• 한국자기학회지
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• 제16권3호
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• pp.178-181
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• 2006

본 연구에선는 수직 Bridgman 법으로 묽은 자성 반도체 $Si_{1-x}Mn_xTe_{1.5} $ 단결정을 성장시켜 Mn의 조성비 변화에 따른 광학적, 전지적, 그리고 자기적 특성을 조사하였다. X-선 회절 실험으로부터 육방정계(hexagonal) 구조임을 확인하였다. 광흡수 측정으로부터 에너지 띠 간격은 조성비 x와 온도 증가에 대하여 감소함을 보였다. 성장시킨 시료의 경우 강자성 특성을 나타내었으며, Curie 온도는 80K 이상이었다. Mn의 조성비가 증가함에 따라 평균 자기 모멘트와 보자력 값은 증가하였다.

• 한국결정학회지
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• 제7권1호
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• pp.44-56
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• 1996

CuInTe2 다결정은 수평전기로에서 합성하고, CuInTe2 단결정은 수직 Bridgman 방법으로 성장하여 결정구조를 조사하고, Hall 효과를 30K에서 293K의 온도영역에서 측정하였다. CuInTe2 다결정 및 단결정은 정방정계였다. 다결정의 격자상수는 a=6.168Å, c=12.499Å 그리고 c/a=2.026이었고, 단결정의 격자상수는 a=6.186Å, c=12.453Å, 그리고 c/a=2.013이었다. CuInTe2 단결정의 성장면은 Laue 배면반사 사진으로부터 구하였으며 (112)면이었다. CuInTe2 단결정의 Hall 효과는 van der Pauw 방법으로 측정하였다. 상온에서 측정된 c축에 수직한 시료의 운반자농도 p는 2.14×1023holes/m3, 전기전도도 δ는 739.58Ω-1m-1 그리고 이동도 μ는 2.16×10 m2/V·s 이었다. c축에 평행한 시료의 운반자농도 p는 1.51×1023holes/m3, 전기전도도 σ는 717.55Ω-1m-1 그리고 이동도 μ는 2.97×10-2 m2/V·s이었다. c축에 수직 및 평행한 시료의 Hall계수가 양의 값이어서 CuInTe2 단결정은 p형 반도체임을 알 수 있었다.

• 한국진공학회지
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• 제2권1호
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• pp.65-72
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• 1993

MgGa2-xInxSe4 single crystal을 bridgman technique로 성장시켰다. 성장된 단결정은 rhombohedral 구조를 가지고 있었으며, lattice constant는 a=3.950~4.070$\AA$, c=38.89~39.50$\AA$으로 주어졌고, 높은 photoconductivity를 가지고 있었다. 이 단결정의 energy gap은 2.20~1.90eV이었고, photoconductivity spectrum에 peak의 energy는 2.31~2.01eV로 주어졌으며, photoconductivity의 time constant는 0.24~0.34sec로 주어졌다.

• 한국결정학회지
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• 제1권2호
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• pp.115-125
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• 1990

We have investigated bulk and hetero-epitaxial growth of GaAs single crystal. Various growth techniques such as HB, HZM, and VGF for high quality bulk GaAs were successfully developed by appling the specially designed DM(direct monitoring) furnace. Al GaAs/GaAs superlattice structure and In(x)Ga(1-x) As/GaAs epilayers were also grown by MOCVD and VPE, respectively. The characterization of GaAs single crystals and epilayers was made by X-ray diffraction, Hall effect, PL, chemical etching and angle lapping technique.

• JSTS:Journal of Semiconductor Technology and Science
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• 제1권1호
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• pp.40-49
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• 2001

We have developed a repeatable process of forming uniform, small-size and high-density self-assembled Si nano-crystals. The Si nano-crystals were fabricated in a conventional LPCVD (low pressure chemical vapor deposition) reactor at $620^{\circ}c$ for 15 sec. The nano-crystals were spherical shaped with about 4.5 nm in diameter and density of $5{\times}l0^{11}/$\textrm{cm}^2$. More uniform dots were fabricated on nitride film than on oxide film. To take advantage of the above-mentioned characteristics of nitride film while keeping the high interface quality between the tunneling dielectrics and the Si substrate, nitride-oxide tunneling dielectrics is proposed in n-channel device. For the first time, the single electron effect at room temperature, which shows a saturation of threshold voltage in a range of gate voltages with a periodicity of ${\Delta}Ｖ_{GS}\;{\approx}\;1.7{\;}V$, corresponding to single and multiple electron storage is reported. The feasibility of p-channel nano-crystal memory with thin oxide in direct tunneling regime is demonstrated. The programming mechanisms of p-channel nano-crystal memory were investigated by charge separation technique. For small gate programming voltage, hole tunneling component from inversion layer is dominant. However, valence band electron tunneling component from the valence band in the nano-crystal becomes dominant for large gate voltage. Finally, the comparison of retention between programmed holes and electrons shows that holes have longer retention time.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1998년도 추계학술대회 논문집 학회본부 C
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• pp.726-728
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• 1998

