• Journal of the Korean Crystal Growth and Crystal Technology
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• v.21 no.3
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• pp.99-104
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• 2011

A stoichiometric mixture of evaporating materials for $MgGa_2Se_4$ single crystal thin films was prepared from horizontal electric furnace. The crystal structure of these compounds has a rhombohedral structure with lattice constants $a_0=3.953\;{\AA}$, $c_0=38.890\;{\AA}$. To obtain the single crystal thin films, $MgGa_2Se_4$ mixed crystal was deposited on thoroughly etched semi-insulating GaAs(100) substrate by the Hot Wall Epitaxy (HWE) system. The source and substrate temperatures were $610^{\circ}C$ and $400^{\circ}C$, respectively. The crystalline structure of the single crystal thin films was investigated by the double crystal X-ray rocking curve and X-ray diffraction ${\omega}-2{\theta}$ scans. The carrier density and mobility of $MgGa_2Se_4$ single crystal thin films measured from Hall effect by van der Pauw method were $6.21{\times}10^{18}\;cm^{-3}$ and 248 $cm^2/v{\cdot}s$ at 293 K, respectively. The optical absorption of $MgGa_2Se_4$ single crystal thin films was investigated in the temperature range from 10 K to 293 K. The temperature dependence of the optical energy gap of the $MgGa_2Se_4$ obtained from the absorption spectra was well described by the Varshni's equation, $E_g(T)=E_g(0)-({\alpha}T^2/T+{\beta})$. The constants of Varshni's equation had the values of $E_g(0)=2.34\;eV$, ${\alpha}=8.81{\times}10^{-4}\;eV/K$ and ${\beta}=251\;K$, respectively.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.13 no.3
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• pp.122-126
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• 2003

In this study, $Zn_{0.86}Mn_{0.14}$Te epilayer of 0.7 $\mu\textrm{m}$-thickness was grown on GaAs(100) substrate by using hot wallepitaxy. GaAs(100) substrate was removed from $Zn_{0.86}Mn_{0.14}$Teepilayer by the selective etching solution. The crystal structure and the lattice constant of only Z $n_{0.86}$ M $n_{0.14}$Te epilayer were investigated to be zincblende and 6.140 $\AA$ from X-ray diffraction pattern, respectively. Mn composition x of $Zn_{1-x}Mn_x$Te epilayer was found to be 0.14 using this lattice constant and Vegard's law. The crystal quality of the epilayer was confirmed to be very good due to 256 arcsec-full-width at half-maximum of the double crystal rocking curve. The absorption spectra from the transmission ones were obtained to measure the band gap energy of $Zn_{0.86}Mn_{0.14}$Te epilayer from 300 K to 10 K. With the decreasing temperature,. strong absorption regions in the absorption spectra were shifted to higher energy side and the absorption peak meaning the free exciton formation appeared near the absorption edge. The band gap energy values of $Zn_{0.86}Mn_{0.14}$Te epilayer at 0 K and 300 K were found to be almost 2.4947 eV and 2.330 eV from the temperature dependence of the free exciton peak position energy of $Zn_{0.86}Mn_{0.14}$Te epilayer, respectively. The free exciton peak position energy of $Zn_{0.86}Mn_{0.14}$Te epilayer without GaAs substrate was larger 15.4 meV than photoluminescence peak position energy at 10 K. This energy difference between two peaks was analysed to be Stokes shift.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.25 no.2
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• pp.51-55
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• 2015

The present research is focused on the effect of porous graphite what is influenced on the 4H-SiC crystal growth by PVT method. We expect that it produces more C-rich and a change of temperature gradient for polytype stability of 4H-SiC crystal as adding the porous graphite in the growth cell. The SiC seeds and high purity SiC source materials were placed on opposite side in a sealed graphite crucible which was surrounded by graphite insulator. The growth temperature was around $2100{\sim}2300^{\circ}C$ and the growth pressure was 10~30 Torr of an argon pressure with 5~15 % nitrogen. 2 inch $4^{\circ}$ off-axis 4H-SiC with C-face (000-1) was used as a seed material. The porous graphite plate was inserted on SiC powder source to produce a more C-rich for polytype stability of 4H-SiC crystal and uniform radial temperature gradient. While in case of the conventional crucible, various polytypes such as 6H-, 15R-SiC were observed on SiC wafers, only 4H-SiC polytype was observed on SiC wafers prepared in porous graphite inserted crucible. The defect level such as MP and EP density of SiC crystal grown in the conventional crucible was observed to be higher than that of porous graphite inserted crucible. The better crystal quality of SiC grown using porous graphite plate was also confirmed by rocking curve measurement and Raman spectra analysis.

