$\gamma$-plane 사파이어 기판 위에 성장한 무분극 ${alpha}$-plane GaN 층의 전기적 비등방성 연구

김재범,김동호,황성민,김태근,Kim, Jae-Bum,Kim, Dong-Ho,Hwang, Sung-Min,Kim, Tae-Geun 대한전자공학회 2010 電子工學會論文誌-SD (Semiconductor and devices) Vol.47 No.8

본 논문에서는 무분극 GaN층에서 관찰되는 성장축의 방향성에 따른 전기적 비등방성에 대한 연구를 수행하였다. 본 연구를 위해 $\gamma$-plane 사파이어 기판 상에 유기화학기상증착법 (Metal-organic chemical vapor deposition)을 이용하여 600 nm 두께의 ${\alpha}$-plane n-type GaN층을 성장시킨 후, Ti/Al/Ni/Au (20 nm/ 150 nm/ 30 nm/ 100 nm) 오믹 전극을 증착하여 transfer length method (TLM)로 접촉저항을 측정하였다. 그 결과, ${\alpha}$-plane GaN층이 갖는 축의 방향성에 의한 접촉저항이 차이는 없는 것을 확인하였고, 면저항 측정 시에는 m-축 방향에 비해 c-축 방향에서 발생하는 면저항 값이 약 25%~75% 정도 크게 발생하는 것을 확인할 수 있었다. 이러한 전기적 특성의 비등방성은 c-축 성장방향에 대해 수직방향을 갖는 기저적층결함 (basal stacking faults)의 생성으로 인한 전자들의 거동 저하에 의한 것으로 사료된다. We report on the electrical properties of Ti/Al/Ni/Au (20 nm/ 150 nm/ 30 nm/ 100 nm) Ohmic contacts and the anisotropic conductivity of n-type ${\alpha}$-plane ([11-20]) GaN grown on $\gamma$-plane ([1-102]) sapphire substrates. The Ti/Al/Ni/Au Ohmic contacts and their sheet resistances are characterized by using the transfer length method (TLM) as a function of azimuthal angles. It is found that the specific contact resistance does not depend on the axis orientation and there are significant electrical anisotropy in ${\alpha}$-plane GaN films on $\gamma$-plane sapphire substrates, and the sheet resistance varies with azimuthal angles. The sheet resistance values in the direction parallel to m-axis [1-100] are 25% ~ 75% lower than those parallel to c-axis [0001] directions. Thus, Basal stacking faults (BSFs) are offered as a feasible source of the anisotropic mobility in defected m-axis direction because the band-edge discontinuities owing to the differential band gap structure.

ALD법으로 제조된 Al₂O₃ 박막의 물리적 특성

김재범,권덕렬,오기영,이종무,Kim, Jae-Bum,Kwon, Duk-Ryel,Oh, Ki-Young,Lee, Chong-Mu 한국재료학회 2002 한국재료학회지 Vol.12 No.6

$Al_2O_3$ is a promising gate dielectric because of its high dielectric constant, high resistivity and low leakage current. Since $OH^-$ radical in $Al_2O_3$ films deposited by ALD using TMA and $H_2O$ degrades the good properties of $Al_2O_3$, TMA and $O_3$ were used to deposite $Al_2O_3$ films and the effects of $O_3$ on the properties of the $Al_2O_3$ films were investigated. The growth rate of the $Al_2O_3$ film under the optimum condition was 0.85 $\AA$/cycle. According to the XPS analysis results the $OH^-$ concentration in the $Al_2O_3$ film deposited using $O_3$ is lower than that using $H_2O$. RBS analysis results indicate the chemical formula of the film is $Al_{2.2}O_{2.8}$. The carbon concentration in the film detected by AES is under 1 at%. SEM observation confirms that the step coverage of the $Al_2O_3$ film deposited by ALD using $O_3$ is nearly 100%.

교수재임용제도의 활성화를 위한 시사

김재범,Kim, Jae-Beom 한국대학교육협의회 1986 大學敎育 Vol.19 No.-

식도암의 수술에서 transhiatal 술식의 역할

김재범,박창권,Kim, Jae-Bum,Park, Chang-Kwon 대한기관식도과학회 2009 大韓氣管食道科學會誌 Vol.15 No.2

Background : Controversy exists whether patients with esophageal carcinoma are best managed with classical Ivor Lewis esophagectomy(ILO) as combined thoracic and abdominal approach or transhiatal esophagectomy(THO). The THO approach is known to be superior with respect to operative time, morbidity and mortality, and length of stay, especially at poor pulmonary function patient, but may represent an inferior cancer operation due to inadequate mediastinal clearance compared with ILO. Accordingly, we estimated the THO role at esophageal cancer to compare each operative approach. Material and Method : From January 2002 to December 2007, we performed a retrospective review of all esophagectomies performed at Keimyung University Dongsan Medical Center; 36 underwent THO, and 11 underwent ILO. Result : There were all men and squamous cell carcinoma but 1 woman at ILO group, 2 women at THO group. There were no significant differences between THO and ILO with age, sex, location of tumor, mean tumor length. There were significant differences at preoperative pulmonary function test(In ILO group, average FEV1 is $2.65{\pm}0.6\;L/min$ and iIn THO group, average FEV1 is $2.07{\pm}0.7\;L/min$). The amount of blood transfusion, hospital stay, leak rates and respiratory complication, hospital mortality rate were not significantly different. Conclusion : There was no significant difference in the post-operative complication, hospital mortality rate, long-term survival of patients of both operative method. THO method had lower mobidity and mortality at poor pulmonary function patient than ILO method. Hence, THO is a valid alternative to ILO for patients with poor general condition or expected post-operative respiratory complication.

