• Journal of the Korean Crystal Growth and Crystal Technology
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• v.29 no.3
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• pp.83-90
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• 2019

In this paper, Mg-doped AlN epilayers for power semiconductor devices are grown by mixed-source hydride vapor phase epitaxy. Magnesium is used as p-type dopant material in the grown AlN epilayer. The AlN epilayers on the GaN-templated sapphire substrate and GaN-templated-patterned sapphire substrate (PSS), respectively, as the base substrates for device application, were selectively grown. The surface and the crystal structures of the AlN epilayers were investigated by field emission scanning electron microscopy (FE-SEM) and high-resolution-X-ray diffraction (HR-XRD). From the X-ray photoelectron spectroscopy (XPS) and Raman spectra results, the p-type AlN epilayers grown by using the mixed-source HVPE method could be applied to power devices.

• Korean Journal of Materials Research
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• v.8 no.7
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• pp.591-595
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• 1998

In this work, the freestanding GaN single crystalline substrates without cracks were grown by hydride vapor phase epitaxy (HVPE) and its some properties were investigated. The GaN substrate, having a current maximum size of 350 $\mu\textrm{m}$-thickness and 100$\textrm{mm}^2$ area, were obtained by HVPE growth of thick film GaN on sapphire substrate and subsequent mechanical removal of the sapphire substrate. A lattice constant of $C_o$= 5.18486 $\AA$ and a FWHM of DCXRD was 650 arcsec for the single crystalline GaN substrate. The low temperature PL spectrum consist of three excitonic emission and a deep D- A pair recombination at 1.8eV. The Raman E, (high) mode frequency was 567$cm^{-1}$ which was the same as that of strain free bulk single crystals. The Hall mobility and carrier concentration was 283$cm^3$<\ulcornerTEX>/ V.sand 1.1$\times$$10^{18}cm^{-3}$, respectively.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.11a
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• pp.425-425
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• 2008

Bismuth-antimony-telluride based thermoelectric thin film materials were prepared by metal organic vapor phase deposition using trimethylbismuth, triethylantimony and diisopropyltelluride as metal organic sources. A planar type thermoelectric device has been fabricated using p-type $Bi_{0.4}Sb_{1.6}Te_3$ and n-type $Bi_2Te_3$ thin films. Firstly, the p-type thermoelectric element was patterned after growth of $4{\mu}m$ thickness of $Bi_{0.4}Sb_{1.6}Te_3$ layer. Again n-type $Bi_2Te_3$ film was grown onto the patterned p-type thermoelectric film and n-type strips are formed by using selective chemical etchant for $Bi_2Te_3$. The top electrical connector was formed by thermally deposited metal film. The generator consists of 20 pairs of p- and n-type legs. We demonstrate complex structures of different conduction types of thermoelectric element on same substrate by two separate runs of MOCVD with etch-stop layer and selective etchant for n-type thermoelectric material. Device performance was evaluated on a number of thermoelectric devices. To demonstrate power generation, one side of the device was heated by heating block and the voltage output was measured. The highest estimated power of 1.3mW is obtained at the temperature difference of 45K. We provide a promising approach for fabricating thin film thermoelectric generators by using MOCVD grown thermoelectric materials which can employ nanostructures for high thermoelectric properties.

• Journal of IKEEE
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• v.22 no.2
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• pp.427-431
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• 2018

This research was worked about $Ga_2O_3$ Epi wafer that was one of the mose wide band gap semiconductors to be used power semiconductor industry. This wafer was grown $5.3{\mu}m$ thickness on Sn doped $Ga_2O_3$ Substrate by HVPE(Hydride Vapor Phase Epitaxy). Generally, we can fabricate 600V class power semiconductor devices when the thickness of compoound power semiconductor is $5{\mu}m$. but in case of $Ga_2O_3$ Epi wafer, we can obtain over 1000V class. As a result of J-V measurment of the grown $Ga_2O_3$ Epi wafer, we obtain $2.9-7.7m{\Omega}{\cdot}cm^2$ on resistance. Specially, in case of reverse, we comfirmed a little leakage current when the reverse voltage is over 200V.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.40 no.9
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• pp.666-672
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• 2003

In this paper, we described the fabrication and the performance of wavelength tunable distributed bragg reflector (DBR) laser diode (LD), having different waveguide coupling mechanisms; integrated-twin-guide (ITG) DBR-LD and butt coupled (BT) DBR-LD. This deviceis fabricated by metal organic vapor phase epitaxy (MOVPE) growth and planar buried heterostructure (PBH)-type transverse current confinement structure. The result of measurement, the optical performance of BT-DBR-LD is better over 2 times than that of ITG-DBR-LD at the variation of threshold current and output power, and slop efficiency due to the higher coupling efficiency of the butt coupled structure than the integrated twin guide structure. The maximum wavelength tuning range is about 7.2nm for ITG DBR-LD and 7.4nm for BT DBR-LD. Both types of lasers have a very high yield of single mode operation with a side-mode suppression ratio of more than 35dB.

