• Journal of Sensor Science and Technology
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• v.17 no.3
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• pp.203-209
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• 2008

Thick film formaldehyde (HCHO) gas sensors were fabricated by using $La_1_{-x}Sr_xMO_3$ (M= Fe, Co, Mn) ceramics. The powders of $La_1_{-x}Sr_xMO_3$ (M=Fe, Co, Mn) were synthesized by conventional solid-state reaction method. By using the $La_1_{-x}Sr_xMO_3$ (M=Fe, Co, Mn) paste, the thick-film formaldehyde sensors were prepared on the alumina substrate by silkscreen printing method. The experimental results revealed that $La_1_{-x}Sr_xMO_3$ (M= Fe, Co, Mn) ceramic powder has a perovskite structure and the thick-film sensor shows excellent gas-sensing characteristics to formaldehyde gas (sensitivity of $La_{0.8}Sr_{0.2}FeO_3$, S= 14.7 at operating temperature of $150^{\circ}C$ in 50 ppm HCHO ambient).

• Korean Journal of Materials Research
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• v.29 no.11
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• pp.715-719
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• 2019

Molybdenum is a low-resistivity transition metal that can be applied to silicon devices using Si-metal electrode structures and thin film solar cell electrodes. We investigate the deposition of metal Mo thin film by plasma-enhanced atomic layer deposition (PE-ALD). $Mo(CO)_6$ and $H_2$ plasma are used as precursor. $H_2$ plasma is induced between ALD cycles for reduction of $Mo(CO)_6$ and Mo film is deposited on Si substrate at $300^{\circ}C$. Through variation of PE-ALD conditions such as precursor pulse time, plasma pulse time and plasma power, we find that these conditions result in low resistivity. The resistivity is affected by Mo pulse time. We can find the reason through analyzing XPS data according to Mo pulse time. The thickness uniformity is affected by plasma power. The lowest resistivity is $176{\mu}{\Omega}{\cdot}cm$ at $Mo(CO)_6$ pulse time 3s. The thickness uniformity of metal Mo thin film deposited by PE-ALD shows a value of less than 3% below the plasma power of 200 W.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 2000.11a
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• pp.406-413
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• 2000

The friction and wear behaviors of Magnetron Sputtered MoS$_2$films were investigated by using a pin on disk type tester which was designed and manufactured for this experiment. The experiment was conducted by using silicon nitride (Si$_3$N$_4$) as a pin material and Magnetron Sputtered MoS$_2$on bearing steel (STB2) as a disk material, under operating conditions that include different surface roughness (Polishing specimen, Grinding specimen)(2types), linear sliding velocities in the range of 22, 44, 66mm/sec (3types), normal loads vary from 9.8N, 19.6N, 29.4N(3types), corresponding to contact pressures of 1.9∼2.7GPa and atmospheric conditions of high vacuum( 1.3${\times}$10$\^$-4/Pa), medium vacuum( 1.3${\times}$10$\^$-l/Pa), ambient air(10$\^$5/Pa)(3types). We investigated fracture mechanism in magnetron sputtered MoS$_2$films with Magnetron Sputtering method in each experiment.

• Korean Journal of Materials Research
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• v.11 no.11
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• pp.991-996
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• 2001

This study is the manufacture of solid lubricant oilless bearing using sintered parts. PTFE was as organic solid lubricant and $MoS_2$ as inorganic solid lubricant, and its characteristics were studied. Thickness of lubricant was suited 25~$100\mu\textrm{m}$ for lubricant characteristics. Curring temperature of MoS_2$ film was 12$0^{\circ}C$, 2 hours and that of PTFE film was $260^{\circ}C$, 20 minutes. The solid weight and solid volume of $MoS_2$ film was 51.7% and 27.4%, and that of PTFE was 44.9% and 24.3%. Chemical resistant of PTFE solid lubricant oilless bearing was excellent as salt test was 520hours, and usable temperature range was $-200~+280 ^{\circ}C$. Conduction of electricity can be increase by addition of graphite or $$\alpha$- PbO_2$. The electric conductivity was 100~180$\Omega$.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.50 no.12
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• pp.607-613
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• 2001

Molybdenum thin films were deposited on the soda lime glass(SLG) substrates by direct-current planar magnetron sputtering, with a sputtering power density of $4.44W/cm^2$. The working pressure was varied from 0.5 mtorr to 20 mtorr to gain a better understanding of the effect of sputtering pressure on the morphology and microstructure of the Mo film. Thin films of $CU(InGa)Se_2$ (CIGS) were deposited on the Mo-coated glass by three stage co-evaporation process. The highest efficiency device was obtained at the maximum value of the tensive stress. The morphology of Mo-coated films were examined by using scanning electron microscopy The film's microstructure, such as the preferred orientation, the full width at half-maximum(FWHM), and the residual intrinsic stress were examined by X-ray diffraction.

