• The Transactions of the Korean Institute of Electrical Engineers C
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• v.55 no.6
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• pp.297-301
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• 2006

In the present work, we investigate the characteristics of new composition material, chalcogenide $Ge_1Se_1Te_2$ material in order to overcome the problems of conventional PRAM devices. The Tc of $Ge_1Se_1Te_2$ bulk was measured $231.503^{\circ}C$ with DSC analysis. For static DC test mode, at low voltage, two different resistances are observed. depending on the crystalline state of the phase-change resistor. In the first sweep, the as-deposited amorphous $Ge_1Se_1Te_2$ showed very high resistance. However when it reached the threshold voltage(about 11.8 V), the electrical resistance of device was drastically reduced through the formation of an electrically conducting path. The phase transition between the low conductive amorphous state and the high conductive crystal]me state was caused by the set and reset pulses respectively which fed through electrical signal. Set pulse has 4.3 V. 200 ns. then sample resistance is $80\sim100{\Omega}$. Reset pulse has 8.6 V 80 ns, then the sample resistance is $50{\sim}100K{\Omega}$. For such high resistance ratio of $R_{reset}/R_{set}$, we can expect high sensing margin reading the recorded data. We have confirmed that phase change properties of $Ge_1Se_1Te_2$ materials are closely related with the structure through the experiment of self-heating layers.

• Proceedings of the KIEE Conference
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• 2007.10c
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• pp.172-174
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• 2007

An electronic watt-hour meter with high-precision measurement technology can provide many valuable metering data of a real-time system measurements, such as per-phase voltage, ampere, active power, reactive power, apparent power, power factor, and system frequency. Also many of accumulated metering data such as active energy, reactive energy, apparent energy, and load profile can be gettable from an electronic watt-hour meter[1]. This paper presents an approach of the small-sized AMR (Automatic Meter Reading) that provides customers with a very valuable electrical service. This AMR service transmits lots of a valuable metering data by using ZigBee communication module, so that users resided in their premises can use the information to audit a power quality and improve their electrical conditions by using the PQ monitoring device equipped with ZigBee receiver. This PQ monitoring device shows metering data on LCD and transmits to the PC through an internal network. Also, the device can keep the valuable meter data into a built-in non-volatile memory. The final goal of this paper is to better understand the power quality of electrical systems and offer the power qualify information for the convenience of all power consumers.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.6
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• pp.2697-2701
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• 2012

The yield of OTP devices using anti-fuse MOS capacitor have been affected by the input resistance, the size of the pass transistor and the read transistor, and the readout voltage of programed cell. To investigate the element which gives an effect to yield, we analyze the full map data of the resistance characterization of OTP device and those data in a various experimental condition. As a result, we got the optimum conditions which is necessary to the yield improvement. The optimum conditions are as follows: Input resistance is 50 ohms, the channel length of pass transistor is 10um, read voltage is 2.8 volt, respectively.

• Proceedings of the Materials Research Society of Korea Conference
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• 2011.10a
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• pp.20.1-20.1
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• 2011

The nano-sized quantum structure has been an attractive candidate for investigations of the fundamental physical properties and potential applications of next-generation electronic devices. Metal nano-particles form deep quantum wells between control and tunnel oxides due to a difference in work functions. The charge storage capacity of nanoparticles has led to their use in the development of nano-floating gate memory (NFGM) devices. When compared with conventional floating gate memory devices, NFGM devices offer a number of advantages that have attracted a great deal of attention: a greater inherent scalability, better endurance, a faster write/erase speed, and more processes that are compatible with conventional silicon processes. To improve the performance of NFGM, metal nanocrystals such as Au, Ag, Ni Pt, and W have been proposed due to superior density, a strong coupling with the conduction channel, a wide range of work function selectivity, and a small energy perturbation. In the present study, bismuth metal nanocrystals were self-assembled within high-k $Bi_2Mg_{2/3}Nb_{4/3}O_7$ (BMN) films grown at room temperature in Ar ambient via radio-frequency magnetron sputtering. The work function of the bismuth metal nanocrystals (4.34 eV) was important for nanocrystal-based nonvolatile memory (NVM) applications. If transparent NFGM devices can be integrated with transparent solar cells, non-volatile memory fields will open a new platform for flexible electron devices.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.33 no.6
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• pp.445-449
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• 2020

Non-volatile memory is approaching its fundamental limits with the Si₃N₄ storage layer, necessitating the use of alternative materials to achieve a higher programming/erasing speed, larger storage window, and better data retention at lower operating voltage. This limitation has restricted the development of the charge-trap memory, but can be addressed by using high-k dielectrics. The paper reviews the doping of nitrogen, titanium, and yttrium on high-k dielectrics as a storage layer by comparing MONOS devices with different storage layers. The results show that nitrogen doping increases the storage window of the Gd₂O₃ storage layer and improves its charge retention. Titanium doping can increase the charge capture rate of HfO₂ storage layer. Yttrium doping increases the storage window of the BaTiO₃ storage layer and improves its fatigue characteristics. Parameters such as the dielectric constant, leakage current, and speed of the memory device can be controlled by maintaining a suitable amount of external impurities in the device.