• Journal of Sensor Science and Technology
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• v.12 no.6
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• pp.282-288
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• 2003

We report the growth of HgCdTe by metal organic vapor phase epitaxy (MOVPE), using (211)B CdTe/Si substrates grown by molecular beam epitaxy (MBE). The surface morphology of these films is very smooth with hillock free. The etch pit densities (EPD) and full widths at half maximum (FWHM) of x-ray rocking curves exhibited that the crystalline quality of HgCdTe epilayer on MBE grown CdTe/Si was improved compare to HgCdTe on GaAs substrate. The Hall parameters of undoped HgCdTe layers on CdTe/Si showed n-type behavior with carrier concentration of $8{\times}10^{14}/cm^3$ at 77K. But HgCdTe on GaAs showed p-type conductivity due to in corporation of p-type impurities during GaAs substrate preparation. It is thought that these results are applicable for large area HgCdTe forcal plane arrays of $1024{\times}1024$ format and beyound.

• Korean Journal of Materials Research
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• v.23 no.12
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• pp.732-736
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• 2013

AlN epilayers were grown on a c-plane sapphire substrate using hydride vapor phase epitaxy (HVPE). A series of AlN epilayers were grown at $1120^{\circ}C$ with V/III ratios 1.5, 2.5 and 3.5, and the influence of V/III ratio on their properties was investigated. As the V/III ratio was increased, the surface roughness (RMS roughness), Raman shift of $E_2$ high peaks and full-width at half-maximum (FWHM) of symmetrical (002) & asymmetrical (102) of the AlN epilayers increased. However, the intensities of the Raman $E_2$ high peaks were reduced. This indicates that the crystal quality of the grown AlN epilayers was degraded by activation of the parasitic reaction as the V/III ratio was increased. Smooth surface, stress free and high crystal quality AlN epilayers were obtained at the V/III ratio of 1.5. The crystal quality of AlNepilayers is worsened by the promotion of three-dimensional (3D) growth mode when the flow of $NH_3$ is high.

• Applied Chemistry for Engineering
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• v.10 no.2
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• pp.225-230
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• 1999

Low pressure metal organic chemical vapor deposition (LPMOCVD) of $Li_2O$ solid thin films from Li(DPM) in nitrogen-oxygen or argon-oxygen atmosphere was experimentally investigated by using a small hot wall tubular type reactor. XRD and ESCA analysis revealed that $Li_2CO_3$ film grew in nitrogen-oxygen atmosphere and $Li_2O$ grew in argon-oxygen atmosphere. The grown lithium oxide or carbonate reacted with silicon or silica base materials to produce silicates. The CVD model analysis by means of the well-known micro trench method and Monte Carlo simulation was not fully successful, but a set of data on gas phase reaction rate constant and surface reaction constant was obtained.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.22 no.5
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• pp.443-447
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• 2009

Bismuth-antimony-telluride based thermoelectric thin film materials were prepared by metal organic vapor phase deposition using trimethylbismuth, triethylantimony and diisopropyltelluride as metal organic sources. A planar type thermoelectric device has been fabricated using p-type $Bi_{0.4}Sb_{1.6}Te_3$ and n-type $Bi_{2}Te_{3}$ thin films. Firstly, the p-type thermoelectric element was patterned after growth of $5{\mu}m$ thickness of $Bi_{0.4}Sb_{1.6}Te_3$ layer. Again n-type $Bi_{2}Te_{3}$ film was grown onto the patterned p-type thermoelectric film and n-type strips are formed by using selective chemical etchant for $Bi_{2}Te_{3}$. The top electrical connector was formed by thermally deposited metal film. The generator consists of 20 pairs of p- and n-type legs. We demonstrate complex structures of different conduction types of thermoelectric element on same substrate by two separate runs of MOCVD with etch-stop layer and selective etchant for n-type thermoelectric material. Device performance was evaluated on a number of thermoelectric devices. To demonstrate power generation, one side of the device was heated by heating block and the voltage output was measured. The highest estimated power of 1.3 ${\mu}m$ is obtained at the temperature difference of 45 K.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.35 no.10
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• pp.1089-1095
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• 2011

Numerical simulation is performed for nucleate boiling on a micro-finned surface, which has been widely used to enhance heat transfer, by solving the equations governing the conservation of mass, momentum, and energy in the liquid and vapor phases. The bubble motion is determined by a sharp-interface level-set method, which is modified to include the effect of phase change and to treat the no-slip and contact-angle conditions, as well as the evaporative heat flux from the liquid microlayer on immersed solid surfaces such as micro fins and cavities. The numerical results for bubble formation, growth, and departure on a microstructured surface including fins and cavities show that the bubble behavior during nucleate boiling is significantly influenced by the fin-cavity arrangement and the fin-fin spacing.