• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.31 no.5
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• pp.320-323
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• 2018

SiGe thin films were deposited by remote plasma enhanced chemical vapor deposition (RPE-CVD) at $400^{\circ}C$ using $SiH_4$ or $SiCl_4$ and $GeCl_4$ as the source of Si and Ge, respectively. The growth rate and the degree of crystallinity of the fabricated films were characterized by scanning electron microscopy and Raman analysis, respectively. The optical and electrical properties of SiGe films fabricated using $SiCl_4$ and $SiH_4$ source were comparatively studied. SiGe films deposited using $SiCl_4$ source showed a lower growth rate and higher crystallinity than those deposited using $SiH_4$ source. Ultraviolet and visible spectroscopy measurement showed that the optical band gap of SiGe is in the range of 0.88~1.22 eV.

• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.289.1-289.1
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• 2016

Germanium (Ge) with higher carrier mobility and a lower crystallization temperature has been considered as the channel material of thin-film transistors for display applications. Various methods were studied for crystallizaion of poly-Ge from amorphous Ge at low temperature. Especially Metal induced crystalliazation (MIC) process was widely studied because low process cost. In this paper, we investigate copper diffusion process of different thick (70 nm, 350 nm) poly-Ge film obtained by MIC process at various temperatures (250, 300, and $350^{\circ}C$) through atomic force microscopy (AFM), Raman spectroscopy, and secondary ion mass spectroscopy (SIMS) measurement. Crystallization completeness and grain size was similar in all the conditions. Copper diffusion profile of 370 nm poly-Ge film show simirly results regardless of process temperature. However, copper diffusion profile of 70 nm poly-Ge film show different results by process temperature.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.06a
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• pp.99-100
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• 2009

SGOI 1T-DRAM cells with various Ge mole fractions were fabricated and compared to the SOI 1T-DRAM cell. SGOI 1T-DRAM cells have a higher leakage current than SOI 1T-DRAM cell at subthreshold region. The leakage current due to crystalline defects and interface states at Si/SiGe increased with Ge mole. This phenomenon causes sensing margin and the retention time of SGOI 1T-DRAMs decreased with increase of Ge mole fraction.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2006.11a
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• pp.7-8
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• 2006

The effects of heat treatment on the electrical properties of SGOI were examined. We proposed the optimized heat treatments for improving the interfacial electrical properties in SGOI-MOSFET. By applying the additional pre-RTA(rapid thermal annealing) before gate oxidation and post-RTA after dopant activation, the driving current, the transconductance, and the leakage current were improved significantly.

• Proceedings of the Materials Research Society of Korea Conference
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• 2011.05a
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• pp.64.2-64.2
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• 2011

Recently, Silicon Germanium (SiGe) alloys have been received considerable attention for their great potentials in advanced electronic and optoelectronic devices. Especially, microcrystalline SiGe is a good channel material for thin film transistor due to its advantages such as narrow and variable band gap and process compatibility with Si based integrated circuits. In this work, microcrystalline silicon-germanium films (${\mu}c$-SiGe) were deposited by DC/RF magnetron co-sputtering method using Si and Ge target on Corning glass substrates. The film composition was controlled by changing DC and RF powers applied to each target. The substrate temperatures were changed from $100^{\circ}C$ to $450^{\circ}C$. The microstructure of the thin films was analyzed by x-ray diffraction (XRD) and Raman spectroscopy. The analysis results showed that the crystallinity of the films enhances with increasing Ge mole fraction. Also, crystallization temperature was reduced to $300^{\circ}C$ with $H_2$ dilution. Hall measurements indicated that the electrical properties were improved by Ge alloying.

