• JSTS:Journal of Semiconductor Technology and Science
• /
• v.8 no.1
• /
• pp.80-84
• /
• 2008

We systematically investigated the resistive switching properties of thin $TiO_2$ films on Pt/Ti/$SiO_2$/Si substrates that were embedded with a Co ultra thin layer. An in-situ sputtering technique was used to grow both films without breaking the chamber vacuum. A stable bipolar switching in the current-voltage curve was clearly observed in $TiO_2$ films with an embedded Co ultra thin layer, addressing the high and low resistive state under a bias voltage sweep. We propose that the underlying origin involved in the bipolar switching may be attributed to the interface redox reaction between the Co and $TiO_2$ layers. The improved reproducible switching properties of our novel structures under forward and reverse bias stresses demonstrated the possibility of future non-volatile memory elements in a simple capacitive-like structure.

• Proceedings of the IEEK Conference
• /
• 2003.07b
• /
• pp.1065-1068
• /
• 2003

For the first time, high quality ultra-thin strained Si/SiGe on Insulator (SGOI) substrate with total SGOI thickness( $T_{Si}$ + $T_{SiGe}$) of 13 nm is developed to combine the device benefits of strained silicon and SOI. In the case of 6- 10 nm-thick top silicon, 100-110 % $I_{d,sat}$ and electron mobility increase are shown in long channel nFET devices. However, 20-30% reduction of $I_{d,sat}$ and electron mobility are observed with 3 nm top silicon for the same long channel device. These results clearly show that the FETs operates with higher performance due to the strain enhancement from the insertion of SiGe layer between the top silicon layer and the buried oxide(BOX) layer. The performance degradation of the extremely thin( 3 nm ) top Si device can be attributed to the scattering of the majority carriers at the interfaces.

• The Transactions of the Korean Institute of Electrical Engineers C
• /
• v.49 no.1
• /
• pp.13-18
• /
• 2000

We have fabricated LB ultra-thin films of maleate system by LB technique and evaluated the deposited status of LB ultra-thin films by I-V characteristics such as capacitance. It was found that the thickness of LB ultra-thin per layer is $27~30[{\AA}]$ by XRD. And, we have known that the conductivity along the horizontal direction of LB ultra-thin films was about $10^{-8}[S/cm]$, it corresponds to the semiconducting materials. Also, the I-V characteristics along the vertical direction of LB ultra-thin films was dominated by Schottky type current, the activation energy obtained by current-temperature characteristics was about 0.84[eV] and the conductivity was about $10^{-14}[S/cm]$, it corresponds to the insulator. And, the anisotropic conduction mechanism of the LB ultra-thin films in vertical direction and horizontal direction is determined by the hydrophilic group and the hydrophobic group in LB ultra-thin films. The above results are applicable to the semiconductor devices such as switching device, which function at the molecular level.

• Proceedings of the Materials Research Society of Korea Conference
• /
• 2011.10a
• /
• pp.19.2-19.2
• /
• 2011

The $(Sr_{0.75},\;La_{0.25})TiO_3$ (SLTO) ultra-thin films with various thicknesses have been grown on Ti-O terminated $SrTiO_3$(100) substrate using Laser-Molecular Beam Epitaxy (Laser MBE). By monitoring the in-situ specular spot intensity oscillation of reflection high energy electron diffraction (RHEED), we controlled the layer-by-layer film growth. The film structure and topography were verified by atomic force microscopy (AFM) and high resolution thin film x-ray diffraction by the synchrotron x-ray radiation. We have also investigated the electronic band structure using x-ray absorption spectroscopy (XAS). The ultra thin SLTO film exhibits thickness driven metal-insulator transition around 8 unit cell thickness when the film thickness progressively reduced to 2 unit cell. The SLTO thin films with an insulating character showed band splitting in Ti $L_3-L_2$ edge XAS spectrum which is attributed to Ti 3d band splitting. This narrow d band splitting could drive the metal-insulator transition along with Anderson Localization. In optical conductivity, we have found the spectral weight transfer from coherent part to incoherent part when the film thickness was reduced. This result indicates the possibility of enhanced electron correlation in ultra thin films.

