• 한국재료학회지
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• 제9권2호
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• pp.168-172
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• 1999

보른이 고농도 도핑된 $\textrm{p}^{+}$-Si 영역상에서 비저항이 낮고 열적 안정성이 우수한 Co/Ti 이중막 실리사이드의 형성을 연구하였다. 본 연구에서는 Co/Ti 이중막 실리사이드는 청결한 $\textrm{p}^{+}$-Si 기판상에 Co(150${\AA}$)/Ti(50${\AA}$) 박막을 E-beam 기술로 진공증착하고 질소분위기($\textrm{10}^{-1}$atm)에서 2단계 RTA 공정(1차열처리:$650^{\circ}C$/20sec, 2차열처리:$800^{\circ}C$/20sec)을 수행하여 제작된다. 실험에서 얻어진 Co/Ti 이중막 실리사이드는 약 500${\AA}$의 균일한 두께를 갖고 18$\mu\Omega$-cm의 낮은 비저항 특성을 나타내었으며, $1000^{\circ}C$에 이르기까지 장시간 후속 열처리를 실시하여도 면저항 변화나 열응집 현상이 발생되지 않았다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2001년도 추계학술대회 논문집 Vol.14 No.1
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• pp.197-200
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• 2001

In this letter, we report on the investigation of Ni/Si/Ni Ohmic contacts to n-type 4H-SiC. Ohmic contacts have been formed by a vacuum annealing and $N_2$ gas ambient annealing method at $950^{\circ}C$ for 10 min. The specific contact resistivity ( $\rho_{c}$ ), sheet resistance($R_s$), contact resistance($R_c$), transfer length($L_T$) were calculated from resistance($R_T$) versus contact spacing(d) measurements obtained from 10 TLM(transmission line method) structures. The resulting average values of vacuum annealing sample were $\rho_{c}=3.8{\times}10^{-5}\Omega cm^{3}$, $R_{c}=4.9{\Omega}$, $R_{T}=9.8{\Omega}$ and $L_{T}=15.5{\mu}m$, resulting average values of another sample were $\rho_{c}=2.29{\times}10^{-4}\Omega cm^{3}$, $R_{c}=12.9{\Omega}$ and $R_{T}=25.8{\Omega}$. The physical properties of contacts were examined using X-Ray Diffraction and Auger analysis, there was a uniform intermixing of the Si and Ni, migration of Ni into the SiC.

• 한국진공학회지
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• 제9권4호
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• pp.341-345
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• 2000

p형 Si (100)기판 위에 reactive DC magnetron sputtering으로 증착한 $ZrO_2$박막에 대하여 증착 조건과 열처리 조건에 따른 미세구조의 변화 및 전기적 특성 변화를 관찰하였다. 증착 및 열처리 온도가 증가하고 power 증가할수록 $ZrO_2$의 굴절율은 증가되어 이상적인 2.0~2.2에 근접하였다. 상온에서 증착된 $ZrO_2$ 박막은 비정질이며 $300^{\circ}C$에서 증착한 경우 $ZrO_2$박막은 다결정이었다. 산소 분위기에서 열처리를 수행한 박막의 RMS 값은 증착직후보다 높아지고 계면 산화막은 산소의 확산에 의해 두께가 증가하였다. A1/$ZrO_2$/p-type Si(100)의 C-V과 I-V 특성을 관찰하였고, 그 결과 산소분위기에서 열처리하는 경우 계면 산화막의 두께증가로 Cmax 및 누설전류가 감소함을 알 수 있었다.

• 한국재료학회:학술대회논문집
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• 한국재료학회 2009년도 춘계학술발표대회
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• pp.29.1-29.1
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• 2009

Fabrication of good quality P-type GaN remained as a challenge for many years which hindered the III-V nitrides from yielding visible light emitting devices. Firstly Amano et al succeeded in obtaining P-type GaN films using Mg doping and post Low Energy Electron Beam Irradiation (LEEBI) treatment. However only few region of the P-GaN was activated by LEEBI treatment. Later Nakamura et al succeeded in producing good quality P-GaN by thermal annealing method in which the as deposited P-GaN samples were annealed in N2 ambient at temperatures above $600^{\circ}C$. The carrier concentration of N type and P-type GaN differs by one order which have a major effect in AlGaN based deep UV-LED fabrication. So increasing the P-type GaN concentration becomes necessary. In this study we have proposed a novel method of activating P-type GaN by electrochemical potentiostatic method. Hydrogen bond in the Mg-H complexes of the P-type GaN is removed by electrochemical reaction using KOH solution as an electrolyte solution. Full structure LED sample grown by MOCVD serves as anode and platinum electrode serves as cathode. Experiments are performed by varying KOH concentration, process time and applied voltage. Secondary Ion Mass Spectroscopy (SIMS) analysis is performed to determine the hydrogen concentration in the P-GaN sample activated by annealing and electrochemical method. Results suggest that the hydrogen concentration is lesser in P-GaN sample activated by electrochemical method than conventional annealing method. The output power of the LED is also enhanced for full structure samples with electrochemical activated P-GaN. Thus we propose an efficient method for P-GaN activation by electrochemical reaction. 30% improvement in light output is obtained by electrochemical activation method.

