• Transactions of the Korean hydrogen and new energy society
• /
• v.29 no.5
• /
• pp.434-441
• /
• 2018

The pore size of nickel (Ni) bottom electrode layer (BEL) for low-temperature solid oxide fuel cells embedded with ultrathin-film electrolyte was controlled by changing the substrate surface morphology and deposition process parameters. For ~150-nm-thick Ni BEL, the upper side of an anodic aluminum oxide (AAO) substrate with ~65-nm-sized pores provided ~1.7 times smaller pore size than the lower side of the AAO substrate. For ~100-nm-thick Ni BEL, the AAO substrate with ~45-nm-sized pores provided ~2.6 times smaller pore size than the AAO substrate with ~95-nm-sized pores, and the deposition pressure of ~4 mTorr provided ~1.3 times smaller pore size than that of ~48 mTorr. On the AAO substrate with ~65-nm-sized pores, the Ni BEL deposited for 400 seconds had ~2 times smaller pore size than the Ni BEL deposited for 100 seconds.

• Ceramist
• /
• v.22 no.2
• /
• pp.146-169
• /
• 2019

To overcome the theoretical efficiency of single-junction solar cells (> 30 %), tandem solar cells (or multi-junction solar cells) is considered as a strong nominee because of their excellent light utilization. Organic-inorganic halide perovskite has been regarded as a promising candidate material for next-generation tandem solar cell due to not only their excellent optoelectronic properties but also their bandgap-tune-ability and low-temperature process-possibility. As a result, they have been adopted either as a wide-bandgap top cell combined with narrow-bandgap silicon or CuIn_xGa_(1-x)Se₂ bottom cells or for all-perovskite tandem solar cells using narrow- and wide-bandgap perovskites. To successfully transition perovskite materials from for single junction to tandem, substantial efforts need to focus on fabricating the high quality wide- and narrow-bandgap perovskite materials and semi-transparent electrode/recombination layer. In this paper, we present an overview of the current research and our outlook regarding perovskite-based tandem solar technology. Several key challenges discussed are: 1) a wide-bandgap perovskite for top-cell in multi-junction tandem solar cells; 2) a narrow-bandgap perovskite for bottom-cell in all-perovskite tandem solar cells, and 3) suitable semi-transparent conducting layer for efficient electrode or recombination layer in tandem solar cells.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2007.06a
• /
• pp.202-203
• /
• 2007

Ferroelectric SBT($SrBi_2Ta_2O_9$) thin films were deposited on Pt/Ti/$SiO_2$/Si substrate using R.F. magnetron sputtering method. The ferroelectric and electric characteristics were investigated with various post-annealing of Pt at $200{\sim}600^{\circ}C$. Compared with SBT thin film which had not post-annealed, the electrical properties and crystallizations of the SBT thin films were relatively improved by the post-annealing of Pt bottom electrode. The crystallization were characterized by X-ray diffraction (XRD). The electrical properties characteristics were observed by HP 4192A and precision LC.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.33 no.6
• /
• pp.433-438
• /
• 2020

To enhance the tunneling electroresistance (TER) ratio of a ferroelectric tunnel junction (FTJ) device using Al-doped HfO₂ thin films, a thin insulating layer was prepared on a TiN bottom electrode, for which TiN was preliminarily treated at various temperatures in O₂ ambient. The composition and thickness of the inserted insulating layer were optimized at 600℃ and 50 Torr, and the FTJ showed a high TER ratio of 430. During the heat treatments, a titanium oxide layer formed on the surface of TiN, that suppressed oxygen vacancy generation in the ferroelectric thin film. It was found that the fabricated FTJ device exhibits two distinct resistance states with higher tunneling currents by properly heat-treating the TiN bottom electrode of the HfO₂-based FTJ devices in O₂ ambient.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2003.11a
• /
• pp.352-355
• /
• 2003

[ $Bi_{3.25}La_{0.75}Ti_3O_{12}$ ] (BLT) thin films were prepared by using metal organic decomposition method onto the LaNiO3 (LNO) bottom electrode. Both the structure and morphology of the films were analyzed by x-ray diffraction (XRD) and atomic force microscope (AFM). Even at low temperatures ranging from 450 to $650^{\circ}C$, the BLT thin films were successfully deposited on LNO bottom electrode and exhibited (117) orientation. The BLT thin films annealed as low as $600^{\circ}C$ showed excellent ferroelectricity, higher remanent polarization and no significant degradation of switching charge at least up to $5{\times}10^9$ switching cycles at a frequency of 100 kHz and 5 V. For the annealing temperature of $600^{\circ}C$, the remanent polarization $P_r$ and coercive field were $23.5\;{\mu}C/cm^2$ and 120 kV/cm, respectively.

• Proceedings of the Korea Association of Crystal Growth Conference
• /
• 1998.06a
• /
• pp.57-60
• /
• 1998

Lean zirconate titanate (PZT) is an attractive material for the memory device applications. We have investigated Pt and{{{{ { RuO}_{2 } }}}} as a botton electrode for a device application of PZT thin film. The bottom electrodes were prepared by using an RF magnetron sputtering method. The substrate temperature influenced the resistivity of Pt and {{{{ { RuO}_{2 } }}}} a s well as the film crystal structure. XRD examination shows that a preferred(111) orientations for the substrate temperature of 30$0^{\circ}C$. From the XRD and AFM results, we recommend the substrate temperature of 30$0^{\circ}C$ for the bottom electrode growth. We investigated and anneal temperature effect because Perovskite PZT structure is recommended for the memory device applications and the structural transformation is occurred only after and elevated heat treatment. As post anneal temperature was increased from RT to $700^{\circ}C$, the resistivity of Rt and {{{{ { RuO}_{2 } }}}} w as decreased. Surface morphology was observed by AFM as a function of post anneal temperature.

