• Proceedings of the Korean Vacuum Society Conference
• /
• 2016.02a
• /
• pp.294.2-294.2
• /
• 2016

Graphene, a sigle atomic layered structure of graphite, has drawn many scientific interests for attractive future electronics and optoelectronics beyond silicon-based technology because of its robust physical, optical, and electrical properties. But high metal-graphene contact resistance prevents the successful integration of high speed graphene devices and circuits, although pristine graphene is known to have a novel carrier transport property. Meanwhile, in the recently reported metal-graphene contact studies, there are many attempts to reduce the metal-graphene contact resistance, such as doping and one-dimensional edge contact. However, there is a lack of quantitative analysis of the edge contact scheme through variously designed patterns with different metal contact. We first investigate the effets of edge contact (metal-graphene interface) on the contact resistance in terms of edge pattern design through patterning (photolithography + plasma etching) and electral measurements. Where the contact resistance is determined using the transfer length method (TLM). Finally, we research the role of metal-kind (Palladium, Copper, and Tianium) on the contact resistance through the edge-contacted devices, eventually minimizing contact resistance down to approximately $23{\Omega}{\cdot}{\mu}m$ at room temperature (approximately $19{\Omega}{\cdot}{\mu}m$ at 100 K).

• Journal of the Semiconductor & Display Technology
• /
• v.17 no.4
• /
• pp.66-69
• /
• 2018

This study was researched the electrical properties of semiconductor devices such as ITO, $SiO_2$, $V_2O_5$ thin films. The films of ITO, $SiO_2$, $V_2O_5$ were deposited by the rf magnetron sputtering system with mixed gases of oxygen and argon to generate the plasma. All samples were cleaned before deposition and prepared the metal electrodes to research the current-voltage properties. The electrical characteristics of semiconductors depends on the interface's properties at the junction. There are two kinds of junctions such as ohmic and schottky contacts in the semiconductors. In this study, the ITO thin film was shown the ohmic contact properties as the linear current-voltage curves, and the electrical characteristics of $SiO_2$ and $V_2O_5$ films were shown the non-linear current-voltage curves as the schottky contacts. It was confirmed that the electronic system with schottky contacts enhanced the electronic flow owing to the increment of efficiency and increased the conductivity. The schottky contact was only defined special characteristics at the semiconductor and the interface depletion layer at the junction made the schottky contact which has the effect of leakage current cutoff. Consequently the semiconductor device with shottky contact increased the electronic current flow, in spite of depletion of carriers.

• Journal of the Semiconductor & Display Technology
• /
• v.16 no.2
• /
• pp.9-14
• /
• 2017

$ISnO_2$ thin films were prepared on p-type and n-type Si substrates to research the interface characteristics between $SnO_2$ and substrate. After the annealing processes, the amorphous structure was formed at the interface to make a Schottky contact. The O 1s spectra showed the bond of 530.4 eV as an amorphous structure, and the Schottky contact. The analysis by the deconvoluted spectra was observed the drastic variation of oxygen vacancies at the amorphous structure because of the depletion layer is directly related to the oxygen vacancy. $SnO_2$ thin film changed the electrical properties depending on the characteristics of substrates. It was confirmed that it is useful to observe the Schottky contact's properties by complementary using the XPS analysis and I-V measurement.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.59 no.1
• /
• pp.130-133
• /
• 2010

Although many structures based on $SnO_2$ nanowires have been demonstrated, there is a limitation towards practical application due to the unwanted contact potential between the metal electrode and the $SnO_2$ nanowire. This is mostly due to the presence of the native oxide layer that acts as an insulator between the metal contact and the nanowire. In this study the contact properties between Ti/Au contacts and a single $SnO_2$ nanowire was compared to the electrical properties of a contact without the oxide layer. RIE(Reactive Ion Etching) is used to selectively remove the oxide layer from the contact area. The $SnO_2$ nanowires were synthesized by chemical vapor deposition (CVD) and dispersed on a $Si/Si_3N_4$ substrate. The Ti/Au (20nm/100nm) electrodes were formed bye-beam lithography, e-beam evaporation and a lift-off process.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2001.07a
• /
• pp.1065-1068
• /
• 2001

