• Bulletin of the Korean Chemical Society
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• 제33권1호
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• pp.153-158
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• 2012

The hydrogenation of $AlB_2$-type BaGaGe exhibits a metal to insulator (MI) transition, inducing a puckering distortion of the original hexagonal [GaGe] layers. We investigate the electronic structure changes associated with the hydrogen-induced MI transition, using extended H$\ddot{u}$ckel tight-binding band calculations. The results indicate that hydrogen incorporation in the precursor BaGaGe is characterized by an antibonding interaction of $\pi$ on GaGe with hydrogen 1s and the second-order mixing of the singly occupied antibonding $\pi^*$ orbital into it, through Ga-H bond formation. As a result, the fully occupied bonding $\pi$ band in BaGaGe changes to a weakly dispersive band with Ge pz (lone pair) character in the hydride, which becomes located just below the Fermi level. The Ga-Ge bonds within a layered polyanion are slightly weakened by hydrogen incorporation. A rationale for this is given.

• 한국재료학회지
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• 제18권6호
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• pp.302-306
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• 2008

Polycrystalline germanium (Ge) thin films were grown by metal organic chemical vapor deposition (MOCVD) using tetra-allyl germanium [$Ge(allyl)_4$], and germane ($GeH_4$) as precursors. Ge thin films were grown on a $TiN(50nm)/SiO_2/Si$ substrate by varying the growth conditions of the reactive gas ($H_2$), temperature ($300-700^{\circ}C$) and pressure (1-760Torr). $H_2$ gas helps to remove carbon from Ge film for a $Ge(allyl)_4$ precursor but not for a $GeH_4$ precursor. $Ge(allyl)_4$ exhibits island growth (VW mode) characteristics under conditions of 760Torr at $400-700^{\circ}C$, whereas $GeH_4$ shows a layer growth pattern (FM mode) under conditions of 5Torr at $400-700^{\circ}C$. The activation energies of the two precursors under optimized deposition conditions were 13.4 KJ/mol and 31.0 KJ/mol, respectively.

• 한국재료학회:학술대회논문집
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• 한국재료학회 2007년도 추계학술발표대회 및
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• pp.60.2-60.2
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• 2007

• Applied Science and Convergence Technology
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• 제24권4호
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• pp.90-95
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• 2015

The adsorption behavior of tris (dimethylamino)-cyclopentadienyl-zirconium (Cp-Zr) precursor using an in-situ attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FT-IR) was studied. In attempt to improve the detection intensity of an adsorbed precursor, nanoparticles were uniformly distributed on the Ge ATR crystal surface employing the spray method. The absorption characteristics studies were carried out over the Ge crystal temperature in the range of $30{\sim}50^{\circ}C$. Upon increasing the temperature, a reduction of absorption was observed. Based on the peak intensities of ATR-FT-IR spectroscopy, higher-$ZrO_2$ absorption efficiency occurs when the nano-particles are utilized compared to pure Ge crystal.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2009년도 제37회 하계학술대회 초록집
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• pp.238-238
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• 2009

• 자원환경지질
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• 제42권5호
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• pp.501-507
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• 2009

본 연구에서는 단일 벽(Single-wall) 구조를 갖는 나노크기의 속이 빈(hollow) 볼(Ball)형(NBs; Nano-balls), 짧은 길이 튜브(S-NTs; Short-fiber Nano-tubes)형 및 긴 길이 튜브(L-NTs; Long-fiber Nano-tubes) 물질을 동일한 조성 Al/Ge=1.33을 갖는 Aluminogermanate(ALGE) Precursor 최초 혼합용액의 단순한 pH 조절 과정에서 자기조합(Self-assembly)을 통해 성공적으로 합성하였다. 먼저 pH=13으로의 염기성화(Na/Al=28~30) 및 최종 pH=9 조건에서 5 nm의 균질한 크기를 갖으며, 화학조성인 Al/Ge=1.5~1.6인 속이 빈 구조의 NBs가 합성되었다. pH=13으로의 염기성화 및 최종 pH=4 조건에서는 3.3 nm 지름, 길이 15~20 nm, Al/Ge=2.6~2.8의 S-NTs가 합성되었다. 그러나 pH=9로 염기성화(Na/Al=3.8) 시킨 후 최종 pH=4조건에서는 나노-튜브의 길이가 100 nm 이상인 L-NTs가 처음으로 합성되었다. 이러한 결과는 ALGE Precursor로부터 -Ge-OH 표면에서의 $H^+$-dissociation 정도 차이, 즉, $Na^+$ 양 및 최종 pH 조건을 달리함으로써 의도하는 형태의 ALGE 나노물질 유도가 가능함을 시사한다.