• Journal of Veterinary Clinics
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• v.20 no.3
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• pp.286-293
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• 2003

The cardiopulmonary and antagonistic effects of atipamezole, to medetomidine (30 ug/kg, IM)-tiletamine/zolazepam (10 mg/kg, IV) were determined. Twelve healthy mongrel dogs ,(4.00$\pm$0.53 kg, mean$\pm$SD) were randomly assigned to the four experimental groups (control, A30; atipamezole 30 ug/kg, A60; atipamezole 60 ug/kg, A150; atipamezole 150 ug/kg) with 3 dogs in each group. Atropine (0.03 mg/kg, IM), medetomidine, and tiletamine/zolazepam (TZ) were injected 10 minute intervals. Atipamezole was injected intravenously 15 minutes after TZ injection. Mean arousal time (MAT) was 52.50$\pm$4.98, 43.06$\pm$2.60, 32.83$\pm$8.13, and 14.36$\pm$1.60 minutes in control, A30, A60, and Al50 groups respectively. In Al50 group, MAT was significantly reduced (P < 0.05). but mean walking time (MWT) was similar to that in control group. In recovery period, the higher doses of atimapezole, the rougher recovery including head rocking, hypersalivation, and muscle twitching. Five of twelve dogs vomited within 5 minutes after medetomidine injection. In Control group, heart rate significantly decreased in all recording stages except 15 minutes after TZ injection, 10 minutes after medetomidine injection in all groups, and 40 minutes after atipamezole injection in A30 group (P < 0.05). In Al50 group, atipamezole reversed the respiratory depression induced by medetomidine. Arterial blood pressure was significantly decreased 10minutes after medetomidine injection and 15 minutes after TZ injection in almost dogs in this study (P < 0.05). From 10 minutes after atipamezole injection to arousal time, arterial blood pressure was progressively increased in A60 and A150 group. Any value of blood gas analysis and CBC, and serum chemistry values were not significantly changed except pH of Al50 at 10 minutes after medetomidine injection. As shown in present study, atipamezole(150 ug/kg) is considered to exert a useful reversal effect in dogs anesthetized with medetomidine-tiletamine/zolazepam combination.

• Journal of Veterinary Clinics
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• v.20 no.1
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• pp.33-41
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• 2003

The cardiopulmonary and anesthetic effects of tiletamine/zolazepam(TZ, 10 mg/kg IV), xylazine-tiletamine /zolazepam(XTZ, X: 1.1 mg/kg IM, TZ: 10 mg/kg IV) and medetomid-ine-tiletamine/zolazepam(MTZ, M: 30$\mu\textrm{g}$/kg IM, TZ: 10 mg/kg IV) were evaluated to 15 healthy mongrel dogs (4.16$\pm$0.65 kg). These dogs were randomly assigned to the three treatment groups(Control, XTZ, MTZ) with 5 dogs in each group. All experimental animals were premedicated with atropine(0.03 mg/kg, IM). Xylazine or medetomidine were administered to dogs in XTZ group and MTZ group 10 minutes after atropine injection. TZ was administered 20 minutes after atropine injection in all groups. The loss of pain response at pedal reflex and ear pinching tests in XTZ and MTZ groups were much longer compared with those of Control group(P < 0.01). All dogs in this study showed head rocking and hypersalivation during recovery time. Body temperature decreased progressively during experimental period in all groups, but it was not significant. After TZ injection, heart beat rate significantly increased 10 and 20 minutes in Control group, and 20 and 40 minutes in XTZ group(P < 0.05). Respiratory rate significantly decreased 0,10,20 and 40 minutes after 72 injection in XTZ and MTZ groups. In Control group, systolic arterial pressure (SAP) 20 minutes. diastolic arterial pressure(DAP) 10 minutes and mean arterial pressures (MAP) 10 and 20 minutes after 72 injection significantly decreased(P < 0.05). In XTZ group, SAP, DAP and MAP significantly decreased 20 and 40 minutes after 72 injection(P < 0.05). Thus, it was considered that XTZ and MTZ were useful in a canine surgical treatment that requires long anesthetic duration and deep analgesia.