• Korean Journal of Materials Research
• /
• v.16 no.10
• /
• pp.619-623
• /
• 2006

Selective vapor deposition of conductive poly(3,4-ethylenedioxythiophene) (PEDOT), thin films has been carried out on self assembled monolayers patterned oxide substrate. Since the 3,4-ethylenedioxythiophene(EDOT) monomer can be polymerized only in the presence of oxidant such as $FeCl_3$, the PEDOT thin film is selectively deposited on patterned $FeCl_3$, which only adsorbs on the partly removed SAMs region due to the inability of $FeCl_3$ to adsorb on SAMs. Therefore, the partly removed SAMs can act as an adsorption layer for the $FeCl_3$ and also as a glue layer for the deposition of PEDOT, resulting in the significantly increased adhesion of PEDOT to $SiO_2$ substrate. The use of UV lithography and Cr patterned quartz mask provided the formation of SAMs patterns on oxide substrates, which allowed for the selective deposition of conductive PEDOT thin films.$^{oo}The$ new process was successfully developed for the selective deposition of PEDOT thin films on SAMs patterned oxide substrate, providing a new way for the patterning of vapor phase deposition of PEDOT thin films with accurate alignment and addressing the inherent adhesion issues between PEDOT and dielectrics.

• Proceedings of the Korean Institute of Surface Engineering Conference
• /
• 2011.05a
• /
• pp.33-35
• /
• 2011

Films of CrAlN and CrZrN were deposited on a steel substrate by closed field unbalanced magnetron sputtering, and their oxidation behaviors were investigated. CrAlN films consisted of dense, polycrystalline CrN and AlN fine columns. The formed oxides consisted primarily of crystalline $Cr_2O_3$ incorporated with $Al_2O_3$. The oxide layers were thin and compact so as to make CrAlN films more protective than CrN films. In case of CrZrN films, Zr atoms were dissolved in the CrN phase. Zr atoms advantageously refined the columnar structure, reduced the surface roughness, and increased the micro-hardness. However, the addition of Zr did not increased oxidation resistance, mainly because Zr was not a protective element. All the deposited films displayed relatively good oxidation resistance, owing to the formation of the highly protective $Cr_2O_3$ on their surface. The $Cr_{40}Zr_9N$ and $Cr_{31}Zr_{16}N$ films oxidized to $Cr_2O_3$ as the major phase and ${\alpha}-ZrO_2$ as the minor one, whereas the CrN film oxidized to $Cr_2O_3$.

• Journal of Magnetics
• /
• v.13 no.3
• /
• pp.88-91
• /
• 2008

This study examined the effect of Sn co-doping on the transport and magnetic properties of Cr-doped $In_2O_3$ thin films grown on (100) silicon substrates by pulsed laser deposition. The experimental results showed that Sn co-doping enhances the magnetization and appearance of the anomalous Hall effect, and increases the carrier (electron) concentration. These results suggest that the conduction carrier plays an important role in enhancing the ferromagnetism of a laser-deposited Cr-doped $In_2O_3$ film, which may have applications in transparent oxide semiconductor spin electronics devices.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.23 no.10
• /
• pp.763-766
• /
• 2010

By improving the conducting process of metal source/drain (S/D) in direct contact with the channel, schottky barrier metal-oxide-semiconductor field effect transistors (SB MOSFETs) reveal low extrinsic parasitic resistances, offer easy processing and allow for well-defined device geometries down to the smallest dimensions. In this work, we investigated the arrhenius plots of the SB MOSFETs with different S/D schottky barrier (SB) heights between simulated and experimental current-voltage characteristics. We fabricated SB MOSFETs using difference S/D metals such as Cr (${\Phi}_{Cr}$ ~4.5 eV) and Ni (${\Phi}_{Ni}$~5.2 eV), respectively. Schottky barrier height (${\Phi}_B$) of the fabricated devices were measured to be 0.25~0.31 eV (Cr-S/D device) and 0.16~0.18 eV (Ni-S/D device), respectively in the temperature range of 300 K and 475 K. The experimental results have been compared with 2-dimensional simulations, which allowed bandgap diagram analysis.

