• Proceedings of the Materials Research Society of Korea Conference
• /
• 1995.11a
• /
• pp.14-14
• /
• 1995

• Proceedings of the Korean Vacuum Society Conference
• /
• 2012.02a
• /
• pp.415-415
• /
• 2012

ZnO nanostructures were synthesized by a vapor phase transport process in a single-zone furnace within a horizontal quartz tube with an inner diameter of 38 mm and a length of 485 mm. The ZnO nanostructures were grown on Au-catalyzed Si(100) substrates by using a mixture of zinc oxide and graphite powders. The growth of ZnO nanostructures was conducted at $800^{\circ}C$ for 30 min. High-purity Ar and $O_2$ gases were pushed through the quartz tube during the process at a flow rate of 100 and 10 sccm, respectively. The sequence of ON/OFF cycles of the Ar gas flow was repeated, while the $O_2$ flow is kept constant during the growth time. The Ar gas flow was ON for 1 min/cycle and that was OFF for 2 min/cycle. The structure and optical properties of the ZnO nanostructures were investigated by field-emission scanning electron microscope, X-ray diffraction, temperature-dependent photoluminescence. The preferred orientation of the ZnO nanostructures was along c-axis with hexagonal wurtzite structure.

• Journal of the Korean Crystal Growth and Crystal Technology
• /
• v.20 no.3
• /
• pp.125-132
• /
• 2010

For typical governing dimensionless parameters of Ar = 5, Pr = 1.16, Le = 0.14, Pe = 3.57, Cv = 1.02, $Gr_s=2.65{\times}10^6$, the effects of thermo physical properties such as a molecular weight, a binary diffusivity coefficient, a partial pressure of component B on solutally buoyancy-driven convection (solutal Grashof number $Gr_s=2.65{\times}10^6$) are theoretically investigated for further understanding and insight into an essence of solutal convection occurring in the vapor phase during the physical vapor transport of a $Hg_2Cl_2-N_2$ system. The solutally buoyancy-driven convection is significantly affected by any significant disparity in the molecular weight of the crystal components and the impurity gas of nitrogen. The solutal convection in a vertical orientation is found to be more suppressed than a tenth reduction of gravitational accelerations in a horizontal orientation. For crystal growth parameters under consideration, the greater uniformity in the growth rate is obtained for either solutal convection mode in a vertical orientation or thermal convection mode in horizontal geometry. The growth rate is also found to be first order exponentially decayed for $10{\leq}P_B{\leq}200$ Torr.

• Journal of the Korean Ceramic Society
• /
• v.33 no.3
• /
• pp.355-361
• /
• 1996

Yttria stabilized zirconia (YSZ) thin films were prepared by the electrochemical vapor deposition (EVD) method on the porous Al2O3 substrates. Y2O3 mol% of thin film was linearly increased with yttrium mole fraction of vapor phase. As yttrium mole fraction(Zyc13=0.18) increased dense and faceted thin films were enhanced. However as the yttrium mole fraction (Zyc13=0.04) decreased porous thin films with monoclinnic phase prevailed. With increasing pressure difference of substrate sides penetration depth decreased porosity and amount of monoclinic phase in the films increased.

• Journal of the Korean Crystal Growth and Crystal Technology
• /
• v.18 no.1
• /
• pp.10-14
• /
• 2008

We synthesized GaN nanowires with high quality using the vapor phase epitaxy technique. The GaN nanowires were obtained at a temperature of $950^{\circ}C$. The Ar and $NH_3$ flow rates were 1000 sccm and 50 sccm, respectively. The shape of the GaN nanowires was confirmed through FESEM analysis. We were able to conclude that the GaN nanowires synthesized via vapor-solid (VLS) mechanism when the source was closed to the substrate. On the other side, the VS mechanism changed to vapor-liquid-solid (VLS) as the source and the substrate became more distant. Therefore, we can suggest that the large amount of Ga source from initial growth interrupt the role of catalyst on the substrate.

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

• 전자공학회논문지 IE
• /
• v.48 no.2
• /
• pp.1-5
• /
• 2011

The epitaxial GaN layer of $120{\mu}m$ ~ $300{\mu}m$ thickness with a stripe Ti mask pattern is performed by hydride vapor phase epitaxy(HVPE). Ti strpie mask pattern is deposited by DC magnetron sputter on GaN epitaxial layer of $3{\mu}m$ thickness is grown by hydride vapor phase epitaxy(HVPE). Void are observed at point of Ti mask pattern when GaN layer is investigated by scanning electron microscope. The Crack of GaN layer is observed according to void when it is grown more thick GaN layer. The full width at half maximum of peak which is measured by X-ray diffraction is about 188 arcsec. It is not affected its crystallization by Ti meterial when GaN layer is overgrown on Ti stripe mask pattern according as it is measure FWHM of overgrowth GaN using Ti material against FWHM of first growth GaN epitaxial layer.

• Journal of the Korean Crystal Growth and Crystal Technology
• /
• v.8 no.3
• /
• pp.388-395
• /
• 1998

This paper reports on a thermodynamic analysis for the GaN thick film growth by vapor phase epitaxy method. The thermodynamic calculation was performed using a chemical stoichiometric algorism. The simulation variables include the growth temperature in a range 400~1500 K, the gas ratios $(GaCl_3)/(GaCl_3+NH_3)$ and $(N_2)/(GaCl_3+NH_3)$. The theoretical calculation predicts that the growth temperature of GaN be in the lower range of 450~750 K than the experimental results. The difference in the growth temperature between the simulation and the experiments indicates that the vapor phase epitaxy of GaN is kinetically limited, presumably, due to the high activation energy of thin film growth.

• Journal of the Korean Crystal Growth and Crystal Technology
• /
• v.19 no.1
• /
• pp.6-10
• /
• 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 Institute of Telematics and Electronics
• /
• v.23 no.6
• /
• pp.820-832
• /
• 1986

In contrast to conventional liquid phase epitaxy of GaAs, surface kinetics limited growth is predominant in selective liquid phase epitaxy. For the stripe openings in the high-index crystal-lographic directions, the well-known facet formations and the decompositions into the low index planes or smooth circular surfaces are observed depending on the growth kinetics. For the low index direction stripe, surface kinetics limited growth is evident. By a numerical calcualtion we show that these phenomena are due to the enhanced masstransport by two dimensional diffusion and growth rate anisotropy which is found to be very stdrong with cusped minima for some singular planes in the solution growth as well as in vapor phase epitaxy. Morphological stability is briefly treated in terms of diffusion and its implications on device application are stated. Tese phenomena may be common to III-V compound semiconductors as well as GaAs.