• Proceedings of the Korean Vacuum Society Conference
• /
• 2016.02a
• /
• pp.416-416
• /
• 2016

Organic-inorganic metal halide perovskite solar cells have received attention because it has a number of advantages with excellent light harvesting, high carrier mobility, and facile solution processability and also recorded recently power conversion efficiency (PCEs) of over 20%. The major issue on perovskite solar cells have been reached the limit of small area laboratory scale devices produced using fabrication techniques such as spin coating and physical vapor deposition which are incompatible with low-cost and large area fabrication of perovskite solar cells using printing and coating techniques. To solution these problems, we have investigated the feasibility of achieving fully printable perovskite solar cells by the blade-coating technique. The blade-coating fabrication has been widely used to fabricate organic solar cells (OSCs) and is proven to be a simple, environment-friendly, and low-cost method for the solution-processed photovoltaic. Moreover, the film morphology control in the blade-coating method is much easier than the spray coating and roll-to-roll printing; high-quality photoactive layers with controllable thickness can be performed by using a precisely polished blade with low surface roughness and coating gap control between blade and coating substrate[1]. In order to fabricate perovskite devices with good efficiency, one of the main factors in printed electronic processing is the fabrication of thin films with controlled morphology, high surface coverage and minimum pinholes for high performance, printed thin film perovskite solar cells. Charge dissociation efficiency, charge transport and diffusion length of charge species are dependent on the crystallinity of the film [2]. We fabricated the printed perovskite solar cells with large area and flexible by the bar-coating. The morphology of printed film could be closely related with the condition of the bar-coating technique such as coating speed, concentration and amount of solution, drying condition, and suitable film thickness was also studied by using the optical analysis with SEM. Electrical performance of printed devices is gives hysteresis and efficiency distribution.

• Proceedings of the Korean Vacuum Society Conference
• /
• 2012.02a
• /
• pp.346-346
• /
• 2012

We investigated electrical and optical properties and chemical states of amorphous In-Ga-Zn-O (a-IGZO) thin films deposited at different substrate temperatures (from room temperature to $300^{\circ}C$). a-IGZO thin films were fabricated by radio frequency magnetron sputtering using $In_2O_3$ : $Ga_2O_3$ : ZnO = 1 : 1 : 1 target, and their electrical and optical properties and chemical states were investigated by Hall-measurement, UV-visible spectroscopy and x-ray photoelectron spectroscopy (XPS), respectively. The data showed that as substrate temperature increased, carrier concentration increased, but mobility, conductivity, transmittance in the shorter wavelength region (>350 nm), and the Tauc-plot-estimated optical bandgap decreased. XPS data indicated that the intensity of In 3d peak compared to Ga 3d peak increased but the intensity of Zn 3d peak compared to Ga 3d decreased, and that, from the deconvoluted O 1s peak, defects or oxygen vacancies and non-quaternary contents increased as the temperature increased. The relative intensity changes of the In, Zn, and O 1s sub-component are suggested to explain the changes in electrical and optical properties.

• Korean Journal of Materials Research
• /
• v.25 no.4
• /
• pp.177-182
• /
• 2015

Sb-doped $SnO_2$(ATO) thin films were prepared using electrospinning. To investigate the optimum properties of the electrospun ATO thin films, the deposition numbers of the ATO nanofibers(NFs) were controlled to levels of 1, 2, 4, and 6. Together with the different levels of deposition number, the structural, chemical, morphological, electrical, and optical properties of the nanofibers were investigated. As the deposition number of the ATO NFs increased, the thickness of the ATO thin films increased and the film surfaces were gradually densified, which affected the electrical properties of the ATO thin films. 6 levels of the ATO thin film exhibited superior electrical properties due to the improved carrier concentration and Hall mobility resulting from the increased thickness and surface densification. Also, the thickness of the samples had an effect on the optical properties of the ATO thin films. The ATO thin films with 6 deposited levels displayed the lowest transmittance and highest haze. Therefore, the figure of merit(FOM) considering the electrical and optical properties showed the best value for ATO thin films with 4 deposited levels.

