• Journal of the Korean Vacuum Society
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• v.6 no.S1
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• pp.59-65
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• 1997

Efficient Si(100) etching by thermal H atoms at low substrate temperatures has been achieved. Gas-phase etching product $SiH_4$(g) upon H atom bombardment resulting from direct abstraction of $SiH_3$(a) by impinging H atoms was detected with a quadrupole mass spectrometer over the substrate temperature range of 105-408 K Facile depletion of all surface silyl ($SiH_3$) groups the dissociative adsorption product of disilane ($Si_2H_6$) at 105K from Si(100)2$\times$1 by D atoms and continuous regeneration and removal of $SiD_3$(a) were all consumed. These results provide direct evidence for efficient silicon surface etching by thermal hydrogen bombardment at cryogenic temperatures as low as 105K We attribute the high etching efficiency to the formation and stability of $SiH_3$(a) on Si(100) at lowered surface temperatures allowing the $SiH_3$(a) abstraction reaction by additional H atom to produce $SiH_4$((g).

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.06a
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• pp.197-198
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• 2008

이 논문에서는 다양한 SiNx의 band gap을 이용하여 MIS 구조의 메모리 소자를 제작하고 이를 분석하였다. SiNx 박막은 증착 가스비에 따라 다양한 band gap을 가지게 된다. 본 실험에서는 $SiH_4$ 가스와 $NH_3$ 가스를 사용하여 SiNx 박막을 증착하였다. n-type 단결정 실리콘 기판위에 다양한 가스비에 따라 단일 SiNx 박막을 증착 및 분석하였고, 이를 이용하여 NNN 구조의 MIS 소자를 제작하였다. 제작된 소자는 4.6 V의 hysteresis roof 폭과 1000 초 후에 84.8 %의 retention 값을 갖는 우수한 메모리 특성을 보였다.

• Journal of Korean Medical classics
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• v.9
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• pp.381-429
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• 1996

Choo-Joo(鄒澍;1790-1844) was the medicine scholar who lived in the late peroid of the Chung-Dynasty and wrote "Bon-Kyung-So-Jeung(本經疏證)", "Bon-kyung-Sok-So(本經續疏)", "Bon-Kyng-Seo-So-Yo(本經序疏要)". In the books mentioned above, He annotated the chief effectiveness of herbal medicine(本草) which had been presented on "Shin-Nong-Bon-Cho-Kyung(神農本草經)" and "Myoung-Eui-Byul-Lok(名醫別錄)". He defined medical action of 315 herb-items with the many theories of various scholars. Scholars whom Choo-Joo has qoutated belong to the school of study of Chinese classics, and they have regarded "Hwang-Je-Nae-Kyung(黃帝內經)", "Shin-Nong-Bon-Cho-Kyung(神農本草經)" and "Sang-Han-Lon(傷寒論)" as great important cannon and have lived during the Myoung Chung Dynasty. The distinctive character of Choo-Joo belongs to similar academic traditions. It seems that he was appected mainly by "Bon-Cho-Gang-Mok(本草綱目)" written by Lee-Si-Jin(李時珍), Mok-Jung-Soon(繆仲淳)'s "Sin-Nonng-Bon-Cho-Kyung-So(神農本草經疏)", You-Yak-Guem(劉若金)'s "Bon-Cho-Sul(本草述)" and Yang-Si-Tae(楊時泰)'s "Bon-Cho-Sul-Gu-Won(本草述鉤元)". He contributed in two big sides. First, Choo-Joo(鄒澍) have achieved much contribution in biliographical study of Chinese classics(考證學). He analyzed the medical theory of herb-medicine, combining with "Nae-Kyung(內經)", "Sang-Han-Lon(傷寒論)" and many theory of various scholars in order to make research on the chief effectiveness that had been presented in "Shin-Nong-Bon-Cho-Kyung(神農本草經)". Therefore the practical application of medical theory and term which had been represented on classics were offered. Secondary, Choo-joo did great accomplishment in pharmacology. The point of his theory was grasping the effect of a medicine through distinctive one beyond general feature. He set up standards that grasp distintive feature as form, color, energy and taste, place of production and temper. And on the basis of these standards he investigated distinctive feature on various fields, then he induced 'the Uem-Yang-0-Haeng Theory(陰陽五行說)' from distictions. According to the these method of classification, form(形) stand for the resultant shape of herbal function, color(色) represent the active direction of herb, energy and taste(氣味) imply the ultimate active function of herb, the place of production(産地) and the period of occurrence(發生時期) symbolize symptoms. When he applied these method to seek for effetiveness, he regarded the field which revealed most representative feature as of great importance, and Combining remained distinctions with one another, he determined more accurate medicinal value. These method of obsevation solved contradiction which occured by equaly appling all medical herbs for the regular standard. The most important theory that represented in Choo-Joo(鄒澍) is to induce and to certify the distintive feature of herb into the 'Uem-Yang-0-Haeng Theory'. That is, concluded as "spring(生), growing(長), change(化), collecting(收) and storing(藏)". As the results of these studies, he made clear the action of medicine more concretly and made 'the Uem-Yang-0-Haeng Theory(陰陽五行說)' more concret and actual for applying. And he contrbuted to establish the standard for grasping the effect of medicines.