• Transactions of Materials Processing
• /
• v.29 no.6
• /
• pp.323-330
• /
• 2020

The surface region of a sheet metal may have different characteristics from the inner region because the surface region is less restricted than the interior. In addition, the grains on the free surface are less hardened because of surface adsorption of the dislocations, rather than piling up. In the case of bulk or thick sheet metals, this effect is negligible because the fraction of the surface region is much smaller than that of the inner region. However, this surface effect is important in the case of ultra-thin sheet metals. In order to evaluate the surface effect, tensile and bending tests were performed for the SS304 stainless steel with a thickness of 0.39 mm. The bending force predicted using the tensile behavior is higher than the measurement because of the surface effect. To account for the surface effect, the surface layer model was developed by dividing the sheet section into surface and inner layers. The mechanical behaviors of the two regions were calibrated using the tensile and bending properties. The surface layer model reproduced the bending behavior of the ultra-thin sheet metal.

• Applied Science and Convergence Technology
• /
• v.25 no.2
• /
• pp.32-35
• /
• 2016

Using conventional deposition techniques, we demonstrate a method to fabricate ultra-smooth 10 nm silver films without using a wetting layer or co-depositing another material. The argon working pressure plays a crucial role in achieving an excellent surface flatness for silver films deposited by DC magnetron sputtering on an InP substrate. The formation of ultra-smooth silver thin films is very sensitive to the argon pressure. At the optimum deposition condition, a uniform silver film with an rms surface roughness of 0.81 nm has been achieved.

• Journal of the Korean Institute of Navigation
• /
• v.19 no.4
• /
• pp.83-92
• /
• 1995

In this study, a vertical type LPE system has been developed for III-V semiconductor compounds single crystal growth. On the basis of the experience & basic study using this system, the system modification has been carried out for a ultra thin multi-layer single crystal. The temperature fluctuation was within ${\pm}0.006^{\circ}C$ at $800^{\circ}C$, temperature uniformity for graphite boat around was within ${\pm}0.15^{\circ}C$ at $650^{\circ}C$, and cooling rate was controllable from $2.2^{\circ}C$/min to $0.05^{\circ}C$/min. As a result it is considered to satisfy the condition to grow a ultra thin layer single crystal of III-V semiconductor compounds.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2007.06a
• /
• pp.503-504
• /
• 2007

$Bi_2Sr_2Ca_{n-1}Cu_nO_x$(n=0, 1, 2)superconducting thin films have been fabricated by atomic layer-by-layer deposition at an ultra low growth rate using IBS(Ion Beam Sputtering) method. During the deposition, 90 mol% ozone gas of typical pressure of $1{\sim}9{\times}10^{-5}$ Torr are supplied with ultraviolet light irradiation for oxidation. XRD and RHEED investigations reveal out that a buffer layer with some different compositions is formed at the early deposition stage of less than 10 units cell and then Bi-2201 oriented along the c-axis is grown.

• Journal of the Microelectronics and Packaging Society
• /
• v.29 no.3
• /
• pp.49-53
• /
• 2022

Ultra-thin glass (UTG) has been widely used in foldable display as a cover window for the protection of display and has a great potential for rollable display and various flexible electronics. The foldable display is under impact loading by bending and touch pen and exposed to other external impact loads such as drop while people are using it. These external impact loads can cause cracks or fracture to UTG because it is very thin under 100 ㎛ as well as brittle. Cracking and fracture lead to severe reliability problems for foldable smartphone. Thus, this study constructs finite element analysis (FEA) model for the pen drop test which can measure the impact resistance of UTG and conducts mechanical modeling to improve the reliability of UTG under impact loading. When a protective layer is placed to an upper layer or lower layer of UTG layer, stress mechanism which is applied to the UTG layer by pen drop is analyzed and an optimized structure is suggested for reliability improvement of UTG layer. Furthermore, maximum principal stress values applied at the UTG layer are analyzed according to pen drop height to obtain maximum pen drop height based on the strength of UTG.

• Proceedings of the IEEK Conference
• /
• 1998.06a
• /
• pp.343-346
• /
• 1998

Ultra-thin gate oxide in MOS devices are subjected to high-field stress during device operation, which degrades the oxide and exentually causes dielectric breakdown. In this paper, we investigate the electrical properties of ultra-thin nitrided oxide (NO) and reoxidized nitrided oxide(ONO) films that are considered to be promising candidates for replacing conventional silicon dioxide film in ULSI level integration. We study vriations of I-V characteristics due to F-N tunneling, and time-dependent dielectric breakdown (TDDB) of thin layer NO and ONO depending on nitridation and reoxidation condition, and compare with thermal $SiO_{2}$. From the measurement results, we find that these NO and ONO thin films are strongly depending on its condition and that optimized reoxided nitrided oxides (ONO) films show superior dielectric characteristics, and breakdown-to-change ( $Q_{bd}$ ) performance over the NO films, while maintaining a similar electric field dependence compared to NO layer.