• Journal of the Korean Institute of Telematics and Electronics A
• /
• v.32A no.7
• /
• pp.77-84
• /
• 1995

We studied the effects of the Zr/Ti ration and the bottom electrode (Pt or ITO) on the electrical properties of PZT thin films prepared by sol-gel method. Their permittivities and tagent losses with the variation of frequencies were measured by the LCR meter and their maximum polarizations, remanent polarizations, and coercive fields were obtained from the hysteresis loops measured by the Sawyer-Tower circuit. For the PZT thin film of the Zr/Ti ration of 53/47, permittivity at 10kHz, coercive field, maximum and remanent polarizations ere measured as 952, 20.7kV/cm, 10.43${\mu}C/cm^{2}$ and 4.3${\mu}C/cm^{2}$, respectively. For the film of the Zr/Ti ration of 25/75, coercive field, maximum and remanent polarizations were measured as 33.12kV/cm, 5.59${\mu}C/cm^{2}$ and 1.5${\mu}C/cm^{2}$, respectively. For the film of the Zr/Ti ratio of 75/25, they were measured as 23.8kV/cm, 7.45${\mu}C/cm^{2}$, and 3.5${\mu}C/cm^{2}$, repectively. Our investigation into the effects of the lower electrode on the electrical properties of PZT films showed the following results. The permittivities of the PZT films deposited on the ITO electrode decreased more quickly than those of the PZT films on the Pt electrode. The tangent losses of the former films increased more quickly than those of the latter. These may be due to the degradation of the quality of the interface between the electrode and the film, which results from the diffusion of Pb. It is also noticeable that permittivities and tangent losses of the PZT films deposited on the ITO electrode varied differently with the Zr/Ti ratio. This may indicate that the quality of the interface between the electrode and the film changes with the Zr/Ti ration of the PZT film.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.11 no.2
• /
• pp.344-348
• /
• 2007

In this paper, we propose the electrode of the Patterned Vertical Aligned (PVA) cell [1] for high transmittance. We use the 'TechWiz LCD' for calculation of the director configuration and optical characteristics to ensure the results of the proposed electrode structure. In general, the transmittance of the PVA cell depends on the shape of the electrode and cell gap. In this work the width of gate line and data line of the improved electrode design is set to be equal to that of the PVA conventional. Instead, we modified the shape of the top and bottom electrode on order to decrease the area of the defect. For verification, we compared the calculated optical transmittance of the PVA cell with the proposed electrode structure to the conventional PVA cell . As a result, we can confirm that the optical loss due to the variation of the retardation the LC cell around electrode can be definitely decreased by the proposed electrode.

• Korean Journal of Materials Research
• /
• v.11 no.8
• /
• pp.671-678
• /
• 2001

All solid-state thin film micro supercapacitor, which consists of $RuO_2$/LiPON/$RuO_2$ multi layer structure, was fabricated on Pt/Ti/Si substrate using a $RuO_2$ electrode. Bottom $RuO_2$ electrode was grown by dc reactive sputtering system with increasing $O_2/[Ar+O_2]$ ratio at room temperature, and a LiPON electrolyte film was subsequently deposited on the bottom $RuO_2$ electrode at pure nitrogen ambient by rf reactive sputtering system. Room temperature charge-discharge measurements based on a symmetric $RuO_2$/LiPON/$RuO_2$ structure clearly demonstrates the cyclibility dependence on the microstructure of the $RuO_2$ electrode. Using both glancing angle x-ray diffraction (GXRD) and transmission electron microscopy (TEM) analysis, it was found that the microstructure of the $RuO_2$ electrode was dependent on the oxygen flow ratio. In addition, x- ray photoelectron spectroscopy(XPS) examination shows that the Ru-O binding energy is affected by increasing oxygen flow ratio. Furthermore, TEM and AES depth profile analysis after cycling demonstrates that the interface layer formed by interfacial reaction between LiPON and $RuO_2$ act as a main factor in the degradation of the cyclibility of the thin film micro-supercapacitor.

• Journal of the Korean Ceramic Society
• /
• v.36 no.4
• /
• pp.403-409
• /
• 1999

The dielectric and pyroelectric properties of $Ba_{0.66}$$Sr_{0.38}$$TiO_{3}$(BST) thin films growtn on Pt/Ti/NON/Si us-ing RF magnetron sputtering have been investigated. With increasing the substrate temperature during de-position of the BST film in the range of 300-$600^{\circ}C$ the dielectric and pyroelectric constants of the film were increased due to improved crystallinity of the film. In addition the dependence of the microstructural and electrical properties of BST films onthe deposition temperature of the bottom Pt electrode was studied. The preferred orientation of the BST films as well as the microstructure of the Pt film was greatly in-fluenced by the deposition temperature of the bottom Pt electrode was studied. The preferred orientation of the BSt films as well as the microstructure of the Pt film was greatly in-fluenced by the deposition temperature of the bottom Pt electrodes. and thus so were the pyrolelectric pro-perties of the BST film. The highest value of pyroelectric coefficient at room temperature obtained in this work was $nCcm^{-2}K^{-1}$ which is much higher than those previously reported on other perovskite fer-roelectric thin films.