• Journal of the Korean Institute of Telematics and Electronics A
• /
• v.31A no.10
• /
• pp.108-113
• /
• 1994

The characteristics of the oxidation prevention layers for the copper metallization were investigated. The thin films such as Cr, TiN and Al were used as the oxidation prevention layers for copper. Ultra thin aluminum films were found to prevent the oxidation of copper up to the highest oxidation annealing temperature among the barrier layers examined in this study. It was found that oxygen did not diffuse into copper through aluminum films because of the aluminum oxide layer formed on the aluminum surface and the ultra thin aluminum film could be a good oxidation barrier layer for the copper metallization.

• Proceedings of the Korean Vacuum Society Conference
• /
• 2012.08a
• /
• pp.254-255
• /
• 2012

Interest in nano-crystalline silicon (nc-Si) thin films has been growing because of their favorable processing conditions for certain electronic devices. In particular, there has been an increase in the use of nc-Si thin films in photovoltaics for large solar cell panels and in thin film transistors for large flat panel displays. One of the most important material properties for these device applications is the macroscopic charge-carrier mobility. Hydrogenated amorphous silicon (a-Si:H) or nc-Si is a basic material in thin film transistors (TFTs). However, a-Si:H based devices have low carrier mobility and bias instability due to their metastable properties. The large number of trap sites and incomplete hydrogen passivation of a-Si:H film produce limited carrier transport. The basic electrical properties, including the carrier mobility and stability, of nc-Si TFTs might be superior to those of a-Si:H thin film. However, typical nc-Si thin films tend to have mobilities similar to a-Si films, although changes in the processing conditions can enhance the mobility. In polycrystalline silicon (poly-Si) thin films, the performance of the devices is strongly influenced by the boundaries between neighboring crystalline grains. These grain boundaries limit the conductance of macroscopic regions comprised of multiple grains. In much of the work on poly-Si thin films, it was shown that the performance of TFTs was largely determined by the number and location of the grain boundaries within the channel. Hence, efforts were made to reduce the total number of grain boundaries by increasing the average grain size. However, even a small number of grain boundaries can significantly reduce the macroscopic charge carrier mobility. The nano-crystalline or polymorphous-Si development for TFT and solar cells have been employed to compensate for disadvantage inherent to a-Si and micro-crystalline silicon (${\mu}$-Si). Recently, a novel process for deposition of nano-crystralline silicon (nc-Si) thin films at room temperature was developed using neutral beam assisted chemical vapor deposition (NBaCVD) with a neutral particle beam (NPB) source, which controls the energy of incident neutral particles in the range of 1~300 eV in order to enhance the atomic activation and crystalline of thin films at room temperature. In previous our experiments, we verified favorable properties of nc-Si thin films for certain electronic devices. During the formation of the nc-Si thin films by the NBaCVD with various process conditions, NPB energy directly controlled by the reflector bias and effectively increased crystal fraction (~80%) by uniformly distributed nc grains with 3~10 nm size. The more resent work on nc-Si thin film transistors (TFT) was done. We identified the performance of nc-Si TFT active channeal layers. The dependence of the performance of nc-Si TFT on the primary process parameters is explored. Raman, FT-IR and transmission electron microscope (TEM) were used to study the microstructures and the crystalline volume fraction of nc-Si films. The electric properties were investigated on Cr/SiO2/nc-Si metal-oxide-semiconductor (MOS) capacitors.

• Proceedings of the Korean Society for Technology of Plasticity Conference
• /
• 2004.08a
• /
• pp.285-293
• /
• 2004

Oxidation behavior of 304 and 430 stainless steel were studied using thin film X-ray analysis and glow discharge spectrum analysis (here-after GDS). The oxidation layer of 304 stainless steel was composed of $Cr_2O_3\;and\;FeCrO_4$ and its thickness was about $1.5{\mu}m$ after $1\~5$ minutes of annealing at $1120^{\circ}C$ open air. However, the oxidation layer of 430 stainless steels was mainly composed of $Cr_2O_3$ and its typical thickness was 0.5um after $1\~5$ minutes of annealing at $1000^{\circ}C$ open air. Electro-chemical analysis revealed that the descaling of oxidation layer could be activated by Fe, Cr dissolution from the matrix behind the oxidation layer at the current density of $5\~10ASD$ and by Fe, Cr-oxide dissolution from the oxidation layer at the current density over than 10ASD. Electrolytic stripping of 430 and 304 revealed the intial incubation period of descaling by oxygen evolving at low current density range such as $5\~10ASD$. However the dissolution of oxide layer was occurred when applying the anodic current of $10\~20ASD$ on 430 and 304 stainless steels. It was suggested that the electrolytic pickling of high Cr bearing stainless steel such as 430 and 304 seemed to be the more effective in the high current density range such as $10\~20ASD$ than the low current density range such as $5\~10ASD$.

