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DLC(Diamond Like Carbon) Films의 열전도도
채희백,이태기 순천향대학교 기초과학연구소 1997 순천향자연과학연구 논문집 Vol.3 No.1
DLC(Diamond Like Carbon) films were deposited by RF-PACVD(Radio Frequency - Plasma Assited Vapor Deposited) method. Films were deposited by varying negative self bias voltage(bias voltage was 100V, 500V) and the substrate was silicon wafer. Thermal conductivity of DLC film was measured by 3ω-method(quasi steady state method) in a temperature range 77K∼300K. Thermal conductivity of the film which was made at high bias voltage is higher than the film which was made at low bias voltage.
채희백,김종철 순천향대학교 기초과학연구소 1997 순천향자연과학연구 논문집 Vol.3 No.1
FIbrous glass board is widely used for the heat-insulation material. Thermal conductivity of these material is low. NIST prepared the cirtified reference material which is used for the comparison and verification of the apparatus for thermal conductivity measurements Guarded hot plate method is used to measure thermal conductivity and the results are compared with NIST data. Heat conduction path has three modes, such as through the fiber glass itself, air between the fiber and by radiation. The apparent thermal conductivity of fiber glass board 1450b is 3.5~4.2x10-2 W/m K in a temperature range from ambient to 345K. It's in agreement with NIST data within ±1.5%.
채희백,이수빈,홍진수,김승우 순천향대학교 기초과학연구소 1997 순천향자연과학연구 논문집 Vol.3 No.2
Nd-Yag pulsed laser(210mJ, 6ns) was focused on polymer to make craters in an atmosphere. The size of the crater has a trend to follow the ideal estimation. Laser-firing near the focal point in air could be an energy dissipation of laser and a possible cause of the crater size reduction. Multiple plasma image and normal eruption of the plasma was also studied with photographs.
채희백 순천향대학교 기초과학연구소 1995 순천향자연과학연구 논문집 Vol.1 No.1
We measured high temperature thermophysical properties of POCO-AXM-5Q1 graphite which has been used as a reference standard material from NIST(National Institute of Standards and Technology). Thermal diffusivity an specific heat were measured in a temperature range 300∼1400K with laser flash method. Specific heat is modeled by the Debye phonon model. Thermal conductivity can be calculated by the measured specific heat and the measured thermal diffusivity. Electrical conduction and thermal conduction are correlated as the Wiedemann-Frantz law which is modeled with the free electron gas. High temeprature thermal conduction is governed by the phonon-phonon scattering as U-process or N-process. The combined model is fitted to the data and analysed.
채희백,정영석,이태기 순천향대학교 기초과학연구소 1997 순천향자연과학연구 논문집 Vol.3 No.2
Nano-sized SiC particles of 1, 10, 20 and 30 vol% were dispersed in a-Si₃N₄ matrix and hot-pressed under the condition of 30 MPa of N₂ at 1850℃. Thermal conductivity of Si₃N₄-SiC nanocomposite was measured between 300 K and 400 K. Si₃N₄-20 vol% SiC showed the lowest thermal conductivity. In growth Si₃N₄, SiC-nano particle could be a nucleation site and dispersion is maximized in the Si₃N₄-matrix when the vol% is 20. More than 20 vol% SiC, SiC particles are located on the Si₃N₄ boundaries. Thus, phonons are scattered well in Si₃N₄-20 vol% SiC with the dispersed SiC and thermal resistance(conductivity) is high(low). Similar behavior was reported in the electricl resistivity and fracture toughness.