우리나라 도서지역의 토지피복과 변화패턴 분석

김재범,이보라,이호상,조낭현,박찬우,이광수,Kim, Jaebeom,Lee, Bora,Lee, Ho-Sang,Cho, Nanghyun,Park, Chanwoo,Lee, Kwang-Soo 한국농림기상학회 2022 한국농림기상학회지 Vol.24 No.3

In this study, the island's land-use and land-cover change (LULCC) is analyzed in South Korea using remotely sensed land cover data(Globeland 30) acquired from 2000 to 2020 to meet the requirement of providing practical information for forest management. Analysis of LULCC between the 2000 and 2020 images revealed that changes to agricultural land were the most common type of change (7.6% of pixels), followed by changes to the forest (5.7%). The islands forests maintain 157,246 ha (42.2% of the total island area). Land cover types that changed to the forest from grasslands were 262 islands, while reverse cases have occurred on 421 islands. These 683 islands have a possibility of transition and disturbance. The artificial land class was newly calculated in 22 islands. The forests, which account for 42.2% of the 22 island area, turned into grassland, and 27.8% of agricultural land and grassland turned into forests. The development of artificial land often affects developed areas and surrounding areas, resulting in deforestation, management of agriculture, and landscaping. This study can provide insights concerning the fundamental data for assessing ecological functions and constructing forest management plans in islands ecosystems.

표준·시험인증 기술동향 - Mobile POS 관련 시장 및 기술 동향

김재범,Kim, Jae-Beom 한국정보통신기술협회 2016 TTA저널 Vol.163 No.-

저전압구동 ZnS:Mn EL device의 제작 및 전기 광학적 특성조사

김재범,김도형,장경동,배종규,남경엽,이상윤,조경제,장훈식,이현정,이동욱,Kim, Jae-Beom,Kim, Do-Hyeong,Jang, Gyeong-Dong,Bae, Jong-Gyu,Nam, Gyeong-Yeop,Lee, Sang-Yun,Jo, Gyeong-Je,Jang, Hun-Sik,Lee, Hyeon-Jeong,Lee, Dong-Uk 한국재료학회 2000 한국재료학회지 Vol.10 No.4

ZnS:Mn TFEL device를 전자선 진공증착법으로 제작하여 전기광학적 특성에 관하여 조사하였다. $Ta_2O_5$ 박막의 산소 결핍에 따른 정전용량을 측정하기 위하여 산소분위기에서 열처리에 따른 AES(Auger electron spectroscopy)와 C-F를 측정하였다. 제작한 EL 소자의 전기장 발광 파장은 550~650nm 였으며 이것은 $Mn^{2+}$ 이온의 $3d^5$ 여기준위인 $^4T_1(^4G)$ 에서 $3d^5$ 기저준위인 $^6A_1(^S)$로의 내각전자전이 피크이다. 열처리를 수행하지 않은 $Ta_2O^5$를 절연층으로 사용한 EL 소자의 발광시작전압은 24~28V이고 색도 좌표값 X=0.5151, Y=0.4202인 황등색 발광을 하였다. $Ta_2O_5$를 절연층으로 사용한 소자가 저전압에서 구동이 가능하므로 EL 소자의 실용화가 기대된다. ZnS:Mn TFEL devices were fabricated by electron-beam evaporation method and then the electro-optical properties were investigated. To investigate the capacitance which was due to oxygen vacancy at the $Ta_2O_5$ thin film, AES(Auger Electron Spectroscopy) and C-F(capacitance-frequency) measurements were used. It was found that the capacitance was decreased by annealing the $Ta_2O_5$ film in oxygen ambience. From EL emission measurement, we observed the EL emission spectrum which had the peak range from 550nm and 650nm. This emission is associated with the transition from $^4T_1(^4G)$ first excited state to $^6A_1(^6S)$ ground state in the $3d^5$ energy level configuration of $Mn^{2+}$ occurs. The threshold voltage of EL device with $Ta_2O_5$ insulator layer was found to be 24V~28V. The CIE color coordinates of these emission are X=0.5151, Y=0.4202 which is yellowish orange emitting. The EL device using $Ta_2O_5$ insulator layer can be driven with a low voltage which is beneficial to the practical application.

Special Report - 핀테크 규제 및 시험인증

김재범,Kim, Jae-Beom 한국정보통신기술협회 2017 TTA저널 Vol.172 No.-

Tracheal and esophageal injury by fish bone

김재범,박창권,Kim, Jae-Bum,Park, Chang-Kwon The Korean Bronchoesophagological Society 2008 大韓氣管食道科學會誌 Vol.14 No.1

Tracheal injury associated with esophageal injury due to fish bone is very rare. Also, treatment of mediastinitis due to esophageal perforation when it is diagnosed late remains controversial. We report the case that we have successfully experienced treatment of mediastinitis due to tracheal and esophageal injury by fish bone.

중간 기관지 내 이물의 수술적 치료

김재범,박창권,Kim, Jae-Bum,Park, Chang-Kwon 대한기관식도과학회 2010 大韓氣管食道科學會誌 Vol.16 No.1

Occult bronchial foreign body is that long-standing foreign body lodge in bronchial tree. Occult bronchial foreign bodies arc rare in adults, whereas tracheobronchial aspiration of foreign bodies occurs commonly in children. A 65-year-old man with chronic cough, sputum production, and fever was transferred for treatment of right middle and lower lobc collapse and obstructive pneumonitis as evidenced by imaging studies. The patient was treated with right middle-lower bilobectomy because fiberoptic bronchoscopic removal of the foreign body failed. We report this case with review of literatures.