• Proceedings of the Korean Fiber Society Conference
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• 2007.11a
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• pp.123-126
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• 2007

• JSTS:Journal of Semiconductor Technology and Science
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• v.17 no.1
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• pp.1-6
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• 2017

This paper presents an optimized adoption of NVM for the storage system of heterogeneous applications. Our analysis shows that a bulk of I/O does not happen on a single storage partition, but it is varied significantly for different application categories. In particular, journaling I/O accounts for a dominant portion of total I/O in DB applications like OLTP, whereas swap I/O accounts for a large portion of I/O in graph visualization applications, and file I/O accounts for a large portion in web browsers and multimedia players. Based on these observations, we argue that maximizing the performance gain with NVM is not obtained by fixing it as a specific storage partition but varied widely for different applications. Specifically, for graph visualization, DB, and multimedia player applications, using NVM as a swap, a journal, and a file system partitions, respectively, performs well. Our optimized adoption of NVM improves the storage performance by 10-61%.

• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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• pp.174-174
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• 2014

Memristor devices are one of the most promising candidate approaches to next-generation memory technologies. Memristive switching phenomena usually rely on repeated electrical resistive switching between non-volatile resistance states in an active material under the application of an electrical stimulus, such as a voltage or current. Recent reports have explored the use of variety of external operating parameters, such as the modulation of an applied magnetic field, temperature, or illumination conditions to activate changes in the memristive switching behaviors. Among these possible choices of signal controlling factors of memristor, photon is particularly attractive because photonic signals are not only easier to reach directly over long distances than electrical signal, but they also efficiently manage the interactions between logic devices without any signal interference. Furthermore, due to the inherent wave characteristics of photons, the facile manipulation of the light ray enables incident light angle controlled memristive switching. So that, in the tautological sense, device orienting position with regard to a photon source determines the occurrence of memristive switching as well. To demonstrate this position controlled memory device functionality, we have fabricated a metal-semiconductor-metal memristive switching nanodevice using ZnO nanorods. Superhydrophobicity employed in this memristor gives rise to illumination direction selectivity as an extra controlling parameter which is important feature in emerging. When light irradiates from a point source in water to the surface treated device, refraction of light ray takes place at the water/air interface because of the optical density differences in two media (water/air). When incident light travels through a higher refractive index medium (water; n=1.33) to lower one (air; n=1), a total reflection occurs for incidence angles over the critical value. Thus, when we watch the submerged NW arrays at the view angles over the critical angle, a mirror-like surface is observed due to the presence of air pocket layer. From this processes, the reversible switching characteristics were verified by modulating the light incident angle between the resistor and memristor.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.17 no.12
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• pp.1283-1288
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• 2004

Metal-ferroelectric-insulator-semiconductor(WFIS) capacitors using rapid thermal annealed LiNbO$_3$/AlN/Si(100) structure were fabricated and demonstrated nonvolatile memory operations. The capacitors on highly doped Si wafer showed hysteresis behavior like a butterfly shape due to the ferroelectric nature of the LiNbO$_3$ films. The typical dielectric constant value of LiNbO$_3$ film in the MFIS device was about 27, The gate leakage current density of the MFIS capacitor was 10$^{-9}$ A/cm$^2$ order at the electric field of 500 kV/cm. The typical measured remnant polarization(2P$_{r}$) and coercive filed(Ec) values were about 1.2 $\mu$C/cm$^2$ and 120 kV/cm, respectively The ferroelectric capacitors showed no polarization degradation up to 10$^{11}$ switching cycles when subjected to symmetric bipolar voltage pulses of 1 MHz. The switching charges degraded only by 10 % of their initial values after 4 days at room temperature.e.

• Proceedings of the KIEE Conference
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• 2003.07c
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• pp.1562-1564
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• 2003

In this study, PZT thin films were fabricated using sol-gel processing onto Si/$SiO_2$/Ti/Pt substrates. PZT sol with different Zr/Ti ratio(20/80, 30/70, 40/60, 52/48) were prepared, respectively. The films were fabricated by using the spin-coating method on substrates. The films were heat treated at $450^{\circ}C,\;650^{\circ}C$ by rapid thermal annealing(RTA). The preferred orientation of the PZT thin films were observed by X-ray diffraction(XRD), and Scanning electron microscopy(SEM). All of the resulting PZT thin films were crystallized with perovskite phase. The fine crystallinity of the films were fabricated. Also, we found that the ferroelectric properties from the dielectric constant of the PZT thin films were over 600 degrees, P-E hysteresis constant. And the leakage current densities of films were lower than $10^{-8}A/cm^2$. It is concluded that the PZT thin films by sol-gel process to be convinced of application for ferroelectric memory device.