• 한국결정성장학회지
• /
• 제6권3호
• /
• pp.368-376
• /
• 1996

균일한 조성과 doping 효과를 얻을 수 있는 floating zone(FZ)법으로 조화용융조성의 undoped $LiNbO_{3}$ 및 5 mol%의 MgO 또는 ZnO를 각각 첨가한 $LiNbO_{3}$ 단결정을 육성하였다. 결정성장시 최적성장조건을 실험적으로 확립하였으며, 결정내에 존재하는 domain 구조, 전위구조, slip band, 미세쌍정등의 결함구조를 조사 및 분석하였다.

• 한국정보통신학회논문지
• /
• 제13권4호
• /
• pp.747-752
• /
• 2009

본 연구에서는 FinFET에서 문턱전압이하 전류 및 단채널효과를 해석하기 위하여 필수적인 포텐셜분포를 구하기 위하여 3차원 포아송방정식을 이용하고자 한다. 특히 계산시간을 단축시키고 파라미터의 관련성을 이해하기 쉽도록 해석학적 모델을 제시하고자 한다. 이 모델의 정확성을 증명하기 위하여 3차원 수치해석학적 모델과 비교되었으며 소자의 크기파라미터에 따른 변화에 대하여 설명하였다. 특히 채널 도핑여부에 따라 FinFET의 채널 포텐셜을 구하여 향후 문턱전압이하 전류 해석 및 문턱 전압 계산에 이용할 수 있도록 모델을 개발하였다.

• 한국정보통신학회논문지
• /
• 제17권4호
• /
• pp.917-921
• /
• 2013

본 연구에서는 이중게이트 MOSFET의 전도중심에 따른 항복전압의 변화를 분석하였다. DGMOSFET에 대한 단채널효과 중 낮은 항복전압은 소자동작에 저해가 되고 있다. 항복전압분석을 위하여 포아송방정식의 분석학적 전위분포를 이용하였으며 이때 전하분포함수에 대하여 가우시안 함수를 사용함으로써 보다 실험값에 가깝게 해석하였다. 소자 파라미터인 채널길이, 채널두께, 게이트 산화막 두께 그리고 도핑농도 등에 대하여 전도중심의 변화에 대한 항복전압의 변화를 관찰하였다. 본 연구의 모델에 대한 타당성은 이미 기존에 발표된 논문에서 입증하였으며 본 연구에서는 이 모델을 이용하여 항복전압특성을 분석하였다. 분석결과 항복전압은 소자파라미터에 에 대한 전도중심의 변화에 크게 영향을 받는 것을 관찰할 수 있었다.

• Applied Microscopy
• /
• 제46권1호
• /
• pp.20-26
• /
• 2016

Our work on $Sc_2O_3-W$ matrix dispenser cathodes had been reviewed in this paper. The cathode with uniform distribution of $Sc_2O_3$ had been obtained using liquid-liquid doping method. The cathode had excellent emission property, i.e., the emission current density in pulse condition could reach over $35A/cm^2$. It was found that the cathode surface was covered by a Ba-Sc-O active substance multilayer with a thickness of about 100 nm, which was different from the monolayer and semiconducting layer in thickness. Furthermore, the observation results displayed that nanoparticles appeared at the growth steps and the surface of tungsten grains of the fully activated cathode. The calculation result indicated that the nanoparticles could cause the increase of local electric field strengths. We proposed the emission model that both the Ba-Sc-O multilayer and the nanoparticles distributing mainly on the growth steps of the W grains contributed to the emission. The future work on this cathode has been discussed.

• 한국전기전자재료학회논문지
• /
• 제12권1호
• /
• pp.18-26
• /
• 1999

In this study, the undoped amorphous layers and phosphorus doped amorphous layers are fabricated using LPCVD at 531$^{\circ}C$ with SiH$_4$ gas or at same temperature with PH$_3$ gas during deposition, respectively. The thickness of deposited amorphous layer from this experiments was 5000 ${\AA}$. In this experiments, undoped amorphous layers are deposited with SiH$_4$and Si$_2$H$\_$6/ gas in a low pressure reactor using LPCVD. These amorphous layers can be doped for poly-silicon by phosphorus ion implantation. The experiments of this study are carried out by phosphorus ion implantation with energy 40 keV into P doped and undoped amorphous silicon layers. The distribution of phosphorus profiles are measured by SIMS(Cameca 6f). Recoiling effects and two dimensional profiles are also explained by comparisions of experimental and simulated data. Finally range moments of SIMS profiles are calculated and compared with simulation results.

• 한국재료학회지
• /
• 제33권4호
• /
• pp.135-141
• /
• 2023

The volatilization of alkali ions in (K,Na)NbO₃ (KNN) ceramics was inhibited by doping them with alkaline earth metal ions. In addition, the grain growth behavior changed significantly as the sintering duration (t_s) increased. At 1,100 ℃, the volatilization of alkali ions in KNN ceramics was more suppressed when doped with alkaline earth metal ions with smaller ionic size. A Ca²⁺-doped KNN specimen with the least alkali ion volatilization exhibited a microstructure in which grain growth was completely suppressed, even under long-term sintering for t_s = 30 h. The grain growth in Sr²⁺-doped and Ba²⁺-doped KNN specimens was suppressed until t_s = 10 h. However, at t_s = 30 h, a heterogeneous microstructure with abnormal grains and small-sized matrix grains was observed. The size and number of abnormal grains and size distribution of matrix grains were considerably different between the Sr²⁺-doped and Ba²⁺-doped specimens. This microstructural diversity in KNN ceramics could be explained in terms of the crystal growth driving force required for two-dimensional nucleation, which was directly related to the number of vacancies in the material.

