http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
형정환,김길성,Alok Kumar Rai,Chan-Oh Jang,Chan-Yang Lee,Zagarzusem Khurelbaatar,Susant Kumar Acharya,이상권 한국물리학회 2012 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.60 No.1
One-dimensional (1D) single crystalline tellurium (Te) micro- and nanostructures were successfully prepared using thermal evaporation with a metallic Te powder. We found that the morphologies of the Te structures evolved from microrods to nanorods and finally tubular nanostructures with increasing growth temperatures of 500, 600, and 700 C. Our results strongly suggest that the growth temperature, which highly depends on the formation of a two-dimensional (2D) Te microcrystal layer on the substrate, plays an important role in determining the surface morphology and the crystal orientation of the Te micro- and nanostructures.
형정환,M. Shaheer Akhtar,Dong-Joo Kim,양오봉,이상권 한국물리학회 2009 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.55 No.1
We report on ZnO nanowires (ZnO NWs), which were grown on the surface of a TiO2 thin-film electrode with zinc dihydrate acetate seeds by using thermal chemical vapor deposition. Detailed morphological properties revealed that the grown ZnO NWs fully covered the surface of the TiO2 thin-film electrode. The grown ZnO-NW-covered TiO2 thin films (ZnO NW/TiO2 thin-film) were used as working electrodes in dye-sensitized solar cells (DSSCs). We observed that a covering of ZnO NWs on the TiO2 thin-film electrodes improved the open-circuit voltage VOC and the fill factor FF while significantly decreasing the short-circuit current density JSC the and photovoltaic performance of the ZnO NW/TiO2 thin-film DSSCs compared to there for bare TiO2 thin-film DSSCs. The VOC and the FF of the ZnO NW/TiO2 thin-film based DSSCs were enhanced by about 10 − 15% compared to the values for bare TiO2 thin-film DSSCs. One can attribute the enhanced VOC and FF to the larger size of upstanding ZnO NWs on the TiO2 thin-film substrate, which slow surface recombination between the anode electrode and the electrolyte.
탄화규소 (3C-SiC) 나노선 트랜지스터의 제작 및 2D ATLAS 시뮬레이션 비교 연구
김동주,이승용,형정환,이상권 한국물리학회 2008 새물리 Vol.57 No.5
We report on the electrical characteristics of 3C-SiC nanowire (NW) field-effect transistors (FETs), which were prepared by using conventional electron-beam lithography (EBL). The SiC NWs used in the FETs were normally in the range of 40 $\sim$ 100 nm. In addition, the current-voltage (I-V) characteristics of the SiC NW FETs were compared with the simulated results. From the 2D ATLAS simulation, the carrier mobility and the on/off ratio were estimated to be $\sim$3.06 $\times$ 10$^3$ cm$^2$/V$\cdot$s and $\sim$ 6.16, respectively. We also noticed that detailed studies, such as direct doping and modulation of the doping in SiC NWs, are required for further fabrication of high-performance SiC NW-based devices. 본 연구에서는 탄화규소 나노선 트랜지스터를 제작하여 실제 소자의 전기적인 특성을 분석하였으며 실험에서 나타난 결과를 2D ATLAS 시뮬레이션을 이용하여 비교하였다. 실험에서 제작된 탄화규소 나노선은 hot-wall 방식의 화학기상증착 방법을 이용하여 합성하였으며, 지름은 40 $\sim$ 100 nm 이다. 합성된 탄화규소 나노선을 후면 게이트 전계효과 트랜지스터 (back-gated field-effect transistors) 로 제작하였으며, 이를 2D ATLAS 시뮬레이션을 통해 탄화규소 나노선 트랜지스터 소자 동작특성을 비교 분석하였다. 2D ATLAS 시뮬레이션에서의 탄화규소 나노선의 길이와 채널의 길이, 지름은 제작된 소자와 같은 4 $\mu$m, 3 $\mu$m, 45 nm 이고, 일정한 전하 농도를 갖는다고 가정하였으며, 지름이 작아짐에 따라 나타나는 양자효과는 본 연구에서는 배제하였다. 실험결과와 시뮬레이션의 결과를 비교한 후 전하 농도가 1.5 $\times$ 10$^{17}$ cm$^{-3}$ 일 때 전류 on/off ratio ($I_{on}/I_{off}$) 와 이동도 ($\mu$) 는 각각 6.16 과 3.06 $\times$ 10$^3$ cm$^2$/V$\cdot$s 를 갖는 소자 제작이 가능함을 알 수 있었다.
