완전도체 스트립 회절격자에 의한 E-분극산란 ( E-Polarized Scattering by a Perfectly Conducting Strip Grating )

윤의중,이재기,김남일 대한전자공학회 1993 대한전자공학회 세미나 Vol.1993 No.-

High-energy Electron Beam Irradiation of Al-doped ZnO Thin Films Deposited at Room Temperature

윤의중,정진우,황종하,이병철,정명희 한국물리학회 2011 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.58 No.31

In this research, we demonstrated the effects of high-energy electron beam irradiation (HEEBI) on the optical and structural properties of Al-doped ZnO (AZO) films grown on transparent corning glass substrates at room temperature (RT) by using a radio-frequency magnetron sputtering technique. The AZO thin films were treated with HEEBI in air at RT at an electron beam energy of 0.8 MeV and doses of 1 × 10^(14) - 1 × 10^(16) electrons/cm^2. The photoluminescence (PL) measurements revealed that the dominant peak at 2.77 eV was a blue emission originating from donor-like defects, oxygen vacancies (V_o), suggesting that the n-type conductivity was preserved in HEEBI-treated films. On the basis of PL, X-ray diffraction (XRD), and X-ray photoelectron spectroscopy results, we suggest that the density of V_o donor defects is decreased due to in-diffusion of oxygen from the ambient into the films after HEEBI treatment at low doses up to 10^(15) electrons/cm^2 while the opposite phenomenon can occur with further increase in the dose. We also found from the XRD analysis that the worse crystallinity with a smaller grain size was observed in HEEBI-treated AZO films at a higher dose, corresponding to a higher oxygen fraction in the films. We believe that our results will contribute to developing high-quality AZO-based materials and devices for space applications.

전자파 환경과 EMI/EMC에 관한 연구

윤의중 京畿專門大學 2000 京畿專門大學 論文集 Vol.- No.28

In this paper, it has been carried out to solve the Electromagnetic Environment and EMI/EMC(Electromagnetic Interference/Electromagnetic Compatibility) problems in high performance of electronic test and measurement products. The electric and magnetic fields radiated by lighting discharges are significantly changeable in amplitude and time, one of the topics concerning electromagnetic compatibility of modern electronic system is the efficient and economic protection against transient voltages caused by not only by direct but also by nearly lighting strokes. The electromagnetic and magnetic fields waveforms associated with lighting return strokes are significantly different with those of intracloud discharges.

Effect of Hydrogen Peroxide on the Stability of Undoped p-Type ZnO Prepared by Magnetron Sputtering

윤의중,Hyoung G. Nam,Hyeong-Sik Park,이규항,Kyung-Hwan Cha,조남인 한국물리학회 2008 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.52 No.3

In this study, we demonstrate that ZnO deposited onto SiO2 substrates by magnetron sputtering produces p-type ZnO at higher O2 pressure and n-type ZnO at lower O2 pressure. We also report the effect of hydrogen peroxide (H2O2) on the stability of undoped ZnO thin lms. The lms were immersed in 30 % H2O2 for 1 min at 30℃ and annealed in O2 at 450℃. The surface morphologies and structures of the samples were characterized by scanning electron microscopy (SEM) and X- ray diffaction (XRD), respectively. The optical properties were evaluated by PL measurements at room temperature. The carrier concentration, mobility, and conductivity were measured by using a Hall effect measurement system. The Hall measurement results for the ZnO flms untreated with H2O2 but annealed in O2 indicate that oxygen fractions greater than ~0.5 produce undoped p-type ZnO flms whereas oxygen fractions less than 0.5 produce undoped n-type ZnO flms. This is attributed to the fact that the oxygen vacancies (Vo) decrease and the oxygen interstitials (Oi) or zinc vacancies (VZn) increase with increasing oxygen atoms incorporated into ZnO flms during deposition and O2 post-annealing. From the XRD and the resistivity measurements, the changes induced by O2 annealing were observed to be quenched by H2O2. p-type ZnO flms deposited at an oxygen fraction of 0.67 showed a dominant UV peak at 3.194 eV related to a neutral acceptor bound exciton and Oi or VZn whereas n-type ZnO flms deposited at an oxygen fraction of 0.2 showed a dominant UV peak at 3.261 eV related to a neutral donor bound exciton and zinc interstitials (Zni) defects. We concluded from the experimental results that the active oxygen species decomposed from H2O2 can combine with Zni and fll Vo defects; thus, H2O2 improves the stability of undoped p-type ZnO thin lms by reducing Zni and Vo defects and/or passivating grain boundaries.

Fourier-Galerkin 모멘트 법을 이용한 誘電體 平面 위의 導體格子構造에서의 E-分極 電磁波散亂 解析

윤의중 京畿專門大學 1996 京畿專門大學 論文集 Vol.- No.24

Characterization of Undoped ZnO Films Post-Annealed by Using Helium Gas

윤의중,Hyeong-Sik Park,Kyu H. Lee,Hyoung G. Nam 한국물리학회 2009 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.54 No.2

