• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.17 no.5
• /
• pp.497-501
• /
• 2004

The crystal structure of the GaN film on the AIN buffer layer grown by R. F sputtering with different thickness has been studied using X-ray scattering and transmission electron microscopy(TEM). The interface roughness between the AIN buffer layer and the epitaxial GaN film, due to crossover from planar to island grains, produced edge dislocations. The strain, coming from lattice mismatch between the AIN buffer layer and the epitaxial GaN film, produced screw dislocations. The density of the edge and screw dislocation propagating from the interface between the GaN film and the AIN buffer layer affected the electric resistance of GaN film.

• ETRI Journal
• /
• v.37 no.6
• /
• pp.1129-1134
• /
• 2015

In this article, a study of a flower like nanostructured CdS buffer layer for improving the performance of a submicron-thick $CuIn_{1-x}Ga_xSe_2$ (CIGS) solar cell (SC) is presented. Both its synthesis and properties are discussed in detail. The surface reflectance of the device is dramatically decreased. SCs with flower like nanostructured CdS buffer layers enhance short-circuit current density, fill factor, and open-circuit voltage. These enhancements contribute to an increase in power conversion efficiency of about 55% on average compared to SCs that don't have a flower like nanostructured CdS buffer layer, despite them both having the same CIGS light absorbing layer.

• The Transactions of the Korean Institute of Electrical Engineers
• /
• v.44 no.2
• /
• pp.222-227
• /
• 1995

A new IGBT structure, which may suppress latch-up phenomena considerably, is proposed and verified by MEDICI simulation. The proposed structure employing the segmented $n^{+}$ buffer layer increases latch-up current capability due to suppression of the current flowing through the resistance of $p^{-}$ well, $R_{p}$, which is the main cause of latch-up phenomena without degradation of forward characteristics. The length of the $n^{+}$ buffer layer is investigated by considering the trade-off between the latch-up current capability and the forward voltage drop. The segmented $N^{+}$ buffer layer results in better latch-up immunity in comparison with the uniform buffer layer.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.23 no.1
• /
• pp.24-28
• /
• 2010

We have proposed an Buffer layer to improve the transmittance of ITO. Here, $SiO_2$ and $TiO_2$ were selected as the Buffer layer coating material. The structures of Buffer layer were designed in ITO/$SiO_2/TiO_2$/Glass and ITO/Glass/$TiO_2/SiO_2$. Then, these materials were deposited by ion-assisted deposition system. Transmittances of deposited ITO were 86.14 and 85.07%, respectively. These results show that the proposed structure has higher transmittance than the conventional ITO device.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2001.07a
• /
• pp.174-177
• /
• 2001

We have seen the effects of buffer layer in organic light-emitting diodes using poly(N-vinylcarbazole)(PVK). Polymer PVK buffer layer was made using spin casting techniques. Two different types of spin casting have been applied; static coating and dynamic coating. Two device structures were fabricated; one is ITO/TPD/Alq$_3$/Al as a reference, and the other is ITO/PVK/TPD/Alq$_3$/Al to see the effects of buffer layer in organic light-emitting diodes. Current-voltage characteristics and luminous efficiency were measured with a variation of spin-casting methods and rpm speeds. We have obtained an improvement of luminous efficiency by a factor of two and half when the PVK buffer layer is used.

• Journal of Fisheries and Marine Sciences Education
• /
• v.5 no.2
• /
• pp.128-137
• /
• 1993

This paper presents a new concept to reduce turbulent frictional drag by injecting micro-bubble into buffer layer of turbulent boundary layer on flat plate. The buffer layer of boundary was specified by minus velocity gradient of law of the wall. When the buffer layer region of turbulent boundary layer is filled with micro-bubble of air and viscous of the region is kept low, the velocity profile in the region should be changed substantially. Then the Reynolds stress in the buffer layer region becomes less, which guide to higher velocity gradient there. It results in reduction of velocity gradient at the viscous sublayer, which gives the reduction of shear stress at the wall.