Effects of compacting pressure on the electrical and sintering characteristics of Cu25Cr contact material have been investigated. Cu25Cr contact materials were prepared by solid and liquid-phase sintering methods varying compacting pressure. Influence of compacting pressure on electrical characteristics were investigated in the cylindrical stainless-steel vessel using L-C resonant circuit. The physical and electrical properties of solid-phase sintered Cu25Cr material were found to be improved by increased compacting pressure. On the other hand, it was found that compacting pressure had little influence in case of liquid-phase sintered Cu25Cr material. After conditioning, contact resistance of Cu25Cr material was decreased regardless of compacting pressure. With increased compacting pressure, interrupting ability was shown to be increased.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2003.07b
• /
• pp.834-837
• /
• 2003

In this study, Ohmic contacts make on 3C-SiC using TiN. Ohmic contact resistivity of TiN/3C-SiC was evaluated. Specific contact resistance was calculated by Circular-TLM(transmission line model) method and physics properties were measured using XRD, SEM, respectively. TiN contact is stable at high temperatures and a good diffusion barrier material. The TiN/3C-SiC contacts are thermally stable to annealing temperatures up to $1000^{\circ}C$. The TiN thin-film depostied on 3C-SiC substraes have good electrical properties. Therefore, the TiN/3C-SiC contact can be usefully applied for high-temperature MEMS applications over $500^{\circ}C$.

• Proceedings of the KIEE Conference
• /
• 1995.11a
• /
• pp.352-354
• /
• 1995

The optical and electrical properties of High Speed AlGaAs infrared LED by using metal wet etch process instead of metal lift-off process are investigated. The power out increases when metal contact is patterned by wet etch process. Forward voltage and Reverse voltage for metal wet etch process represent higher value than the metal lift-off process. The aging effect of power out also indicates good results with wet etch process. The wet etch process for metal contact reveals reliable LED device properties.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.57 no.1
• /
• pp.46-51
• /
• 2008

Extra-high voltage(EHV) disconnecting switch(DS) consists of the electrical contacts and mechanical parts which actuate the contacts. When the short-circuit condition occurs, a large amount of current flows through the electrical contact in disconnecting switches and this causes considerable temperature rise due to Joule heating. If the temperature rise is higher than the melting point of contact material, the DS contact becomes melting and cannot be usable anymore. For this reason, the analysis for capability of carrying short-circuit current in DS contacts must be performed at a design stage. Here, we proposed a numerical technique for evaluating the capability of carrying short-circuit current at electrical contacts in EHV DS. In this numerical approach, the mechanical and thermal analyses were simulated to check the capability of carrying short-circuit current. First, the applied pressure at contact parts was analyzed considering the mechanical properties, and then contact resistance was calculated by an empirical equation. Finally, thermal analysis was performed with resistance variation at electrical contacts. To verify these numerical results, the distributions of temperature in DS were experimentally measured and compared with each other. The results from experiments were agreed well with those from the proposed numerical simulations.

• KSTLE International Journal
• /
• v.2 no.1
• /
• pp.22-28
• /
• 2001

A resin bonded copper-graphite brush was investigated to evaluate the characteristics electrical signal transmission through a sliding contact as a function of the relative amount of graphite and copper in the brush. Particular attention was given to the correlation between electrical signal fluctuation and tribological properties in an electrical sliding contact system. A ring-on-block type tribotester was used for this experiment and the ring was made from pure copper. Results showed that a copper-graphite brush at a particular composition range exhibited the most stable frictional behavior with a minimum voltage drop. The amount of voltage drop at the friction interface was affected by the surface roughness, transfer film formation at the friction interface, and the real area of contact. Microscopic observations and the surface analysis showed a good agreement with the results from this experiment. The results also indicated that the electrical signal flunctuation was directly associated with the oscillation of the coefficient of friction during sliding by nanoscale variation of contacts at the friction interface.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.61 no.10
• /
• pp.1561-1564
• /
• 2012

In this work, we have fabricated the nanocrystalline carbon films by using unbalanced magnetron sputtering method with graphite and Ti targets for contact strip application of electrical railway. The power density of graphite target was fixed and the power density was increased for the increase of Ti concentration in TiC films. We investigated the hardness, surface roughness, contact angle, resistivity, HRTEM and XPS of TiC films with Ti concentration. The hardness and resistivity were improved with increasing Ti concentration. These results indicate that the improvement of hardness and resistivity is related to the increase of sp2 clusters in TiC films.