• 한국세라믹학회지
• /
• 제37권2호
• /
• pp.186-193
• /
• 2000

Effects of 1.0 mol% CoO addition on sintering and the electrical properties of ZnO-Bi2O3-Sb2O3(ZBS) varistor system with 3.0 mol% co-addition of Sb2O3 and Bi2O3 at various Sb/Bi ratio (0.5, 1.0, and 2.0) were investigated. Cobalt had little influence on the liquid-phase formation and the pyrochlore decomposition temepratures of ZBS, while densification was mainly dependent on Sb/Bi ratio: when Sb/Bi=0.5, excess Bi2O3 irrelevant to the formation of pyrochore(Zn2Sb3Bi3O14) forms eutectic liquid at ~75$0^{\circ}C$ which promotes densification and grain growth; with Sb/Bi=2.0, the second phase Zn7Sb2O12 formed by excess Sb2O3 irrelevant to the formation of the pyrochlore retards densification up to ~100$0^{\circ}C$. These phases caused the coarsening and uneven distribution of the second phase particles on the grain boundaries of ZnO above the pyrochlore decomposition temperature(~105$0^{\circ}C$), which led to broad size dist-ribution of ZnO; the specimen with Sb/Bi=1.0 showed homogeneous microstructure compared with the others, which enabled improved varistor characteristics. Doping of Co increased the nonlinearity and the potential barrier height of ZBS, which is thought to stem from improved sintering behavior such as homogenized microstructure due to size reduction and even distribution of the second phase and suppressed volatility of Bi2O3, as well as the improvement in the potential barrier structure via increased donor and interface electron trap densities.

• 한국정보통신학회논문지
• /
• 제18권4호
• /
• pp.885-890
• /
• 2014

비대칭 이중게이트(double gate; DG) MOSFET의 문턱전압이하 스윙의 게이트 산화막 두께에 대한 변화를 고찰하였으며 이를 위하여 포아송방정식의 해석학적 전위분포를 구하였다. 특히 포아송방정식을 풀 때 도핑분포함수에 가우시안 함수를 적용함으로써 보다 실험값에 가깝게 해석하였다. 비대칭 DGMOSFET 소자는 대칭적 구조를 갖는 DGMOSFET와 달리 4단자 소자로서 상단과 하단의 게이트 산화막 두께 및 인가전압을 달리 설정할 수 있다. 비대칭 DGMOSFET의 문턱전압이하 스윙을 상 하단 게이트 산화막 두께 변화에 따라 관찰한 결과, 게이트 산화막 두께에 따라 문턱전압이하 스윙은 크게 변화하는 것을 알 수 있었다. 특히 상 하단 게이트 산화막 두께가 증가할 때 문턱전압이하 스윙 값도 증가하였으며 상단 게이트 산화막 두께의 변화가 문턱전압이하 스윙 값에 더욱 큰 영향을 미치고 있다는 것을 알 수 있었다.

• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 2008년도 하계학술대회 논문집 Vol.9
• /
• pp.144-144
• /
• 2008

Blue light emitting diode structures consisting of the InGaN/GaN multiple quantum wells were grown by metalorganic chemical vapor deposition at different growth temperatures for the p-GaN contact layers and the influence of growth temperature on the emission and microstructural properties was investigated. The I-V and electroluminescence measurements showed that the sample with a p-GaN layer grown at $1084^{\circ}C$ had a lower electrical turn-on voltage and series resistance, andenhanced output power despite the low photoluminescence intensity. Transmission electron microscopy (TEM) revealed that the intense electro luminescence was due to the formation of a p-GaN layer with an even distribution of Mg dopants, which was confirmed by TEM image contrast and strain evaluations. These results suggest that the growth temperature should be optimized carefully to ensurethe homogeneous distribution of Mg as well as the total Mg contents in the growth of the p-type layer.

• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 2008년도 하계학술대회 논문집 Vol.9
• /
• pp.131-131
• /
• 2008

Silicon carbide (SiC) has attracted significant attention for high frequency, high temperature and high power devices due to its superior properties such as the large band gap, high breakdown electric field, high saturation velocity and high thermal conductivity. We performed Al ion implantation processes on n-type 4H-SiC substrate using a SILVACO ATHENA numerical simulator. The ion implantation model used a Monte-Carlo method. We studied the effect of channeling by Al implantation simulation in both 0 off-axis and 8 off-axis n-type 4H-SiC substrate. We have investigated the Al distribution in 4H-SiC through the variation of the implantation energies and the corresponding ratio of the doses. The implantation energies controlled 40, 60, 80, 100 and 120 keV and the implantation doses varied from $2\times10^{14}$ to $1\times10^{15}cm^{-2}$. In the simulation results, the Al ion distribution was deeper as increasing implantation energy and the doping level increased as increasing implantation doses. After the post-implantation annealing, the electrical properties of Al-implanted p-n junction diode were investigated by SILV ACO ATLAS numerical simulator.