• Proceedings of the Korea Association of Crystal Growth Conference
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• 1997.06a
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• pp.261-263
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• 1997

6H-SiC single crystals were successfully grown by the self-designed sublimation apparatus and the optimum growth condition was established. The grown SiC crystals were about 33mm in diameter and 10mm in length. Carrier concentration and doping type of undopped 6H-SiC wafer grown by sublimation method were 1016∼1017/㎤ and n-type Crystallinity of grown 6H-SiC wafer was better than of Acheson seed by data of Raman spectroscopy and Double Crystal XRD. We continue to characterize the grown 6H-SiC wafer in more detail and so we will grow the high-quality 6H-SiC single crystal wafer.

• Journal of the Korean Vacuum Society
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• v.21 no.2
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• pp.99-105
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• 2012

We fabricated the textured silicon (Si) surface on Si substrates by the electrochemical etching using gold (Au) nanoparticle catalysts. The antireflective property of the fabricated Si nanostructures was improved. The Au nanoparticles of ~20-150 nm were formed by the rapid thermal annealing using thermally evaporated Au films on Si. In the chemical etching, the aqueous solution containing $H_2O_2$ and HF was used. In order to investigate the effect of electrochemical etching on the etching depth and reflectance characteristics, the sample was immersed in the aqueous etching solution for 1 min with and without applied cathodic voltages of -1 V and -2 V. As a result, the solar weighted reflectance, i.e., the averaged reflectance with considering solar spectrum (air mass 1.5), could be efficiently reduced for the electrochemically etched Si by applying the cathodic voltage of -2 V, which is expected to be useful for Si solar cell applications.

• 한국신재생에너지학회:학술대회논문집
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• 2011.05a
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• pp.129.2-129.2
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• 2011

본 연구에서는 a-Si:H/c-si 구조의 이종접합 태양전지의 p a-Si:H 에미터 층의 박막 조건에 따라 태양전지 특성을 연구하였다. p, n-layer는 PECVD (Plasma-enhanced chemical vapor deposition) i-layer는 HWCVD(Hot wire chemical vapor deposition), ITO는 RF 마그네트론 스퍼터링법으로 제작하였다. p-layer의 도핑 농도, 기판 증착 온도, 증착 높낮이에 따라 특성을 비교 분석 하였다. QSSPC로 minority carrier life time, 자외 가시선 분광분석 장치로 투과 반사도를, Ellipsometer로 흡수 계수, 두께, FTIR로 막의 구성요소 등의 변화를 조사하여 개선된 p a-Si:H의 특성이 이종접합 태양전지에서 효율향상에 영향을 주는지 Photo IV와 EQE를 통하여 조사하였다.

• Proceedings of the Korea Association of Crystal Growth Conference
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• 1998.09a
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• pp.35-40
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• 1998

There have two kinds of defects, planar defects and vertical defects which were called micropipes in SiC bulk crystals grown by a sublimation method. We could decrease these defects by adding a little piece of Si in the SiC powder or using Ta cylinder in the crucible. so were report the dependence of these defects in a wafer on silicon/carbon ratio in this paper. The chemical species sublimed from SiC powder is affected by carbon from the graphite wall of the crucible. It is important to control the chemical species on the substrate.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.24 no.2
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• pp.128-135
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• 2013

This letter presents the MISHFET with si-doped AlGaN/GaN heterostructure for power amplifier. The device grown on 6H-SiC(0001) substrate with a gate length of 180 nm has been fabricated. The fabricated device exhibited maximum drain current density of 837 mA/mm and peak transconductance of 177 mS/mm. A unity current gain cutoff frequency was 45.6 GHz and maximum frequency of oscillation was 46.5 GHz. The reported output power density was 1.54 W/mm and A PAE(Power Added Efficiency) was 40.24 % at 9.3 GHz.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.07b
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• pp.1092-1095
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• 2004

The $ZnGa_2O_4$ phosphor target is synthesized through solid-state reactions as calcine and sintering temperature in order to deposit $ZnGa_2O_4$ phosphor thin film by rf magnetron sputtering system. The $ZnGa_2O_4$ phosphor thin film is deposited on $Pt/Ti/SiO_2/Si$ substrate and prepared $ZnGa_2O_4$ Phosphor thin film is annealed by rapid thermal processor(RTP) at $750^{\circ}C$, 10 sec. The x-ray diffraction patterns of $ZnGa_2O_4$ phosphor target and thin film show the position of (311) main peak. The cathodolumincsccnce(CL) succtrums of $ZnGa_2O_4$ phosphor target show main peak of 360nm and broad bandwidth of about 180nm.

• Proceedings of the KIEE Conference
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• 2000.07c
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• pp.1803-1805
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• 2000

This paper analyzes the effects of Ge profiles shape of SiGe heterojunction bipolar transistors (HBT's) for high frequency application. Device simulations using ATLAS/BLAZE for the SiGe HBT with trapezoidal or triangular Ge profile are carried out to optimize the device performance. An HBT with 15% triangular Ge profile shows higher cut-off frequency and DC current gain than that with 19% trapezoidal Ge profile. The cut-off frequency and BC gain are increased from 42GHz to 84GHz and from 200 to 600, respectively.