• Proceedings of the Korean Vacuum Society Conference
• /
• 2013.02a
• /
• pp.315-315
• /
• 2013

We report the electronic structure modification in the swift heavy ion (SHI) irradiated N-doped ZnO thin films prepared by RF sputtering from ZnO target in different ratio of Ar/$N_2$ gas mixture using highly pure $N_2$ gas. The different N-ZnO thin lms were then irradiated with 120 MeV Ag ion beam with different doses ranging from $1{\times}10^{11}$ to $5{\times}10^{12}$ ions/$cm^2$ and characterized by XRD and near edge X-ray absorption ne structure (NEXAFS) at N and O K-edges. The NEXAFS measurements provide direct evidence of O 2p and Zn 3d orbital hybridization and also the bonding of N ions with Zn and O ions. The minimum value of resistivity of $790{\Omega}cm$, a Hall mobility of $22cm^2V^-1s^-1$ and the carrier concentration of $3.6{\times}10^{14}cm^{-3}$ were yielded at 75% $N_2$. X-ray diffraction (XRD) measurements revealed that N-doped ZnO films had the preferential orientation of (002) plane for all samples, while crystallinity start decreasing at 32.5% $N_2$. The average crystallite size varies from 5.7 to 8.2 nm for 75% and then decreases to 7.8 nm for 80% $Ar:N_2$ ratio.

• Journal of the Korean Ceramic Society
• /
• v.48 no.4
• /
• pp.328-333
• /
• 2011

The influence of Al-doped ZnO (AZO) thin films degraded under high temperature and damp heat on the performance deterioration of Cu(In,Ga)$Se_2$ (CIGS) solar cells was investigated. CIGS solar cells with AZO/CdS/CIGS/Mo structure were prepared on glass substrate and exposed to high temperature ($85^{\circ}C$) and damp heat ($85^{\circ}C$/85% RH) for 1000 h. As-prepared CIGS solar cells had 64.91% in fill factor (FF) and 12.04% in conversion efficiency. After exposed to high temperature, CIGS solar cell had 59.14% in FF and 9.78% in efficiency, while after exposed to damp heat, it had 54.00% in FF and 8.78% in efficiency. AZO thin films in the deteriorated CIGS solar cells showed increases in resistivity up to 3.1 times and 4.4 times compared to their initial resistivity after 1000 h of high temperature and damp heat exposure, respectively. These results can be explained by the decreases in carrier concentration and mobility due to diffusion or adsorption of oxygen and moisture in AZO thin films. It can be inferred that decreases in FF and conversion efficiency were caused by an increase in series resistance, which resulted from an increase in resistivity of AZO thin films degraded under high temperature and damp heat.

• Journal of the Korean institute of surface engineering
• /
• v.49 no.1
• /
• pp.92-97
• /
• 2016

The plasma has been used in various industrial fields of semiconductors, displays, transparent electrode and so on. Plasma diagnostics is critical to the uniform process and the product. We use the electron temperature of the various plasma parameters for the diagnosis of plasma. Generally, the range of the electron temperature which is used in a semiconductor process used the range of 1 eV to 10 eV. The difference of electron temperature of 0.5 eV has a influence in plasma process. The electron temperature can be measured by the electrical method and the optical method. Measurement of electron temperature for various gas flow rates was performed in DC-magnetron sputter and Inductively Coupled Plasma. The physical properties of the thin film were also determined by changing electron temperatures. The transmittance was measured using the integrating sphere, and wavelength range was measured at 300 ~ 1100 nm. We obtain the thin film of the mobility, resistivity and carrier concentration using the hall measurement system. As to the electron temperature increase, optical and electrical properties decrease. We determine it was influenced by the oxygen flow ratio and plasma.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.28 no.12
• /
• pp.852-856
• /
• 2015

In this study, we investigate the effect of high-energy ball milling on thermoelectric transport properties in double-filled $CoSb_3$ skutterudite ($In_{0.2}Yb_{0.1}Co_4Sb_{12}$). $In_{0.2}Yb_{0.1}Co_4Sb_{12}$ powders are milled using high-energy ball milling for different periods of time (0, 5, 10, and 20 min), and the milled powders are consolidated into bulk samples by spark plasma sintering. Microstructure analysis shows that the high-energy ball milled bulk samples are composed of nano- and micro-grains. Because the filling fractions are reduced in the bulk samples due to the kinetic energy of the high-energy ball milling, the carrier concentration of the bulk samples decreases with the ball milling time. Furthermore, the mobility of the bulk samples also decreases with the ball milling time due to enhanced grain boundary scattering of electrons. Reduction of electrical conductivity by ball milling has a decisive effect on thermoelectric transport in the bulk samples, power factor decreases with the ball milling time.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.20 no.7
• /
• pp.594-599
• /
• 2007