In this study, we used helium gas for the first time for annealing undoped ZnO films at different temperatures in the range of 500 ~800℃ and we report their structural, optical and electrical properties. All measurements were carried out at room temperature. The undoped ZnO samples exhibited a (002) preferential orientation with the c-axis perpendicular to the substrate, suggesting that samples of high quality were prepared. The PL spectra of the ZnO samples revealed a strong near-band-edge ultraviolet (UV) emission peak at 3.26 eV, a strong red emission peak at 1.91 eV and a weak green emission peak at 2.36 eV, which were attributed to a free electron-acceptor transition, a zinc interstitial and a single ionized oxygen vacancy, respectively. All peak strengths in the PL spectra increased with increasing post-annealing temperature. We also confirmed from PL and Hall measurements that all samples revealed n-type conductivity. With increasing post-annealing temperature, the electron carrier concentration and the strength of UV emission peak increased, suggesting that they are related to each other. In this study, we used helium gas for the first time for annealing undoped ZnO films at different temperatures in the range of 500 ~800℃ and we report their structural, optical and electrical properties. All measurements were carried out at room temperature. The undoped ZnO samples exhibited a (002) preferential orientation with the c-axis perpendicular to the substrate, suggesting that samples of high quality were prepared. The PL spectra of the ZnO samples revealed a strong near-band-edge ultraviolet (UV) emission peak at 3.26 eV, a strong red emission peak at 1.91 eV and a weak green emission peak at 2.36 eV, which were attributed to a free electron-acceptor transition, a zinc interstitial and a single ionized oxygen vacancy, respectively. All peak strengths in the PL spectra increased with increasing post-annealing temperature. We also confirmed from PL and Hall measurements that all samples revealed n-type conductivity. With increasing post-annealing temperature, the electron carrier concentration and the strength of UV emission peak increased, suggesting that they are related to each other.

Development of Transparent Thin Film Transistors on PES Polymer Substrates

윤의중,정진우,고경남,송영욱,Hyoung G. Nam,조남인 한국물리학회 2010 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.57 No.41

In this study, we demonstrate ZnO-based transparent thin film transistors (TTFT’s) implemented on polyethersulfone (PES) polymer substrates. For the developed TTFT’s, radio-frequencymagnetron sputter techniques were used to deposit Al-doped ZnO (AZO) at zero oxygen partial pressures for the source, the drain, and the gate-contact electrodes, undoped ZnO at low oxygen partial pressures for the active p-type layer, and SiO2 for the gate dielectric. The TTFT’s were processed at room temperature (RT), except for a 100 ℃ sputtering step to deposit the AZO source,drain, and gate-contact electrodes. The devices have bottom-gate structures with top contacts,are optically transparent, and operate in an enhancement mode with a threshold voltage of +13V, a mobility of 0.1 cm2/Vs, an on-off ratio of about 0.5 × 103 and, a sub-threshold slope of 4.1V/decade.

FGMM을 이용한 2중 유전체층 사이의 완전도체띠 격자구조에 의한 E-분극 전자파 산란 해석

윤의중 한국인터넷방송통신학회 2020 한국인터넷방송통신학회 논문지 Vol.20 No.1

In this paper, E-polarized electromagnetic scattering problems by a conductive strip grating between a double dielectric layer are analyzed by applying the FGMM(Fourier-Galerkin moment method) known as a numerical method of electromagnetic fileld. The boundary conditions are applied to obtain the unknown field coefficients, and the conductive boundary condition is applied to analysis of the conductive strip. The numerical results for the normalized reflected and transmitted power are analyzed by according as the width and spacing of conductive strip, the relative permittivity and thickness of the double dielectric layers, and incident angles. Generally, as the value of the dielectric constant of the double dielectric layer increases, the reflected power increases and the transmitted power decreases, respectively. As the dielectric constant of the double dielectric layer increases, the current density induced in the strip center increases. The numerical results for the presented structure of this paper are shown in good agreement compared to those of the existing papers. 본 논문에서는 2중 유전체층 사이의 완전도체띠 격자구조에 의한 E-분극 전자파 산란 문제는 전자파 수치해석방법으로 알려진 FGMM(Fourier-Galerkin moment method)를 이용하여 해석하였다. 경계조건들은 미지의 계수를구하기 위하여 이용하였고, 도체띠의 해석을 위해 완전도체 경계조건을 적용하였다. 도체띠의 폭과 주기, 2중 유전층사이의 비유전율과 두께 및 입사각에 대해 정규화된 반사전력과 투과전력을 계산하였다. 전반적으로 2중 유전체 층의비유전율이 증가할수록 반사전력은 증가하였으며, 상대적으로 투과전력은 감소하였다. 2중 유전체 층의 비유전율이 증가할수록 도체띠에 유도되는 전류밀도는 스트립 중앙에서 증가하였다. 본 논문의 제안된 구조에 대한 수치결과들은 기존논문의 수치해석 결과들과 비교하여 매우 잘 일치하였다.

E-波의 入射에 의한 接地誘電體 平面을 가지는 導體띠 格子構造에서의 電磁波散亂에 關한 硏究

윤의중 京畿專門大學 1998 京畿專門大學 論文集 Vol.- No.26

In this paper, Electromagnetic scattering problem by a perfectly conducting strip grating with a grounded dielectric plane by incidence of a electric wave is analyzed by applying the PMM (Point Matching Method) known as a simple procedure. The scattered electromagnetic fields are expanded in a series of Floquet mode functions. The boundary conditions are applied to obtain the unknown field coefficients and the conducting boundary condition is used for the relationship between the tangential electric field and the electric current density on the strip. When the incident angle is normal incidence, the minimum value of the geometrically normalized reflected power according as relative permittivity is increased, it should be noted that the value of the strip width gets moved toward high value. Then most energy by a normal incident wave is scattered in direction of the other angles except normal incident angle.

誘電體 平面 위의 導體 格子構造에 의한 H-分極 電磁波散亂에 關한 硏究

윤의중 京畿專門大學 1997 京畿專門大學 論文集 Vol.- No.25