on PSS were 196 and 208 arcsec for symmetric (0 0 2) and asymmetric (1 0 2), respectively. FWHM of GaN on AlN/PSS was improved more than 50% because of lateral overgrowth and AlN buffer effect.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.19 no.4
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• pp.159-164
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• 2009

We fabricated 40 nm-thick cobalt silicide ($CoSi_2$) as a buffer layer, on p-type Si(100) and Si(111) substrates to investigate the possibility of GaN epitaxial growth on $CoSi_2$/Si substrates. We deposited GaN using a HVPE (hydride vapor phase epitaxy) with two processes of process I ($850^{\circ}C$-12 minutes + $1080^{\circ}C$-30 minutes) and process II ($557^{\circ}C$-5 minutes + $900^{\circ}C$-5 minutes) on $CoSi_2$/Si substrates. An optical microscopy, FE-SEM, AFM, and HR-XRD (high resolution X-ray diffractometer) were employed to determine the GaN epitaxy. In case of process I, it showed no GaN epitaxial growth. However, in process II, it showed that GaN epitaxial growth occurred. Especially, in process II, GaN layer showed selfaligned substrate separation from silicon substrate. Through XRD ${\omega}$-scan of GaN <0002> direction, we confirmed that the combination of cobalt silicide and Si(100) as a buffer and HVPE at low temperature (process II) was helpful for GaN epitaxy growth.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1996.05a
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• pp.72-75
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• 1996

A hydride vapor phase epitaxy (HVPE) method is performed to prepare the GaN thin films on c-plane sapphire substrate. The full-width at half maximum of double crystal X-ray rocking curves from 20$\mu\textrm{m}$-thick GaN was 576 arcsecond. The photoluminescence spectrum measured 10 K shows the hallow bound exciton (I$_2$) line and weak donor-acceptor peak, however, there was not observed deep donor-acceptor pair recombination indicate the GaN crystals prepared in this study are of high purity and high crystalline quality. The GaN layer is n-type conducting with electron mobility of 72 $\textrm{cm}^2$/V$.$sec and with carrier concentration of 6 x 10$\^$18/cm/sup-3/.