[ $CulnS_2$ ] thin films were synthesized by sulfurization of Cu/In Stacked elemental layer deposited onto glass Substrates by vacuum furnace annealing at temperature $200^{\circ}C$. And structural and electrical properties were measured in order to certify optimum conditions for growth of the ternary compound semiconductor $CuInS_2$ thin films with non-stoichiometry composition. $CuInS_2$ thin film was well made at the annealed $200^{\circ}C$ of SLG/Cu/In/S stacked elemental layer which was prepared by thermal evaporator, and chemical composition of the thin film was analyzed nearly as the proportion of 1 : 1 : 2. Physical properties of the thin film were investigated at various fabrication conditions substrate temperature, annealing and temperature, annealing time by XRD, FE-SEM and Hall measurement system. The compositional deviations from the ideal chemical formula for $200^{\circ}C$ material can be conveniently described by non-molecularity$({\Delta}x=[Cu/In]-1)$ and non-stoichiometry $({\Delta}y=[{2S/(Cu+3In)}-1])$. The variation of ${\Delta}x$ would lead to the formation of equal number of donor and accepters and the films would behave like a compensated material. The ${\Delta}y$ parameter is related to the electronic defects and would determine the type of the majority charge carriers. Films with ${\Delta}y>0$ would behave as p-type material while ${\Delta}y<0$ would show n-type conductivity. At the sane time, carrier concentration, hall mobility and resistivity of the thin films was $9.10568{\times}10^{17}cm^{-3},\;312.502cm^2/V{\cdot}s\;and\;2.36{\times}10^{-2}\;{\Omega}{\cdot}cm$, respectively.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.24 no.7
• /
• pp.568-573
• /
• 2011

AZO (Al doped ZnO) thin films were deposited on the quartz substrates with thickness variation from 25 to 300 nm by using PLD (pulsed laser deposition). XRD (x-ray diffractometer), SPM (scanning probe microscopy), Hall effect measurement and uv-visible spectrophotometer were employed to investigate the structural, morphological, electrical and optical properties of the thin films. XRD results demonstrated that films were preferrentially oriented along the c-axis and crystallinity of film was improved with increase of film thickness. As for the surface morphologies, the mean diameter and root mean square of grains were increased as the film thickness was increased. When the film thickness was 200 nm, the lowest resistivity of $4.25{\times}10^{-4}\;{\Omega}cm$ obtained with carrier concentration of $6.84{\times}10^{20}\;cm^{-3}$ and mobility of $21.4\;cm^2/V{\cdot}S$. All samples showed more than 80% of transmittance in the visible range. Upon these results, it is found that the samples thickness can affect their structural, morphological, optical and electrical properties. This study suggests that the resistivity can be improved by controlling film thickness.

• Proceedings of the Korean Vacuum Society Conference
• /
• 2011.02a
• /
• pp.87-87
• /
• 2011

Oxide semiconductors are attractive materials for thin-film electronics and optoelectronics due to compatibility with synthesis on large-area, glass and flexible substrate. However, development of thin-film electronics has been hampered by the limited number of semiconducting oxides that are p-type. We report on the effect of the oxygen partial pressure ratio in the gas mixture on the electrical and optical properties of spinel Mg:$ZnCo_2O_4$ thin films deposited at room temperature using RF sputtering, that exhibit p-type conduction. The thin-films are deposited at room temperature in a background of oxygen using a polycrystalline Mg:$ZnCo_2O_4$ ablation target. The p-type conduction is confirmed by positive Seebeck coefficient and positive Hall coefficient. The electrical resistivity and carrier concentration in on dependent Mg:$ZnCo_2O_4$ thin films were found to be dependent on the oxygen partial pressure ratio. As a result, it is revealed that the Mg:$ZnCo_2O_4$ thin-films were greatly influenced on the electrical and optical properties by the oxygen partial pressure condition. The visible region of the spectrum of 36~85%, and hole mobility of 1.1~3.7 $cm^2$/Vs, were obtained.