• Proceedings of the Materials Research Society of Korea Conference
• /
• 2003.03a
• /
• pp.126-126
• /
• 2003

유기트랜지스터에 관한 연구는 1980년 이후부터 시작되었으나 근래에 들어 전 세계적으로 본격적인 연구가 진행되고 있다. 제작공정이 간단하고 비용이 저렴하며 충격에 의해 깨지지 않고 구부리거나 접을 수 있는 전자 회로 기판이 미래의 산업에 필수적인 요소가 될 것으로 예상되고 있으며 이러한 요구를 충족시킬 수 있는 유기트랜지스터의 개발은 아주 중요한 연구분야로 대두되고 있다. 본 연구에서는 표면처리에 따른 contact angle, I-V 특성곡선, 표면 morphology 등의 결과로부터 dry cleaning 한 것이 wet cleaning한 것보다 왜 좋은지를 논하고자 한다. 먼저 N-type SiO$_2$ 기판을 이용하여 back면의 oxide층을 제거한 후, back gate용으로 사용하기 위하여 sputtering장치로 Au/Cr을 증차하였다. 그리고 기판에 앞면을 photolithography 공정을 이용하여 Au/Cr를 1000$\AA$ 증착 하여 source-, drain-eldctrode를 제조하였다. 그리고 SiO$_2$ 기판의 표면처리를 달리하여 그 위에 유기박막을 증착하여 특성을 비교하였다.

• Journal of Sensor Science and Technology
• /
• v.33 no.1
• /
• pp.40-47
• /
• 2024

The creation of vertically aligned one-dimensional (1D) nanostructures through the decoration of n-type tin oxide (SnO₂) on p-type chromium oxide (Cr₂O₃) constitutes an effective strategy for enhancing gas sensing performance. These heterostructures are deposited in multiple stages using a glancing angle deposition technique with an electron beam evaporator, resulting in a reduction in the surface porosity of the nanorods as SnO₂ is incorporated. In comparison to Cr₂O₃ films, the bare Cr₂O₃ nanorods exhibits a response 3.3 times greater to 50 ppm H₂S at 300℃, while the SnO₂-decorated Cr₂O₃ nanorods demonstrate an eleven-fold increase in response. Furthermore, when subjected to various gases (CH₄, H₂S, CO₂, H₂), a notable selectivity toward H₂S is observed. This study paves the way for the development of p-type semiconductor sensors with heightened selectivity and sensitivity towards H₂S, thus advancing the prospects of gas sensor technology.

• The korean journal of orthodontics
• /
• v.51 no.4
• /
• pp.270-281
• /
• 2021

Objective: The aim of this in vitro study was to evaluate the changes in friction between orthodontic brackets and archwires coated with aluminum oxide (Al₂O₃), titanium nitride (TiN), or chromium nitride (CrN). In addition, the resistance of the coatings to intraoral conditions was evaluated. Methods: Stainless steel canine brackets, 0.016-inch round nickel-titanium archwires, and 0.019 × 0.025-inch stainless steel archwires were coated with Al₂O₃, TiN, and CrN using radio frequency magnetron sputtering. The coated materials were examined using scanning electron microscopy, an X-ray diffractometer, atomic force microscopy, and surface profilometry. In addition, the samples were subjected to thermal cycling and in vitro brushing tests, and the effects of the simulated intraoral conditions on the coating structure were evaluated. Results: Coating of the metal bracket as well as nickel-titanium archwire with Al₂O₃ reduced the coefficients of friction (CoFs) for the bracket-archwire combination (p < 0.01). When the bracket and stainless steel archwire were coated with Al₂O₃ and TiN, the CoFs were significantly lower (0.207 and 0.372, respectively) than that recorded when this bracket-archwire combination was left uncoated (0.552; p < 0.01). The friction, thermal, and brushing tests did not deteriorate the overall quality of the Al₂O₃ coatings; however, some small areas of peeling were evident for the TiN coatings, whereas comparatively larger areas of peeling were observed for the CrN coatings. Conclusions: Our findings suggest that the CoFs for metal bracket-archwire combinations used in orthodontic treatment can be decreased by coating with Al₂O₃ and TiN thin films.