• Tribology and Lubricants
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• v.14 no.4
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• pp.72-78
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• 1998

In this work, the effects of binder materials on the tribological behavior were experimentally evaluated for air curable MoS$_2$bonded film lubricants. The binders tested were basically alkyd and acryl based resins, and also were modified by nitro-cellulose in various weight percentages. Effects on the binder ratio to solid lubricants and the molecular weight of binders were also investigated in all aspects of the tribological behavior. For the tests, LFW-1 and Falex tester were used to measure mainly the endurance life and load carrying capacity of bonded lubricants. Results showed that lubricants of methacrylic resin has the better performance than those of other resins, and also the properties of lubricants both of alkyd and acrylic resins could be improved by modification with nitro-cellulose. It was also shown that the optimum ratio of nitro-cellulose related closely to the binder material and the testing machine.

• Current Photovoltaic Research
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• v.5 no.1
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• pp.20-24
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• 2017

Recently, three-dimensional (3D) light harvesting structures are highly attracted because of their high light harvesting capacity and charge collection efficiencies. In this study, we have fabricated $Cu_2ZnSn(S_xSe_{1-x})_4$ based 3D thin film solar cells on PR patterned Molybdenum (Mo) substrates using photolithography technique. Specifically, Mo patterns were deposited on PR patterned Mo substrates by sputtering and the thin Cu-Zn-Sn stacked layer was deposited over this Mo patterns by sputtering technique. The stacked Zn-Sn-Cu precursor thin films were sulfo-selenized to form CZTSSe pattern. Finally, CZTSSe absorbers were coated with thin CdS layer using chemical bath deposition and ZnO window layer was deposited over CZTSSe/CdS using DC sputtering technique. Fabricated 3-D solar cells were characterized by X-ray diffraction (XRD), X-ray fluorescence (XRF) analysis, Field-emission scanning electron microscopy (FE-SEM) to study their structural, compositional and morphological properties, respectively. The 3% efficiency is achieved for this kind of solar cell. Further efforts will be carried out to improve the performance of solar cell through various optimizations.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.28A no.1
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• pp.85-90
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• 1991

MoSi$_2$ was formed by RTA (Rapid Thermal Annealing at 600-1200$^{\circ}C$) under Ar ambient from the Mo-Si mixture film which was deposited on single and poly-Si substrates. The MoSi$_2$ film was investigated by SEM, X-ray diffractometer, four-points probe and AES profile. It was found that the resistivity, the surface roughness, and the formation temperature of MoSi$_2$ were independent on the type of Si substrates. The formation of MoSi$_2$ started from 800$^{\circ}C$ and the phse transformation was completed at 1000$^{\circ}C$. The stable MoSi$_2$ with the resistivity of 74${\mu}{\Omega}$-cm was formed at 1200$^{\circ}C$.

• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.336-336
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• 2016

We have investigated magneto-transport properties in a MoS2 lateral spin-valve structures for different ferromagnetic CoFe electrode shapes and MoS2 channel lengths. For these devices, high quality and large-scale MoS2 thin films were synthesized through sulfurization of epitaxial MoO3 films and these sulfurized-MoO3 thin films properties are in good agreements with measurements on exfoliated MoS2 film. Magneto-transport measurements show a clear rectangular magnetoresistance signal of 0.16% and a spin polarization of 0.00012%. By using the one-dimensional spin diffusion equation, we extracted the spin diffusion length and coefficient, finding them to be 12 nm and $1.44{\times}10-3cm2/s$, respectively. These small values of magnetoresistance and spin polarization could be enhanced by appeasement of conductivity mismatch between the ferromagnet and semiconductor interface.

• Journal of Mechanical Science and Technology
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• v.16 no.9
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• pp.1065-1071
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• 2002

The friction and wear behaviors of magnetron sputtered MoS$_2$ films were investigated through the use of a pin and disk type tester. The experiments were performed for two kinds of specimens (ground (Ra 0.5 $\mu\textrm{m}$) and polished (Ra 0.01 $\mu\textrm{m}$) substrates) under the following operating condifions : linear sliding velocities in the range of 22～66 mm/s (3 types), normal loads varying from 9.8～29.4 N(3 types) and atmospheric conditions of air, medium and high vacuum (3types). Silicon nitride pin was used as the lower specimen and magnetron sputtered MoS$_2$ on bearing steel disk was used as the upper specimen. The results showed that low friction property of the MoS$_2$ films could be identified in high vacuum and the specific wear rate in air was much higher than that in medium and high vacuum due to severe oxidation. It was found that the main wear mechanism in air was oxidation whereas in high vacuum accumulation of plastic flow and adhesion, were the main causes of wear.