• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.21 no.11
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• pp.968-972
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• 2008

Ni/Ti/Al multilayer system ('/'denotes the deposition sequence) was tested for low-resistance ohmic contact formation to Al-implanted p-type 4H-SiC. Ni 30 nm / Ti 50 nm / Al 300 nm layers were sequentially deposited by e-beam evaporation on the 4H-SiC samples which were implanted with Al (norminal doping concentration = $4\times10^{19}cm^{-3}$) and then annealed at $1700^{\circ}C$ for dopant activation. Rapid thermal anneal (RTA) temperature for ohmic contact formation was varied in the range of $840\sim930^{\circ}C$. Specific contact resistances were extracted from the measured current vs. voltage (I-V) data of linear- and circular transfer length method (TLM) patterns. In constrast to Ni contact, Ni/Ti/Al contact shows perfectly linear I-V characteristics, and possesses much lower contact resistance of about $2\sim3\times10^{-4}\Omega{\cdot}cm^2$ even after low-temperature RTA at $840^{\circ}C$, which is about 2 orders of magnitude smaller than that of Ni contact. Therefore, it was shown that RTA temperature for ohmic contact formation can be lowered to at least $840^{\circ}C$ without significant compromise of contact resistance. X-ray diffraction (XRD) analysis indicated the existence of intermetallic compounds of Ni and Al as well as $NiSi_{1-x}$, but characteristic peaks of $Ti_{3}SiC_2$, a probable narrow-gap interfacial alloy responsible for low-resistance Ti/Al ohmic contact formation, were not detected. Therefore, Al in-diffusion into SiC surface region is considered to be the dominant mechanism of improvement in conduction behavior of Ni/Ti/Al contact.

• Proceedings of the Materials Research Society of Korea Conference
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• 1999.11a
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• pp.80-80
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• 1999

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.06a
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• pp.208-209
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• 2008

Ni/Ti/Al multilayer system was tested for low-resistance ohmic contact formation to Al-implanted p-type 4H-SiC. Compared with conventional process using Ni, Ni/Ti/Al contact shows perfect ohmic behavior, and possesses much lower contact resistance of about $2.5\times10^{-4}\Omega{\cdot}cm^2$ after $930^{\circ}C$ RTA, which is about 2 orders of magnitude smaller than that of Ni contact. Contact resistance gradually increased as the RTA temperature was lowered in the range of 840 ~ $930^{\circ}C$, and about $3.4\times10^{-4}\Omega{\cdot}cm^2$ was obtained at the lowest RTA temperature of $840^{\circ}C$. Therefore, it was shown that RTA temperature for ohmic contact formation can be lowered to at least $840^{\circ}C$ without significant compromise of contact resistance.

• Journal of the Korean Institute of Telematics and Electronics
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• v.26 no.9
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• pp.1381-1387
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• 1989

For the fabrication of ohmic contact to p-type GaAs, In Liquid Metal Ions were implanted into p-type GaAs (Zn:1.5x10**19/cm**3). After the samples were processed by Infrared rapid thermal annealing (IRTA0 or Furance Annealing (FA), I-V and specific contact contact resistivity were measured. Specific contact resistivity was found to be 1.7x10**-5 \ulcorner-cm\ulcornerin IRTA 750\ulcorner, 10 sec annealed sample. The surface characteristics of the samples were investigated with SEM, RHEED, AES. From these results we can know that implanted In ions were formed mixing layer of InAs at the surface.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.07a
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• pp.290-293
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• 2003

Ohmic contact characteristics of Al ion implanted n-type SiC wafer were investigated. Al ions implanted with high dose to obtain the final concentration of $5{\times}10^{19}/cm^3$, then annealed at high temperature. Firstly, B ion ion implanted p-well region were formed which is needed for fabrication of SiC devices such as DIMOSFET and un diode. Secondly, Al implanted high dose region for ohmic contact were formed. After ion implantation, the samples were annealed at high temperature up to $1600^{\circ}C\;and\;1700^{\circ}C$ for 30 min in order to activate the implanted ions electrically. Both the inear TLM and circular TLM method were used for characterization. Ni/Ti metal layer was used for contact metal which is widely used in fabrication of ohmic contacts for n-type SiC. The metal layer was deposited by using RF sputtering and rapid thermal annealed at $950^{\circ}C$ for 90sec. Good ohmic contact characteristics could be obtained regardless of measuring methods. The measured specific contact resistivity for the samples annealed at $1600^{\circ}C\;and\;1700^{\circ}C$ were $1.8{\times}10^{-3}{\Omega}cm^2$, $5.6{\times}10^{-5}{\Omega}cm^2$, respectively. Using the same metal and same process of the ohmic contacts in n-type SiC, it is found possible to make a good ohmic contacts to p-type SiC. It is very helpful for fabricating a integrated SiC devices. In addition, we obtained that the ratio of the electrically activated ions to the implanted Al ions were 10% and 60% for the samples annealed at $1600^{\circ}C\;and\;1700^{\circ}C$, respectively.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.15 no.6
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• pp.231-238
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• 2015

In this paper, we have studied a sheet resistance property of N- and P-type thin films deposited on ITO glass by use of RF magnetron sputtering. The N-type samples which has the deposition condition of 150W RF power, shows the highest current value, and the samples deposited for 15 minutes shows a better Ohmic contact property. As the substrate temperature, RF power and deposition time are increased, the sheet resistance of the samples is increased, and the low sheet resistance sample shows a better I-V property. The P-type samples shows the highest current value by 150W RF power condition as similar as N-type samples. and the samples deposited for 20 minutes shows a better ohmic contact property. The sheet resistance of the both types samples is increased as increasing RF power and deposition time.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.31 no.1
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• pp.6-10
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• 2018