M. Shaheer Akhtar,형정환,Dong-Joo Kim,양오봉,이상권,김태홍 한국물리학회 2010 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.56 No.3
We demonstrate for the first time novel perforated ZnO nanotube /TiO2 electrode-based dyesensitized solar cells (DSSCs). From the current-voltage characteristics, the open-circuit voltage VOC, short-circuit current density JSC, and the fill factor FF were determined to be ~0.84 V,~4.82 mA/cm2, and 0.60, respectively. We obtained a power conversion efficiency, η, of ~2.4%under air mass 1.5 global solar conditions. This represented an improvement of approximately 2 times as compared to ZnO nanowire/TiO2 electrode-based DSSCs. The superior photovoltaic performance and JSC value are attributed to high dye loading and high light harvesting via the high surface area of the ZnO nanotubes.
Susant Kumar Acharya,안병국,형정환,이상권 한국물리학회 2013 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.62 No.5
The piezoelectric and ferroelectric properties of x mol% Li-doped 0.94Bi<SUB>0.5</SUB>Na<SUB>0.5</SUB>TiO<SUB>3</SUB>-0.06BaTiO<SUB>3</SUB> (BNT-BT-Li<SUB>x</SUB>, x= 0, 5, 10, 15, 20) lead-free piezoelectric thin films deposited on Pt (111)/Ti/SiO<SUB>2</SUB>/Si substrates via a metal-organic solution deposition method were investigated. Our results show that Li-substituted film leads to a remarkable improvement in electrical properties compared with BNT-BT. We also found that the substitution was effective in decreasing the coercive field in the thin films. The enhanced electromechanical properties are contributed by both crystal structure evolution and improvement of the microstructure. The optimal ferroelectric properties were obtained in the film with x=10 providing the remanent polarization (<I>P<SUB>r</SUB></I>) and coercive field (<I>E<SUB>c</SUB></I>)of ~23.9 mC/cm<SUP>2</SUP> and ~124 kV/cm.
Fabrication and Characterization of P-implanted Si-nanowire Field-effect Transistors (n-SiNW FETs)
Seung-Yong Lee,Chan-Oh Jang,형정환,Dong-Joo Kim,Tae-Hong Kim,Sang-Mo Koo,김문덕,이상권 한국물리학회 2009 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.55 No.1
We report on the fabrication and the electrical characterization of n-channel silicon nanowire (SiNW) field-effect transistors (FETs), which were prepared using phosphorous (P)-ion implantation in the region of the source/drain in SiNWs at a dose of 1 × 1014 ions/cm2 and an energy of 10 keV. The current-voltage characteristics of the P-implanted SiNW FET exhibit clear n-type characteristics. We also observed critical changes in the surface morphology on the SiNWs after annealing at temperatures above 950℃.
Electrical Transport Measurements and Degradation of Graphene/n-Si Schottky Junction Diodes
박노원,이원영,이상권,김동주,김길성,형정환,홍창희,고중혁,김근수 한국물리학회 2015 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.66 No.1
We report on the electrical properties, such as the ideality factors and Schottky barrier heights,that were obtained by using current density - voltage (J − V ) and capacitance - voltage (C − V )characteristics. To fabricate circularly- and locally-contacted Au/Gr/n-Si Schottky diode, we depositedgraphene through the chemical vapor deposition (CVD) growth technique, and we employedreactive ion etching to reduce the leakage current of the Schottky diodes. The average values of thebarrier heights and the ideality factors from the J −V characteristics were determined to be 0.79± 0.01 eV and 1.80 ± 0.01, respectively. The Schottky barrier height and the doping concentrationfrom the C − V measurements were 0.85 eV and 1.76 × 1015 cm−3, respectively. Fromthe J − V characteristics, we obtained a relatively low reverse leakage current of 2.56 × 10−6mA/cm−2 at −2 V, which implies a well-defined rectifying behavior. Finally, we found that theGr/n-Si Schottky diodes that were exposed to ambient conditions for 7 days exhibited a 3.2-foldhigher sheet resistance compared with the as-fabricated Gr/n-Si diodes, implying a considerableelectrical degradation of the Gr/n-Si Schottky diodes.