• Korean Journal of Materials Research
• /
• v.21 no.3
• /
• pp.149-155
• /
• 2011

We investigated tribological characteristics of diamond-like carbon (DLC) in a condition with carbon nanotube (CNT) content of 1wt% in aqueous solution. Si-DLC films were deposited by radio frequency plasma enhanced chemical vapor deposition (RF-PECVD) process on Al6061 aluminum alloy. In this study, the deposition of DLC films was carried out in vacuum with a chamber pressure of 10-5 to 10-3 Torr achieved by mechanical pump followed by turbo molecular pump. The surface adsorbed oxygen on the Aluminum substrates was removed by passing Ar gas for 10 minutes. The RF power was maintained at 500W throughout the experiment. A buffer layer of HMDSO was deposited on the substrate to improve the adhesion of DLC coating. At this point CH4 gas was introduced in the chamber using gas flow controller and DLC coating was deposited on the buffer layer along with HMDSO for 50 min. The thickness of 1 ${\mu}m$ was obtained for DLC films on aluminum substrates The tribological properties of as synthesized DLC films were analyzed by wear test in the presence of dry air, water and lubricant such as CNT ink.

• Korean Journal of Materials Research
• /
• v.10 no.8
• /
• pp.525-531
• /
• 2000

Sb-doped tin oxide films were deposited on Cornig glass 1737 substrate by plasma enhanced chemical vapor deposition (PECVD) technique. The films deposited at different reaction parameters were then examined by using XRD and AFM. The relatively good crystalline thin film was formed at $450^{\circ}C$, input gas ratio R[$P_{SbCl}P_{{SnCl}_4}$]=1.12 and r.f. power 30W. The surface roughness of the film formed by PECVD compared to TCVD was more smooth. Higher concentration of Sb dopant, lower deposition temperature, and thinner thickness of deposited film led to de-creasing surface roughness of the formed thin films.

• Journal of the Korean Vacuum Society
• /
• v.7 no.3
• /
• pp.242-247
• /
• 1998

Hydrogenated amorphous carbon nitride[a-C:H(N)] films were deposited on p-type Si(100) at room temperature with bias voltage of 200 V by DC saddle-field plasma-enhanced chemical vapor deposition. Effects of the ratio of $N_2$ to $CH_4$($N_2/CH_4$), in the range of 0 and 4 on such properties as optical properties, microstucture, relative fraction of nitrogen and carbon, etc. of the films have been investigated. The thickness of the a-C:H(N) film was abruptly decreased with the addition of nitrogen, but at $N_2/CH_4$>0.5, the thickness of the film gradually decreased with the increase of the $N_2/CH_4$. The ratio of N to C(N/C) of the films was saturated at 0.25 with the increase of $N_2CH_4$. N-H, C≡N bonds of the films increased but C-H bond decreased with the increase of $N_2CH_4$.Optical band gap energy of the film decreased from 2.53 eV at the ratio of $N_2CH_4$=4.

• Journal of the Korean Vacuum Society
• /
• v.10 no.2
• /
• pp.182-188
• /
• 2001

Thin films of $SiO_xC_y$ deposited by means of PECVD(plasma enhanced chemical vapor deposition) using HMDSO(hexamethyldisiloxane)/$O_2$ were characterized. The effects of deposition conditions such as RF power, oxygen flow rate and hydrogen flow rate on the chemical bond structure, atomic composition, surface roughness and wear characteristics of the films were investigated by means of FTIR, XPS, AFM and Hazemeter. The deposition rate of $SiO_xC_y$ was greater than 100 nm/min, which is relatively high rate. The XPS results showed that the carbon content in a deposited film was lower than that of previous studies where different organosilicone materials were used. The optimum wear resistance was attained when RF power was 200 Watt and oxygen flow rate was 100 sccm. This study implies that the $HMDSO/O_2$ system is effective in forming a film with a lower carbon content and good abrasion resistance.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.36 no.12
• /
• pp.1171-1176
• /
• 2012

The selective patterning of a carbon nanotube (CNT) forest on a Si substrate has been performed using a femtosecond laser. The high shock wave generated by the femtosecond laser effectively removed the CNTs without damage to the Si substrate. This process has many advantages because it is performed without chemicals and can be easily applied to large-area patterning. The CNTs grown by plasma-enhanced chemical vapor deposition (PECVD) have a catalyst cap at the end of the nanotube owing to the tip-growth mode mechanism. For the application of an electron emission and biosensor probe, the catalyst cap is usually removed chemically, which damages the surface of the CNT wall. Precise control of the femtosecond laser power and focal position could solve this problem. Furthermore, selective CNT cutting using a femtosecond laser is also possible without any phase change in the CNTs, which is usually observed in the focused ion beam irradiation of CNTs.