• 한국진공학회지
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• 제20권2호
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• pp.127-134
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• 2011

본 연구에서는 고분해능 X선 회절법을 이용해 Ni/Ag 반사막 p형 오믹 전극의 Ag 집괴에 따른 전극의 구조 분석을 수행하였다. 대기 분위기에서 오믹 전극을 고온 열처리할 경우, 열처리 시간이 증가할수록 Ag의 집괴가 진행되어 24시간 열처리 후, 전류-전압 곡선은 쇼트키 특성을 나타내었고, 또한 460 nm 파장에서 21%의 낮은 반사도를 나타내었다. X선 회절 결과로부터 Ag의 집괴가 진행될수록, Ag 박막의 내부 변형율을 감소되는 방향으로 Ag 원자의 확산이 진행되어, Ag (111) 결정면의 면간 거리가 bulk Ag와 거의 동일하게 나타났다. 이러한 반사막 오믹 전극의 구조 분석은 고출력 고효율 수직형 LED에 적합한 열적 안정성이 우수한 오믹 전극의 개발에 매우 중요함을 알 수 있다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2001년도 추계학술대회 논문집
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• pp.197-200
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• 2001

In this letter, we report on the investigation of Ni/Si/Ni Ohmic contacts to n-type 4H-SiC. Ohmic contacts have been formed by a vacuum annealing and N$_2$ gas ambient annealing method at 950$^{\circ}C$ for 10 min. The specific contact resistivity($\rho$$\sub$c/), sheet resistance(R$\sub$S/), contact resistance(R$\sub$S/), transfer length(LT) were calculated from resistance(R$\sub$T/) versus contact spacing(d) measurements obtained from 10 TLM(transmission line method) structures. The resulting average values of vacuum annealing sample were $\rho$$\sub$c/=3.8x10$\^$-5/ Ω$\textrm{cm}^2$ , R$\sub$c/=4.9Ω, R$\sub$T/=9.8Ω and L$\sub$T/=15.5$\mu\textrm{m}$, resulting average values of another sample were $\rho$$\sub$c/=2.29x10$\^$-4/ Ω$\textrm{cm}^2$ , R$\sub$c/=12.9Ω, R$\sub$T/=25.8Ω. The Physical properties of contacts were examined using X-Ray Diffraction and Auger analysis, there was a uniform intermixing of the Si and Ni, migration of Ni into the SiC.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2003년도 추계학술대회 논문집 Vol.16
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• pp.167-171
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• 2003

We report the material and electrical properties of $CoSi_2$ and $NiSi_2$contacts to n-type 4H-SiC depending on the post-annealing and the metal covering conditions. The Ni and Co silicides are deposited by RF sputtering with Ni/Si/Ni and Co/Si/Co films separately deposited on 4H-SiC substrates. The deposited films are annealed at $800\;^{\circ}C$ in $Ar:H_2$ (9:1) gas ambient. Results of the specific surface resistivity measurements show that the resistivity of the Co-based metal contact was the one order lower than that of the Ni-based contact. The specific contact resistance was measured by a transmission line technique, and the specific contact resistivity of $1.5{\times}10^{-6}\;{\Omega}\;cm^2$ is obtained for Co/Si/Co metal structures after a two-step annealing; at $550\;^{\circ}C$ for 10 min and $800\;^{\circ}C$ for 3min. The physical properties of the contacts were examined by using XRD and AES, and the results indicate that the Co-based metal contacts have better structural stability of silicide phases formed after the high temperature annealing.