• Journal of the Korean Society for Heat Treatment
• /
• v.28 no.6
• /
• pp.291-295
• /
• 2015

IGZO single layer and $IGZO/TiO_2$ bi-layered films were deposited on glass substrate at room temperature with radio frequency magnetron sputtering to investigate the effect of $TiO_2$ buffer layer on the electrical and optical properties of the films. For all deposition, the thickness of IGZO and $TiO_2$ Buffer layer was kept at 100 and 5 nm, respectively. In a comparison of figure of merit, IGZO films with a 5-nm-thick $TiO_2$ buffer layer show the higher figure of merit ($8.40{\times}10^{-5}{\Omega}^{-1}$) than that of the IGZO single layer films ($6.23{\times}10^{-5}{\Omega}^{-1}$) due to the enhanced optical transmittance and the decreased sheet resistance of the films. The observed results mean that a 5 nm thick $TiO_2$ buffer layer in the $IGZO/TiO_2$ films results in better electrical and optical performance than conventional IGZO single layer films.

• Journal of the Korean Society for Heat Treatment
• /
• v.29 no.6
• /
• pp.272-276
• /
• 2016

Al doped ZnO (AZO) single layer and AZO/Ag bi-layered films were deposited on the glass substrates by radio frequency and direct current magnetron sputtering and then the effect of Ag buffer layer on the electrical and optical properties of the films was investigated. The thicknesses of AZO upper layer was kept as 100 nm, while Ag buffer layer was varied from 5 to 15 nm. The observed results mean that opto-electrical properties of the AZO films is influenced with Ag buffer layer and AZO film with 10 nm thick Ag buffer layer show the higher opto-electrical performance than that of the AZO single layer film prepared in this study.

• The Transactions of the Korean Institute of Electrical Engineers C
• /
• v.55 no.1
• /
• pp.30-33
• /
• 2006

Transparent indium tin oxide (ITO) anode surface was modified using $O_3$ Plasma and organic ultrathin buffer layers were deposited on the ITO surface using 13.56 MHz RF plasma polymerization technique. The EL efficiency, operating voltage and lifetime of the organic light-emitting device (OLED) were investigated in order to study the effect of the plasma surface treatment and role of plasma polymerized organic ultrathin buffer layer. Poly methylmethacrylate (PMMA) layers were plasma polymerized on the ITO anode as buffer layer between anode and hole transport layer (HTL). The plasma polymerization of the organic ultrathin layer were carried out at a homemade capacitive-coupled RF plasma equipment. N,N'-diphenyl-N,N'(3- methylphenyl)-1,1'-diphenyl-4,4'-diamine (TPD) as HTL, Tris(8-hydroxyquinolinato) Aluminum $(Alq_3)$ as both emitting layer (EML)/electron transport layer (ETL), and aluminum layer as cathode were deposited using thermal evaporation technique. Effects of the plasma surface treatment of ITO and plasma polymerized buffer layers on the OLED performance were discussed.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2002.04b
• /
• pp.65-68
• /
• 2002

The effect of low-temperature ZnO buffer layer has been investigated for the optical properties of ZnO thin films. ZnO buffers and thin films have been deposited using the pulsed laser deposition technique. ZnO buffer layers were grown at $200^{\circ}C$ with various thickness of 0 to 60 nm, followed by raising the substrate temperature to $400^{\circ}C$ to grow $2{\mu}m$ ZnO thin films. The buffer layers could relax stresses induced by the lattice mismatch and different thermal expansion coefficients between ZnO thin films and sapphire substrate. In order to identify the optical properties of ZnO thin films, PL measurement was used. From the results of PL measurement, all the fabricated ZnO thin films with buffer layers have shown intensive UV emission with a narrow linewidth. ZnO thin films with buffer layer of 20 nm have shown the strongest UV emission. It was found that the use of ZnO buffer layer plays an important role to improve the intensive UV emission of the ZnO thin films.