Optical and electrical properties of GaSe:$Er^{3+}$ single crystals grown by the Bridgeman technique was been investigated by using optical absorption and Hall-effect measurements. The Hall coefficients were measured by using a high impedance electrometer in the temperature range from 360K to 150K. The temperature dependence of hole concentration shows the characteristic of a partially compensated p-type semiconductor. carrier density($N_H$) of GaSe doped with Erbium was measured about $3.25{\times}10^{16}\;[cm^{-3}}$ at temperature 300K, which was high than undoped specimen. Photon energy gap ($E_{gd}$) was measured about 1.7geV.

• 한국전기전자재료학회논문지
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• 제13권1호
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• pp.1-5
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• 2000

Optical and electrical properties of GaSe:Er\ulcorner single crystals grown by the Bridgenman technique have been investigated by using optical absorption and h\Hall-effect measurement system. The Hall coefficients were mea-sured by using a high impedance electrometer in the temperature range from 360K to 150K. The temperature dependence of hole concentration show the characteristic of a partially compensated p-type semiconductor. Carrier density(N\ulcorner) of GaSe doped with Erbium was measured about 3.25$\times$10\ulcorner [cm\ulcorner] at temperature 300K, which was higher than undoped specimen. Photon energy gap (E\ulcorner) of GaSe:Er\ulcorner specimen was measured about 1.79eV.

• Bulletin of the Korean Chemical Society
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• 제10권1호
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• pp.30-32
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• 1989

Traces of nine elements, gold, arsenic, cobalt, chromium, copper, europium, hafnium, sodium and antimony in commercially available silicon crystals were determined by the instrumental neutron activation analysis using the single comparator method. The values of the concentrations of these elements in both single and polycrystals were found to decrease significantly to a low limiting level by simply washing and etching surface contaminants having been introduced during various steps of sample preparation and irradiation. However, the chromium levels in polycrystals were not easily decreased, these depending upon the cutting tools employed. The Sb-doped content in each semiconductor has been compared with the associated quantities such as the concentration and the conductivity range given by the sample donor. Uncertainty in the sodium analysis due to the fission neutron reaction by silicon itself was discussed.

• 한국전기전자재료학회논문지
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• 제35권6호
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• pp.626-630
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• 2022

A 100 mm × 50 mm-sized (100) gallium oxide (Ga₂O₃) single crystal ingot was successfully grown by edge-defined film-fed growth (EFG). The preferred orientation and the quality of grown Ga₂O₃ ingot were compatible with a commercial Ga₂O₃ substrate by showing strong (100) orientation behaviors and 246 arcsec in X-ray rocking curve. Raman characterization was also performed for both samples; thereby providing various Raman-active characteristics of Ga₂O₃ crystals. In particular, we observed A_g(5) and A_g(10) peaks of Raman active mode, directly related to the impurity of the grown Ga₂O₃ crystal. Hence, the comparison of the crystal quality and Raman analysis might be useful for further enhancement of Ga₂O₃ single crystal quality in the future.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2000년도 학술대회 논문집 전문대학교육위원
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• pp.35-39
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• 2000

$ZnIn_2S_4$ and $ZnGaInS_4:Er^{3+}$ single crystals crystallized in the rhombohedral (hexagonal) space group $C_{3v}^5(R3m)$, with lattice constants $a=3.852{\AA},\;c=37.215{\AA}$ for $ZnIn_2S_4$, and $a=3.823{\AA}$, and $c=35.975{\AA}$ for $ZnIn_2S_4:Er^{3+}$. The optical absorption measured near the fundamental band edge showed that the optical energy band structure of there compounds had a direct and indirect band gap, the direct and indirect energy gaps are found to be 2.778 and 2.682 eV for $ZnIn_2S_4$, and 2.725 and 2.651eV for $ZnIn_2S_4:Er^{3+}$ at 293 K. The photoluminescence spectra of $ZnIn_2S_4:Er^{3+}$ measured in the wavelength ranges of $500nm{\sim}900nm$ at 10 K. Eight sharp emission peaks due to $Er^{3+}$ ion are observed in the regions of $549.5{\sim}550.0nm,\;661.3{\sim}676.5nm$, and $811.1{\sim}834.1nm$, and $1528.2{\sim}1556.0nm$ in $CdGaInS_4:Er^{3+}$ single crystal. These PL peaks were attributed to the radiative transitions between the split electron energy levels of the $Er^{3+}$ ions occupied at $C_{2v}$, symmetry of the $ZnIn_2S_4$ single crystals host lattice.