• JSTS:Journal of Semiconductor Technology and Science
• /
• v.5 no.2
• /
• pp.131-135
• /
• 2005

The effect of different surface passivation films on blue or green (465-505 nm) InGaN/GaN multi-quantum well light-emitting diodes (LEDs) die were examined. $SiO_2$ or $SiN_x$ deposited by plasma enhanced chemical vapor deposition, or $Sc_2O_3$ or MgO deposited by rf plasma enhanced molecular beam epitaxy all show excellent passivation qualities. The forward current-voltage (I-V) characteristics were all independent of the passivation film used, even though the MBE-deposited films have lower interface state densities ($3-5{\times}10^{12}\;eV^{-1}\;cm^{-2}$) compared to the PECVD films (${\sim}10^{12}\;eV^{-1}\;cm^{-2}$), The reverse I-V characteristics showed more variation, hut there was no systematic difference for any of the passivation films, The results suggest that simple PECVD processes are effective for providing robust surface protection for InGaN/GaN LEDs.

• KSTLE International Journal
• /
• v.9 no.1_2
• /
• pp.22-25
• /
• 2008

This paper investigated the wetting and adhesion property of undulated DLC film with surface morphology controlled for a reduced real area of contact. The undulated DLC Films were prepared by 13.56 MHZ radio frequency plasma enhanced chemical vapor deposition (r.f. PECVD) by using nanoscale Cu dots surface on a Si (100) substrate. FE-SEM, AFM analysis showed that the after repeated deposition and plasma induced damage with Ar ions, the surface was nanoscale undulated. This phenomenon changed the surface morphology of DLC surface. Raman spectra of film with changed morphology revealed that the plasma induced damage with Ar ions significantly suppressed the graphitization of DLC structure. Also, it was observed that while the untreated flat DLC surfaces had wetting angle starting ranged from $72^{\circ}$ and adhesion force of 333ni. Had wetting angle the undulated DLC surfaces, which resemble the surface morphology of a cylindrical shape, increased up to $104^{\circ}$ and adhesion force decreased down to 11 nN. The measurements agree with Hertz and JKR models. The surface undulation was affected mainly by several factors: the surface morphology affinity to cylindrical shape, reduction of the real area of contact and air pockets trapped in cylindrical asperities of the surface.

• Proceedings of the Korean Vacuum Society Conference
• /
• 2014.02a
• /
• pp.381.2-381.2
• /
• 2014

In this study the amorphous carbon films were deposited by PECVD at the substrate temperature range of 250 to $600^{\circ}C$, and the process conditions of higher and lower precursor flow rate, respectively. The temperature was a main parameter to control the density and mirco-structures of carbon films, and their's properties depended with the process temperatrue are changed by controlling precursor flow rate. The precursor feeding rate affect on the plasma ion density and a deposition reactivity. This change of film properties was obtained the instrinsic stress, FT-IR & Raman analysis, refractive index (RI) and ext. coef. (k) measured by ellipsometer. In the process conditions of lower and higher flow rate of precursor it had a different intrinsic stress as a function of the substrate temperature.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2002.07b
• /
• pp.964-967
• /
• 2002

The effectiveness of silicon nitride SiNx surface passivation is investigated and quantified. This study adopted single-layer antireflection (SLAR) coating of SiNx for efficiency improvement of solar cell. The silicon nitride films were deposited by means of plasma enhanced chemical vapor deposition (PECVD) in planar coil reactor. The process gases used were pure ammonia and a mixture of silane and helium. The thickness and the refractive index on the films were measured by ellipsometry and chemical bonds were determined by using an FT-IR equipment. This films obtained were analyzed in term of hydrogen content, refractive index for gas flow ratio $(NH_3/SiH_4)$, and efficiency of solar cell. The polycrystalline silicon solar cells passivated by silicon nitride shows efficiency above 12.8%.

• Korean Journal of Metals and Materials
• /
• v.50 no.8
• /
• pp.613-618
• /
• 2012

We report on electrical and mechanical properties of silicon nitride ($SiN_x$) films deposited by a plasma enhanced chemical vapor deposition (PECVD) method at $200^{\circ}C$ from $SiH_4$ highly diluted in $N_2$. The films were also prepared from $SiH_4$ diluted in He for comparison. The $N_2$ dilution was also effective in improving adhesion of the $SiN_x$ films, fascilitating construction of thin film transistors (TFTs). Metal-insulator-semiconductor (MIS) and Metal-insulator-Metal (MIM) structures were used for capacitance-voltage (C-V) and current-voltage (I-V) measurements, respectively. The resistivity and breakdown field strength of the $SiN_x$ films from $N_2$-diluted $SiH_4$ were estimated to be $1{\times}10^{13}{\Omega}{\cdot}cm$, 7.4 MV/cm, respectively. The MIS device showed a hysteresis window and a flat band voltage shift of 3 V and 0.5 V, respectively. The TFTs fabricated by using these films showed a field-effect mobility of $0.16cm^2/Vs$, a threshold voltage of 3 V, a subthreshold slope of 1.2 V/dec, and an on/off ratio of > $10^6$.