• Journal of Environmental Science International
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• v.23 no.6
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• pp.995-1001
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• 2014

When relations improve between North and South Korea, there will be demand for North Korean edible plants because of the low labor cost and similar environmental conditions. However, there is no reliable information about trace elements, metals, and metalloids in edible plants from North Korea. Selenium (Se) and germanium (Ge) have positive effects on basic human health and are therapeutical in diverse illnesses. Metal and metalloid (Cd, Pb) poisoning, on the other hand, can cause many health problems. Plants collected from North Korea had higher selenium content than those from South Korea. Although none of the collected species exceeded the permissible levels of cadmium and lead, their content in plants was significantly higher in North Korea than in South Korea. The high metal contents in plants collected from North Korea may be associated with the soil physicochemical properties as well as the accumulated amounts of elements in the soil.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.11a
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• pp.86-87
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• 2008

In this study, we studied the nature of thin films formed by photodoping chalcogenide materials with for use in programmable metallization cell devices, a type of ReRAM. We investigated the resistance of Ag-doped chalcogenide thin films varied in the applied voltage bias direction from about 1 M$\Omega$ to several hundreds of $\Omega$. As a result of these resistance change effects, it was found that these effects agreed with PMC-RAM. The results imply that a Ag-rich phase separates owing to the reaction of Ag with free atoms from the chalcogenide materials.

• Journal of Radiation Protection and Research
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• v.26 no.3
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• pp.249-253
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• 2001

Neutron dose assessment in criticality accidents using Whole Body Counter (WBC) was proved to be an effective method as rapid neutron dose estimation at the JCO criticality accident in Tokai-mura. The 1.36MeV gamma-ray of $^{24}Na$ in a body can be detected easily by a germanium detector. The Minimum Detectable Activity (MDA) of $^{24}Na$ is approximately 50Bq for 10miniute measurement by the germanium-type whole body counter at JNC Tokai Works. Neutron energy spectra at the typical shielding conditions in criticality accidents were calculated and the conversion factor, whole body activity-to-organ mass weighted neutron absorbed dose, corresponding to each condition were determined. The conversion factor for uncollied fission spectrum is 7.7 $[(Bq^{24}Na/g^{23}Na)/mGy]$.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.02a
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• pp.384-384
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• 2012

PRAM switching device by using current pulse modulation was investigated to verify its possibility for 3D architecture. In this work, two phase change materials connected in series having a different crystallization temperature are used. Its structural for different phase change material was evaluated by electrical resistance. We confirmed that Germanium-Antimony-Tellurium (GST) alloy and Germanium- Copper-Tellurium (GCT) alloy material were selected according to crystallization temperature, ${\sim}180^{\circ}C$ for switching and ${\sim}240^{\circ}C$ for memory devices, respectively. From this research, it is expected that phase change switching device could have advantages of process in terms of material similarity and structural simplification.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.02a
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• pp.356-356
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• 2013

Monolithic 3D-IC는 현대 집적회로에서 interconnect로 인해 발생되는 여러 문제들을 해결하기 위해 새롭게 제시되고 있는 기술적 개념으로 구현 시 하위 소자 및 interconnet들에 영향을 주지 않는 저온공정이 필수적이다. 특히 germanium (Ge)은 낮은 녹는점 및 높은 캐리어 이동도 덕분에 3D-IC 구현 시 상위 소자의 channel 물질에 적합한 것으로 알려져 있다. 최근 이러한 Ge을 결정화하기 위해 solid phase crystallization (SPC), metal induced crystallization (MIC), laser annealing과 같은 결정화 방법들이 보고되고 있다. 현재까지 SPC 방법에 의해 얻어진 poly-Ge의 도핑농도 및 이동도와 같은 전기적 특성에 대한 분석은 수행된 바 있으나 3D-IC 공정에 적용이 가능한 MIC 기술을 통해 얻어진 poly Ge 필름에 대한 전기적 특성분석은 부족한 상황이다. 본 연구는 SPC 뿐만 아니라 MIC 방법을 통해 ${\alpha}$-Ge를 결정화시키고 얻어진 poly-Ge 필름의 전기적 특성을 XRD 및 hall effect measurement를 통해 분석하였다. 특히 일반적으로 Ge 내에서 p-type dopant로 동작을 하는 defect과 n-type dopant인 phosphorus 관계를 고려하여 여러 온도에서 SPC 및 MIC에 의해 얻어진 phosphorus doped poly-Ge 필름들의 전기적 특성을 분석하였다.