• Current Photovoltaic Research
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• v.5 no.2
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• pp.55-58
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• 2017

We investigated the influences of dielectric thin film coating on the optical characteristics of c-Si wafers with nanocone (NC) arrays using finite-difference time-domain (FDTD) simulations. Dielectric thin films on high-refractive-index surface can lower optical reflection and reflection dips appear at the wavelengths where destructive interference occurs. The optical reflection of the NC arrays was lower than that of the dielectric-coated planar wafer in broad wavelength range. Remarkable antireflection effects of the NC array could be attributed to beneficial roles of the NCs, including the graded refractive index, multiple reflection, diffraction, and Mie resonance. Dielectric thin films modified the optical reflection spectra of the NC arrays, which could not be explained by the interference alone. The optical properties of the dielectric-coated NC arrays were determined by the inherent optical characteristics of the NC arrays.

• Journal of Surface Science and Engineering
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• v.26 no.1
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• pp.3-9
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• 1993

Chemical vapor deposited tungsten films were formed in a cold wall reactor at pressures higher (10~120torr) than those conventionally employed (<1torr). SiH4, in addition to H2, was used as the reduction gas. The effects of pressure and reaction temperature on the deposition rate and morphology of the films were ex-amined under the above conditions. No encroachment or silicon consumption was observed in the tungsten de-posited specimens. A high deposition rate of tungsten and a good step coverage of the deposited films were ob-tained at 40~80 torr and at a temperature range of $360~380^{\circ}C$. The surface roughness and the resistivity of the deposited film increased with pressure. The deposition rate of tungsten increased with the total pressure in the reaction chamber when the pressure was below 40 torr, whereas it decreased when the total pressure ex-ceedeed 40 torr. The deposition rate also showed a maximum value at $360^{\circ}C$ regardless of the gas pressure in the chamber. The results suggest that the deposition mechanism varies with pressure and temperature, the surface reac-tion determines the overall reaction rate and (2) at higher pressures(>40 torr) or temperatures(>36$0^{\circ}C$), the rate is controlled by the dtransportation rate of reactive gas molecules. It was shown from XRD analysis that WSi2 and metastable $\beta$-W were also formed in addition to W by reactions between WF6 and SiH4.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.11a
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• pp.185-185
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• 2009

The aligned liquid crystals (LCs) display on SiNx thin films using ion-beam (IB) irradiation was studied with controllability ofpretilt angle depending on incident energies of the IB. Plasma-enhanced chemical vapor deposition (PECVD) was used to orient the LCs on SiNx alignment films. The LCs alignment property for the SiNx thin films were observed to verify the practical application potential (figure1). A good LCs alignment of vertical alignment LCs cells on SiNx thin film surfaces irradiated with incident IB energy of 1800eV was achieved. Also, a good LC alignment by the IB irradiation on the SiNx thin film surface was observed at an annealing temperature of $180^{\circ}C$. However, the alignment defects of the nematic liquid crystal was observed at an annealing temperature above $230^{\circ}C$. The atomic force microscopy (AFM) images of LCs on SiNx thin film surfaces irradiated with IB energy was used for the surface analysis.

• Journal of the Korean Vacuum Society
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• v.9 no.3
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• pp.249-253
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• 2000

We have analyzed electrical characteristics of the amorphous $MgTiO_3$thin films deposited by pulsed laser deposition (PLD) technique with the temperature of 400~$500^{\circ}C$. The electrical characteristics of $MgTiO_3$films heavily depend on the deposition temperature. We speculate that the density of anomalous positive charge (APC) substantially increases as the deposition temperature lowers, causing the HF C-V curves shift to the direction of the negative gate voltage. We further observed that both the degree of C-V shift as a function of the deposition temperature and the density of APC were minimized by the use of $SiO_2$with thickness of approximately 100 $\AA$ between $MgTiO_3$films and the Si substrate.

