Showing papers by "Junsin Yi published in 2001"
TL;DR: Theoretical and experimental investigations were performed on a double layer anti-reflection (DLAR) coating of MgF 2 /CeO 2. as discussed by the authors investigated CeO 2 films as an AR layer because they have a proper refractive index of 2.46.
Abstract: Theoretical and experimental investigations were performed on a double layer anti-reflection (DLAR) coating of MgF 2 /CeO 2 . We investigated CeO 2 films as an AR layer because they have a proper refractive index of 2.46 and demonstrate the same lattice constant as the Si substrate. An optimized DLAR coating showed a reflectance value as low as 1.87% over wavelengths ranging from 0.4 to 1.1 μm. Buried contact solar cells (BCSC) were investigated using the following structure: MgF 2 /CeO 2 /Ag/Cu/Ni grid/n + emitter/p-type Si base/P + /Al. The BCSC efficiency under an illumination of 50 mW/cm 2 measured as high as 19.9% when employing DLAR coatings. MgF 2 /CeO 2 DLAR coatings on the BCSC cell contributed to an increase of the fill factor (from 71% to 75%) and the J sc (from 19.8 mA/cm 2 to 22.6 mA/cm 2 ).
25 citations
TL;DR: LiNbO3 metal ferroelectric semiconductor (MFS) capacitors with low interface trap density, a low interaction with Si substrate, and a large remanent polarization were investigated in this paper.
Abstract: We investigated LiNbO3 metal ferroelectric semiconductor (MFS) capacitors because of the following advantages: a low interface trap density, a low interaction with Si substrate, and a large remanent polarization. Ferroelectric LiNbO3 thin films were grown directly on p-type Si(100) substrates for metal ferroelectric semiconductor field effect transistor (MFSFET) applications. Low temperature film growth and post rapid thermal anneal (RTA) treatments improved the leakage current of films while keeping other properties almost the same as high substrate temperature grown samples. We reduced the leakage current density of LiNbO3 films from 10−5 A/cm2 to 10−7 A/cm2 with RTA treatment. LiNbO3 MFS capacitors exhibited a breakdown electric field of greater than 500 kV/cm. RTA treatment above 600°C converted LiNbO3 films from amorphous to polycrystalline states with ( 0 1 2 ), ( 0 1 5 ), ( 0 2 2 ), and ( 0 2 3 ) planes. The polycrystalline LiNbO3 MFS capacitors illustrated the ferroelectric switching characteristics with a memory window ranging from 0.6 to 1.9 V. We obtained a remanent polarization of 2.74 μC/cm2 and a coercive field of 170 kV/cm using the LiNbO3 MFS capacitors.
22 citations
TL;DR: In this article, an electron-stimulated modification of a semiconductor-dielectric interface of an ITO/SiO2/InAs structure has been proposed to improve electrophysical parameters.
2 citations
TL;DR: In this article, a feasibility of Y2O3 films as a buffer layer of MFIS (metal ferroelectric insulator semiconductor) type capacitors was investigated and two-step process of low temperature film growth and subsequent RTA treatment.
Abstract: In this paper we investigated a feasibility of Y2O3 films as a buffer layer of MFIS (metal ferroelectric insulator semiconductor) type capacitor. Buffer layers were prepared by two-step process of a low temperature film growth and subsequent RTA treatment. Investigated parameters are given as substrate temperature, O2 partial pressure, post-annealing temperature, and suppression method of interfacial SiO2layer generation. By employing an ultra thin Y pre-metal layer, unwanted SiO2 layer generation was successfully suppressed at an interface between the buffer layer and Si substrate. By using two-step process, we improved the leakage current density of Y2O3 films by 2 orders and the Dit as low as 8.72×1010 cm−2eV−1. For a substrate temperature above 400°C and O2 partial pressure of 20%, we observed cubic Y2O3 phase domination in XRD spectra. We achieved 1.75% lattice mismatch between Y2O3 film and silicon substrate. Y2O3 buffer layer for a single transistor FRAM exhibited optimal properties when it was grown at 400°C with 20% O2 partial pressure then RTA treatment at 900°C in oxygen ambient.
TL;DR: In this paper, a novel structure of polycrystalline silicon (poly-Si) solar cell for terrestrial applications was proposed, where a 10μm deep trench along grain boundaries and randomly textured grain surface with pyramid structure were observed.
Abstract: This paper deals with a novel structure of polycrystalline silicon (poly-Si) solar cell for terrestrial applications. Grain boundary (GB) in poly-Si degrades a conversion efficiency of poly-Si solar cell. To reduce the GB side-effect, we investigated various parameters such as the preferential GB etch, etchtime, ITO electrode, heat treatment, and emitter layer effect. Among various preferential etchants such as Sirtl, Yang, Secco, and Schimmel, a Schimmel etchant illustrated an excellent preferential etching property. We observed a 10μm deep trench along grain boundaries and randomly textured grain surface with pyramid structure. We used rf magnetron sputter grown tin doped indium oxide (ITO) film as a top contact metal. ITO films showed a resistivity of 1.14 ×10 -4 Ω-cm and transmittance of 90.5% for the wavelength of 594 nm. ITO films served as a top electrode as well as an effective AR coating layer. ITO film properties were strongly influenced by the preparation temperatures. Substrate temperature of 400 o C gave the highest conversion efficiency of poly-Si solar cell. With well-fabricated poly-Si solar cells, we were able to achieve conversion efficiency as high as 16% at the input power of 20 mW/cm 2 .
01 Oct 2001
TL;DR: In this article, the structural and electrical properties of the Ba ( ) (BZT thin films with a mole fraction of x=0.2 and thickness 150 nm for the application in MLCC (Multilayer Ceramic Capacitor).
Abstract: We investigated the structural and electrical properties of the Ba ( ) (BZT thin films with a mole fraction of x=0.2 and thickness 150 nm for the application in MLCC (Multilayer Ceramic Capacitor). BZT films were prepared on /Si substrate at various substrate temperatures by the RF-magnetron sputtering system. When the substrate temperature was above , we could obtain multi-crystalline BZT films oriented at (110), (111), and (200) directions. The crystallization of the film and high dielectric constant were observed with the increase of substrate temperature. Capacitance of the film deposited at high temperature is more sensitive to the applied voltage than that of the film deposited at low temperature. This paper reports surface morphology, dielectric constant, dissipation factor, and C-V characteristics for BZT films deposited at three different temperatures. The BZT film deposited at 40 shows stable electrical properties but a little small dielectric constant for MLCC application.
TL;DR: In this article, the dielectric constants and losses of ZrTiO 4 thin films deposited by DC magnetron reactive sputtering were investigated, and the paraelectric properties were measured in the 100kHz range and compared with an equivalent circuit model.
Abstract: The dielectric constants and dielectric losses of ZrTiO 4 thin films deposited by DC magnetron reactive sputtering were investigated. The paraelectric properties were measured in the 100kHz range and compared with an equivalent circuit model. As the deposition temperature increased (up to 600°C), the dielectric losses (tanσ) decreased (down to 0.017±0.007), while the dielectric constants (e) were in the range of 35±7. Post annealing at 800°C in oxygen for 2h reduced tanσ down to 0.005±0.001, higher than those of well-sintered bulk ZrTiO 4 .