• 한국재료학회지
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• 제24권9호
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• pp.443-450
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• 2014

Amorphous (a-Si) films were epitaxially crystallized on a very thin large-grained poly-Si seed layer by a silicide-enhanced rapid thermal annealing (SERTA) process. The poly-Si seed layer contained a small amount of nickel silicide which can enhance crystallization of the upper layer of the a-Si film at lower temperature. A 5-nm thick poly-Si seed layer was then prepared by the crystallization of an a-Si film using the vapor-induced crystallization process in a $NiCl_2$ environment. After removing surface oxide on the seed layer, a 45-nm thick a-Si film was deposited on the poly-Si seed layer by hot-wire chemical vapor deposition at $200^{\circ}C$. The epitaxial crystallization of the top a-Si layer was performed by the rapid thermal annealing (RTA) process at $730^{\circ}C$ for 5 min in Ar as an ambient atmosphere. Considering the needle-like grains as well as the crystallization temperature of the top layer as produced by the SERTA process, it was thought that the top a-Si layer was epitaxially crystallized with the help of $NiSi_2$ precipitates that originated from the poly-Si seed layer. The crystallinity of the SERTA processed poly-Si thin films was better than the other crystallization process, due to the high-temperature RTA process. The Ni concentration in the poly-Si film fabricated by the SERTA process was reduced to $1{\times}10^{18}cm^{-3}$. The maximum field-effect mobility and substrate swing of the p-channel poly-Si thin-film transistors (TFTs) using the poly-Si film prepared by the SERTA process were $85cm^2/V{\cdot}s$ and 1.23 V/decade at $V_{ds}=-3V$, respectively. The off current was little increased under reverse bias from $1.0{\times}10^{-11}$ A. Our results showed that the SERTA process is a promising technology for high quality poly-Si film, which enables the fabrication of high mobility TFTs. In addition, it is expected that poly-Si TFTs with low leakage current can be fabricated with more precise experiments.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2009년도 하계학술대회 논문집
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• pp.327-327
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• 2009

ZnO with a large band gap (~3.37 eV) and exciton binding energy (~60 meV), is suitable for optoelectronic applications such as ultraviolet (UV) light emitting diodes (LEDs) and detectors. However, the ZnO-based p-n homojunction is not readily available because it is difficult to fabricate reproducible p-type ZnO with high hall concentration and mobility. In order to solve this problem, there have been numerous attempts to develop p-n heterojunction LEDs with ZnO as the n-type layer. The n-ZnO/p-GaN heterostructure is a good candidate for ZnO-based heterojunction LEDs because of their similar physical properties and the reproducible availability of p-type GaN. Especially, the reduced lattice mismatch (~1.8 %) and similar crystal structure result in the advantage of acquiring high performance LED devices. In particular, a number of ZnO films show UV band-edge emission with visible deep-level emission, which is originated from point defects such as oxygen vacancy, oxygen interstitial, zinc interstitial[1]. Thus, defect-related peak positions can be controlled by variation of growth or annealing conditions. In this work, the undoped ZnO film was grown on the p-GaN:Mg film using RF magnetron sputtering method. The undoped ZnO/p-GaN:Mg heterojunctions were annealed in a horizontal tube furnace. The annealing process was performed at $800^{\circ}C$ during 30 to 90 min in air ambient to observe the variation of the defect states in the ZnO film. Photoluminescence measurements were performed in order to confirm the deep-level position of the ZnO film. As a result, the deep-level emission showed orange-red color in the as-deposited film, while the defect-related peak positions of annealed films were shifted to greenish side as increasing annealing time. Furthermore, the electrical resistivity of the ZnO film was decreased after annealing process. The I-V characteristic of the LEDs showed nonlinear and rectifying behavior. The room-temperature electroluminescence (EL) was observed under forward bias. The EL showed a weak white and strong yellowish emission colors (~575 nm) in the undoped ZnO/p-GaN:Mg heterojunctions before and after annealing process, respectively.

• 대한전자공학회논문지SD
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• 제46권2호
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• pp.9-14
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• 2009

본 연구에서는 sapphire 기판위에 P (phosphorus) 도핑된 ZnO 박막을 제작한 후, 산소 분위기에서 후열 처리 온도가 박막의 전기적 및 광학적 특성에 미치는 영향에 대해서 조사하였다. XRD 측정 결과, 후열 처리 온도에 무관하게 모든 박막이 c축 배향성을 나타내었다. Hall 측정 결과, $850^{\circ}C$에서 후열 처리한 박막에서만 p형 전도 특성이 관찰되었다. 이때의 홀 캐리어 농도와 홀 이동도는 각각 $1.18{\times}1016cm^{-3}$과 $0.96cm^2/Vs$의 값을 나타내었다. 저온 PL 측정 결과, $850^{\circ}C$에서 후열 처리한 박막의 경우 p형 특성을 나타내는 상당량의 억셉터가 관련된 A0X (3.351eV), FA(3.283eV) 및 DAP (3.201eV) 피크가 관찰되었다. 향후 P 도핑된 ZnO 박막의 공정 조건과 후열 처리 조건을 최적화시킨다면, 차세대 광소자에 응용될 수 있는 매우 유망한 재료로 주목받을 것으로 기대된다.