• Journal of the Korean Ceramic Society
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• v.48 no.6
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• pp.621-624
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• 2011

In order to deposit a homogeneous and uniform ${\beta}$-SiC films by chemical vapor deposition, we constructed the phase-diagram of ${\beta}$-SiC over graphite and silicon via computational thermodynamic calculation considering pressure(P), temperature(T) and gas composition(C) as variables in $C_3H_8-SiCl_4-H_2$ system. During the calculation, the ratio of Cl/Si and C/Si is maintained to be 4 and 1, respectively, and H/Si ratio is varied from 2.67 to 15,000. The P-T-C diagram showed very steep phase boundary between SiC+C and SiC region perpendicular to H/Si axis and also showed SiC+Si region with very large H/Si value of ~6700. The diagram can be applied not only to the prediction of the deposited phase composition but to compositional variation due to the temperature distribution in the reactor. The P-T-C diagram could provide the better understanding of chemical vapor deposition of silicon carbide.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.11a
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• pp.442-443
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• 2007

Al-N co-doped ZnO films were fabricated on n-Si (100) and homo-buffer layers in the mixture of oxygen and nitrogen at $450^{\circ}C$ by magnetron sputtering. Target was ZnO ceramic mixed with $2wt%Al_2O_3$. XRD spectra show that as-grown and $600^{\circ}C$ annealed films are prolonged along crystal c-axis. However they are not prolonged in (001) plane vertical to c-axix. The films annealed at $800^{\circ}C$ are not prolonged in any directions. Codoping makes ZnO films unidirectional variation. XPS show that Al content hardly varies and N escapes with increasing annealing temperature from $600^{\circ}C\;to\;800^{\circ}C$. The electric properties of as-grown films were tested by Hall Effect with Van der Pauw configuration show some of them to be p-type conduction.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1997.11a
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• pp.173-176
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• 1997

The III-V nitride semiconductor InN thin films which have the direct bandgap in visible light wavelength region have been deposited on Si(100) substrates and AIN/Si(100) substrates by rf reactive sputtering. InN thin films have been investigated on the structural, and electrical properties according to the sputtering parameters such as total pressure, rf power, and substrate temperature. It is found that optimal conditions required for fabricating InN thin films with high crystal Quality, low carrier concentration, high Hall mobility are total pressure 5mTorr, rf power 60W, substrate temperature 6$0^{\circ}C$ . InN thin films deposited on the AIN(60min.)/Si(100) substrates arid AIN(120min.)/Si(100) substrates showed remarkably high crystal quality and electrical properties. It is known that AIN buffer layer is to decrease free energy at interface between InN film and Si substrate, and then promoting lateral growth of InN films.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.11a
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• pp.124-124
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• 2009

We observed the changes of crystal structure of Rubrene (5,6,11,12-tetraphenylnaphthacene) polycrystal thin films at various in situ substrate temperature and process by scanning electron microscope(SEM), x-ray diffraction (XRD) and near-field microwave microprobe (NFMM). Amorphous rubrene thin film was initially obtained on 200 nm thick $SiO_2/Si$ substrate at 35 $^{\circ}C$ in a vacuum evaporation but in situ long time postannealing at the temperature 80 $^{\circ}C$ transformed the amorphous phase into crystalline. Four heating conditions are followed : (a) preheating (b) annealing (c) preheating, annealing (d) preheating, cooling(35 $^{\circ}C$), annealing. We have obtained the largest polycrystal disk in sample (c). But the highest crytallity and conductivity of the rubrene thin films were obtained in sample (d).

• The Korean Journal of Ceramics
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• v.3 no.3
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• pp.173-176
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• 1997

Direct metal ion beam deposition is considered to be a whole new thin film deposition technique. Unlike other conventional thin film deposition processes, the individual deposition particles carry its own ion beam energies which are directly coupled for the formation of this films. Due to the nature of ion beams, the energies can be controlled precisely and eventually can be tuned for optimizing the process. SKION's negative C- ion beam source is used to investigate the initial nucleation mechanism and growth. Strong C- ion beam energy dependence has been observed. Complete phase control of sp3 and sp3, control of the C/SiC/Si interface layer, control of crystalline and amorphous mode growth, and optimization of the physical properties for corresponding applications can be achieved.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2000.07a
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• pp.897-900
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• 2000

Annealing dependencies of the fatigue properties of SrBi$_2$Ta$_2$$O_{9}$ thin films were observed as function of substrate temperature(400-50$0^{\circ}C$) by the rf magnetron sputtering method. With increasing annealing temperature from $600^{\circ}C$ to 85$0^{\circ}C$, flourite phase was crystalized to $650^{\circ}C$ and Bi-layered perovskite phase was crystalized above $700^{\circ}C$. The fatigue characteristics of SBT thin films deposited on Pt/TiO$_2$/SiO$_2$/Si substrate did not change up to 101o switching cycles.s.