Ni germanide (NiGe) is a promising alloy material with small contact resistance at the source/drain (S/D) of Ge MOSFETs. However, it is necessary to reduce the specific contact resistance between NiGe and the doped Ge S/D region in high-performance MOSFETs. In this study, a novel method is proposed to reduce the specific contact resistance between NiGe and p-type Ge (p-Ge) using a Tb interlayer. The specific contact resistance between NiGe and p-Ge was successfully decreased with the introduction of the Tb interlayer. To investigate the mechanism behind the reduction in the specific contact resistance, the elemental distribution and crystalline structure of NiGe were analyzed using secondary ion mass spectroscopy and X-ray diffraction. It is likely that the reduction in specific contact resistance was caused by an increase in the concentration of boron in the space between NiGe and p-Ge due to the influence of the Tb interlayer.

• Proceedings of the Korean Vacuum Society Conference
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• 2015.08a
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• pp.122.2-122.2
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• 2015

n-type 실리콘은 p-type과 비교하여 더 높은 소수캐리어 lifetime 으로 금속 불순물에 대하여 더 좋은 내성을 갖는다. 고효율 실리콘 태양전지를 위하여 p-type 웨이퍼를 n-type으로 교체하여 빛을 조사했을 때, 광전자들이 형성되어 p-type과 비교하여 더 좋은 lifetime 안정성을 갖는다. n-type 태양전지의 전면 전극은 AgAl paste로 형성하였다. AgAl 페이스트는 소성 온도와 밀접하게 관련되어 전극의 접합 깊이에 영향을 미친다. p+ emitter 층에 파고드는 금속 접촉의 최적화된 깊이는 접촉 저항에 영향을 미치는 중요한 요소이다. 본 연구에서는 소성 조건을 변화시킴으로써, 금속 깊이의 효과적인 형성을 위한 소성 조건을 최적화하였다. $670^{\circ}C$ 이하의 온도에서 소성을 진행 하였을 때, 충분한 접촉 깊이를 형성하지 못하여 높은 접촉저항을 갖는다. 소성 온도가 증가함에 따라, 접촉 저항은 감소하였다. 최적 소성 온도 $865^{\circ}C$에서 측정된 접촉저항은 $5.99mWcm^2$이다. $900^{\circ}C$ 이상에서 contact junction은 emitter를 통과하여 실리콘과 결합하였다. 그 결과로 접촉저항 shunt가 발생한다.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.53 no.10
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• pp.495-499
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• 2004

Characteristics of ohmic Ni/Si/Ni contacts to n-type 4H-SiC are investigated systematically. The ohmic contacts were formed by annealing Ni/Si/Ni sputtered sequentially The annealings were performed at 950℃ using RTP in vacuum ambient and N₂ ambient, respectively. The specific contact resistivity(p/sub c/), sheet resistance(R/sub s/), contact resistance (R/sub c/) transfer length(L/sub T/) were calculated from resistance(R/sub T/) versus contact spacing(d) measurements obtained from TLM(transmission line method) structure. While the resulting measurement values of sample annealed at vacuum ambient were p/sub c/ = 3.8×10/sup -5/Ω㎠, R/sub c/ = 4.9 Ω and R/sub T/ = 9.8 Ω, those of sample annealed at N₂ ambient were p/sub c/ = 2.29×10/sup -4/Ω㎠, R/sub c/ = 12.9 Ω and R/sub T/ = 25.8 Ω. The physical properties of contacts were examined using XRD 3nd AES. The results showed that nickel silicide was formed on SiC and Ni was migrated into SiC. This result indicates that Ni/Si/Ni ohmic contact would be useful in high performance electronic devices.

• Asian-Australasian Journal of Animal Sciences
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• v.12 no.2
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• pp.165-168
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• 1999

To determine the effects of genetic and environmental influences on cell mediated immune (CMI) responses in broiler rabbits, contact sensitivity to 2,4-Dinitrochlorobenzene (DNCB) was assessed in three temperate broiler breeds of rabbits, namely Soviet Chinchilla, New Zealand White and Grey Giant. The feasibility of using the contact sensitivity to DNCB as a marker trait in selection for disease resistance was examined. There were highly significant differences between breeds (p<0.01) in initial skin thickness and contact sensitivities to DNCB at 24, 48 and 72 hours. Initial skin thickness was greatest in the Soviet Chinchilla breed (mean 2.2484 mm), and was significantly greater (p<0.01) in males (2.4963 mm) than in females (1.7846 mm) (p<0.01). Highest contact sensitivity to DNCB was in the New Zealand White breed with mean increase in skin thickness of 1.1884, 0.9072 and 0.5879 mm at 24, 48 and 72 hours post challenge respectively. Delayed type hypersensitivity (DTH) reaction to DNCB at 24 hours post challenge had a highly significant association (p<0.01) with the incidence of body mange in rabbits. The results indicated a lowered contact sensitivity to DNCB at 24 hours post challenge was associated significantly (p<0.01) with an increase in incidence and severity of body mange, suggesting its potential value as a marker. The correlation s among contact sensitivities at 24, 48 and 72 hours were positive and highly significant (p<0.01); correlations between initial skin thickness and contact sensitivities were negative and highly significant (p<0.01). Another notable significant correlation was between body weight and delayed type hypersensitivity at 24 hours indicating that an enhanced CMI might be associated with better growth rate and general wellbeing.