DCJTB를 도핑시킨 단층 Alq₃소자에서 Two-color filter를 사용한 발광영역의 결정
채우리,채희백,최성진 순천향대학교 기초과학연구소 2011 순천향자연과학연구 논문집 Vol.17 No.2
A doping layer of thickness 2 nm of DCJTB(guest) was dopoed 1 % and varied its location 5nm each from the anode to the cathode in a single layer Alq(60 nm, host) OLED in order to investigate the region of charge recombination and light emission. Major emission peak was located 20 nm from the anode and the emission region was shown to be spread through the whole layer of Alq. We also investigate a method to determine the recombination zone with two-color filter from TEL
박세일,채희백 순천향대학교 기초과학연구소 1996 순천향자연과학연구 논문집 Vol.2 No.1
화학증착법으로 합성한 다이아몬드 필름의 비열을 80 - 400 k사이에서 AC Calorimetry를 사용하여 측정하였다. 합성할 때 반응로내의 메탄가스의 농도를 7.5%와 10%로 하였다. 다이아몬드필름내에 주상구조의 낱알경계가 관찰되었다. 열전도도 측정과 광학현미경관찰을 한 결과 point defects, extended defect, dislocation 및 void 등의 불순물이 필름내 존재함이 확인되었다. 이들 defects들은 열에너지 운반자 -포논과 충돌을 일으키는 scattering center가 되며 결정도를 떨어뜨리는 원인이된다. 또한 이들은 결정의 경도를 떨어뜨리게되며 결과적으로 비열을 증가시킨다. 측정된 비열데이터를 디바이모델로 해석하여 디바이온도를 구하였다.
홍진수,채희백,안성기,박해윤 순천향대학교 기초과학연구소 2001 순천향자연과학연구 논문집 Vol.7 No.2
유기발광 응용에 성공적으로 사용되어 새로운 물질을 개발할 때 기준으로 사용되는 Alq_3와 TPD필름을 기존의 증착법(열증착법과 스핀코터 기술)을 대체할 수 있는 고출력펄스레이저로 합성하였다. 펠릿 타겟은Q-스위칭 Nd:YAG 레이저의 532 nm와 355 nm를 사용하여 2&10^-6 Torr압력 하에서 용발시킨다. 슬라이드 유리 위에 증착된 필름은 유기발광 디바이스에 사용될 가능성이 있는지 알기 위해 다음과 같은 조사를 하였다: PL,AFM, 흡수 스펙트라, XRD. 355 nm 레이저로 유기필름을 증착하면 532 nm 경우의 필름보다 결합이 적고, 특히 열증착 필름보다 스트레스를 덜 받는다는 사실을 알 수 있다. 또한 타겟의 구조가 Alq_3 다를지라도 레이저 증착법으로 합성된 Alq_3 필름은 열증착과 동일한 구조를 갖는다는 사실을 알 수 있다. 어느 레이저를 사용하건 증착된 필름은 결정구조를 확인할 수 없을 정도로 비정질을 이룬다는 사실을 알 수 있다.
DCJTB를 도핑시킨 NPB/Alq₃ 복층소자에서 엑시톤 확산
송석태,채희백,한찬수 순천향대학교 기초과학연구소 2011 순천향자연과학연구 논문집 Vol.17 No.2
Red dye DCJTB was doped 2% with thickness 1nm in NPB(40nm)/Alq₃(60nm) bilayer in order to investigate the diffusion of exciton. The location of the dopant layer was varied from the junction of NPB/Alq by 5nm. The emission zone was distributed narrow in Alq side near the junction. The diffusion length of exciton was 15nm ± 5nm which was confirmed from the measurements of Rubrene doped NPB(40nm)/Alq₃(60nm) bilayer system.
정재훈,채희백,한용진,이수빈,홍진수 순천향대학교 기초과학연구소 1998 순천향자연과학연구 논문집 Vol.4 No.2
A faraday cup has been used to obtain informations of various carbon ions in plasma generated during PLD(Pulsed laser deposition). We propose an analytical expression for the velocity distributions of carbon ions ejected in laser ablation. Under the applied voltage the Maxwell-Boltzmann distribution on a stream velocity was adopted to describe the measured velocity distributions. The kinetic ion energies are calculated to be in the range of 605.9eV to 30.7eV. The number are inverse proportional to their kinetic energies : ?? in the oder named.