• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.11a
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• pp.521-524
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• 2001

In this letter, we report on the investigation of Ti, Pt/Si/Ti Ohmic contacts to p-type 4H-SiC. The contacts were formed by a 2-step vacuum annealing at 500$^{\circ}C$ for 1h, 950$^{\circ}C$ for 10 min respectively. The contact resistances were measured using the transmission line model method, which resulted in specific contact resistivities in the 3.5x10$\^$-3/ and 6.2x10$\^$-4/ ohm/$\textrm{cm}^2$, and the physical properties of the contacts were examined using x-ray diffraction, microscopy, AES(auger electron spectroscopy). AES analysis has shown that, at this anneal temperature, there was a intermixing of the Ti and Si, migration of into SiC. Overlayer of Pt had the effect of decreasing the specific contact resistivity and improving the surface morphology of the annealed contact.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.16 no.7
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• pp.557-563
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• 2003

SiC has been an useful material for the high voltage, high temperature, and high frequency devices, however, the required high process temperature to activate the implanted p-type dopants has hindered further developments. In this study, we report, for the first time, on the laser activation of implanted Al and non-alloyed Mo ohmic contacts and its application to MOSFET fabrication. The contact and sheet resistance measured from CTLM patterns have decreased by increasing laser power, and the lowest values are 3.9 $K\Omega$/$\square$ and 1.3 $\times$ 10$^{-3}$ $\Omega$-cm$^2$, respectively, at the power density of 1.45 J/cm$^2$ The n-MOSFETs fabricated on laser activated p-well exhibit well-behaved I-V characteristics and threshold voltage reduction by reverse body voltage. These results prove that the laser process for implant activation is an alternative low temperature technology applicable to SiC devices.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.15 no.5
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• pp.449-454
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• 2002

The use of a thin film of indium between the ITO and the $n^+-lnP$ contact layers for InP/InGaAs HPTs was studied without degrading its excellent optical transmittance properties. $ITO/n^+-lnP$ ohmic contact was successfully achieved by the deposition of indium and annealing. The specific contact resistance of about $6.6{\times}10^{-4}\Omega\textrm{cm}^2$ was measured by use of the transmission line method (TLM). However, as the thermal annealing was just performed to $ITO/n^+-lnP$ contact without the deposition of indium between ITO and $n^+-lnP$, it exhibited Schottky characteristics. In the applications, the DC characteristics of InP/InGaAs HPTs with ITO emitter contacts was compared with those of InP/InGaAs HBTs with the opaque emitter contacts.

• Journal of the Korean institute of surface engineering
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• v.43 no.2
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• pp.47-50
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• 2010

This work discusses a two-step electroless plating method for preparing a Pt thin film on p-type InGaAs substrate, which is defined as Pt I and Pt II. A thin Pt catalytic layer formed in Pt I bath on the substrate at $65^{\circ}C$. In the following Pt II bath, thick Pt films then easily grew on the sensitized layer on InGaAs previously formed in the Pt I bath. The growth of Pt film is strongly influenced by the plating temperature and pH value. To study the plating time effect, the plating of Pt II bath is 5 to 40 min at $80^{\circ}C$ after using Pt I bath at 50~$65^{\circ}C$ for 5min of pH 8~13. Pt film for ohmic contact to p-type InGaAs was successfully prepared by using the two-step Pt electroless plating.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.11a
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• pp.179-180
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• 2007

반도체의 최소 회로 선폭이 감소함에 따라 Contact 저항이 크게 증가하게 된다. Contact 저항을 낮추기 위하여 Tungsten Metal Contact을 일반적으로 사용하며, Si 기판과의 Ohmic 접촉 및 WF6의 Fluorine과 Si 반응을 억제하기 위한 Barrier Metal로 Ti/TiN 이중막을 사용한다. 본 논문에서는 90nm급 이하 제품의 CVD Ti/TiN Barrier Metal이 유발하는 불량 현상과 원인 규명에 대하여 연구하였으며, Ohmic Contact형성을 위해 TiSix형성 최적화 방안에 대해 정리하였다.

• Korean Journal of Materials Research
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• v.25 no.3
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• pp.119-124
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• 2015

This paper investigates the change of the percolation threshold in the carbon powder-filled polystyrene matrix composites based on the experimental results of changes in the resistivity and relative permittivity of the carbon powder filling, the electric field dependence of the current, and the critical exponent of conductivity. In this research, the percolation behavior, the critical exponent of resistivity, and electrical conduction mechanism of the carbon powder-filled polystyrene matrix composites are discussed based on a study of the overall change in the resistivity. It was found that the formation of infinite clusters is interrupted by a tunneling gap in the volume fraction of the carbon powder filling, where the change in the resistivity is extremely large. In addition, it was found that the critical exponent of conductivity for the universal law of conductivity is satisfied if the percolation threshold is estimated at the volume fraction of carbon powder where non-ohmic current behavior becomes ohmic. It was considered that the mechanism for changing the gaps between the carbon powder aggregates into ohmic contacts is identical to that of the connecting conducting phases above the percolation threshold in a random resister network system. The electric field dependence is discussed with a tunneling mechanism. It is concluded that the percolation threshold should be defined at this volume fraction (the second transition of resistivity for the carbon powder-filled polystyrene matrix composites) of carbon powder.

• The Transactions of the Korean Institute of Power Electronics
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• v.24 no.5
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• pp.365-371
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• 2019

This study shows the feasibility of the parameter of the 1st RC parallel equivalent circuit as a factor of the heat generation of lithium-ion cell. The internal resistance of a lithium-ion cell consists of ohmic and polarization resistances. The internal resistances at various SOCs of the lithium-ion cell are obtained via an electrical characteristic test. The internal resistance is inversely obtained through the amount of heat generated during the experiment. By comparing the resistances obtained using the two methods, the summation of ohmic and polarization resistances is identified as the heating factor of lithium-ion battery. Finally, the amounts of heat generated from the 2C, 3C, and 4C-rate discharge experiments and the COMSOL multiphysics simulation using the summation of ohmic and polarization resistances as the heating parameter are compared. The comparison shows the feasibility of the electrical parameters of the 1st RC parallel equivalent circuit as the heating factor.

• Korean Journal of Materials Research
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• v.9 no.10
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• pp.1012-1017
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• 1999

Low resistance ohmic contacts to the Si-doped $\textrm{In}_{0.17}\textrm{Ga}_{0.83}\textrm{N}$(~$\times10^{19}\textrm{cm}^{-3}$) were obtained using the W metallization schemes. Specific contact resistance decreased with increasing annealing temperature. The lowest resistance is obtained after a nitrogen ambient annealing at $950^{\circ}C$ for 90 s, which results in a specific contact resistance of $2.75\times10^{-8}\Omega\textrm{cm}^{-3}$. Interfacial reactions and surface are analyzed using x-ray diffraction and scanning electron microscopy (SEM). The X-ray diffraction results show that the reactions between the W film and the $\textrm{In}_{0.17}\textrm{Ga}_{0.83}\textrm{N}$ produce a $\beta$-$W_2N$ phase at the interface. The SEM result shows that the morphology of the contacts is stable up to a temperature as high as $850^{\circ}C$. Possible mechanisms are proposed to describe the annealing temperature dependence of the specific contact resistance.

• Proceedings of the Korean Society for Food Science of Animal Resources Conference
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• 1997.11a
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• pp.31-39
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• 1997

• Proceedings of the Korean Vacuum Society Conference
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• 1999.02a
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• pp.55-55
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• 1999