• 한국전기전자재료학회논문지
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• 제21권5호
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• pp.411-414
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• 2008

The germanium films were deposited by metal organic chemical vapor deposition using $Ge(allyl)_4$ precursors on TiAlN substrates. Deposition of germanium films was only possible with a presence of $Sb(iPr)_3$, which means that $Sb(iPr)_3$ takes a catalytic role by a thermal decomposition of $Sb(iPr)_3$ for Ge film deposition. Also, as Sb bubbler temperature increases, deposition rate of the Ge films increases at a substrate temperature of $370^{\circ}C$. The GeTe thin films were fabricated by MOCVD with $Te(tBu)_2$ on Ge thin film. The GeTe films were grown by the tellurium deposition at $230-250^{\circ}C$ on Ge films deposited on TiAlN electrode in the presence of Sb at $370^{\circ}C$. The GeTe film growth on Ge films depends on the both the tellurium deposition temperature and deposition time. Also, using $Sb(iPr)_3$ precursor, GeSbTe films with hexagonal structures were fabricated on GeTe thin films. GeSbTe films were deposited in trench structure with 200 nm*120 nm small size.

• Journal of Ceramic Processing Research
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• 제13권spc1호
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• pp.110-113
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• 2012

Ge-S and Li-Ge-S powders were synthesized via solution-based process in order to employ chalcogenide-based solid electrolyte for use in Li secondary batteries. GeCl4 and thioacetamide in combination result in Ge-S powders of which major crystalline phase becomes GeS2 where the tetragonal and orthorhombic phases coexist after heat treatment. A chemical treatment using NaOH brings about the reduction of chlorine in the powders obtained. However, the heat treatment at 300 ℃ is more effective in minimizing the chlorine content. When lithium chloride is used as the precursor of Li ions, the LiCl powders are agglomerated with an inhomogeneous distribution. When Li2S is used, the Li-Ge-S powders are distributed more uniformly and the orthorhombic GeS2 phase dominates in the powders.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2013년도 제44회 동계 정기학술대회 초록집
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• pp.250-250
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• 2013

본 연구에서는 차세대 상변화메모리(PCRAM)와 초고속 소자(FET) 등의 응용을 위하여 사용되고 있는 Ge 소재를 제조하기 위해새롭게 전구체를 개발하고 이를 CVD (Chemical Vapor Deposition) 공정을 이용하여 증착실험을 실시하였다. 새롭게 개발된 Ge 전구체 (isopropyl germane)는 기존 Ge 전구체보다 합성비용이 경제적이며 공정이 간단하고 상업적 생산에도 적합하다는 장점을 갖고 있다. Ge 박막의 증착은 증착압력, 증착온도, reactive gas (H2) 유량, carrier gas(Ar) 유량, 기판(Si, Pt 등) 등을 변수로 하여 실험하였다. 증착된 박막에 대하여 FE-SEM, XRD 등을 통하여 기본적인 물성분석을 실시하였다.

• 한국초전도ㆍ저온공학회논문지
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• 제21권2호
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• pp.36-39
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• 2019

Effects of the spherically shaped Ge and the rod-like carbon-coated Ge on the superconducting properties of $MgB_2$ were investigated. Pure Ge and carbon-coated Ge nano-powders were synthesized under the different amount of $CH_4$ (0 to 5 kPa) by using DC thermal plasma method. When the $CH_4$ was added ~100 nm sized Ge with a spherical shape changed to rod-like morphology with a diameter of ~30-70 nm and a length of ~400-500 nm. Also it was confirmed that thin carbon layers of a few nanometers were formed along the rod length and the agglomerated carbons were found on the edges of rods. Pure spherical Ge and Ge/C rods were mixed and milled with Mg & B precursor to form the doped $MgB_2$ bulk samples by the solid-state reaction method. Almost no change of $T_c$ was noticed for the pure Ge-added $MgB_2$, whereas $T_c$ was found to decrease with the Ge/C-added $MgB_2$ samples. It was found that the pure spherical Ge showed to have a negative effect on the flux pinning of $MgB_2$. However, Ge/C rods can enhance the flux pinning property of $J_c$ due to the coated carbon on Ge rods.