• 한국정보디스플레이학회:학술대회논문집
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• 2006.08a
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• pp.426-429
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• 2006

We investigated the electrooptical properties of a carbon nanotube (CNT)-doped nematic liquid crystal (LC) cell. Experimental results reveal that the doped CNTs influence the elastic constant of LC-CNT dispersion. Using a small amount of CNT dopant, the rise time of the LC cell is nearly invariant; the threshold voltage of the cell increases due to the increase in the elastic constant of LC-CNT dispersion. At a higher CNT concentration, the marked increase in the dielectric anisotropy of LC-CNT dispersion markedly decreases the rise time and threshold voltage of the LC cell. The fall time of this cell decreases with increasing CNT concentration due to the increase in elastic constant and the slight increase in viscosity of LC-CNT dispersion. The rise time and the fall time of the LC cell are decreased simultaneously when the LC host is doped with a moderate amount of CNT dopant.

• ETRI Journal
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• v.25 no.4
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• pp.247-252
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• 2003

This paper presents results from experiments on laser-annealed SiGe-selective epitaxial growth (LA-SiGe-SEG). The SiGe-SEG technology is attractive for devices that require a low band gap and high mobility. However, it is difficult to make such devices because the SiGe and the highly doped region in the SiGe layer limit the thermal budget. This results in leakage and transient enhanced diffusion. To solve these problems, we grew in situ doped SiGe SEG film and annealed it on an XMR5121 high power XeCl excimer laser system. We successfully demonstrated this LA-SiGe-SEG technique with highly doped Ge and an ultra shallow junction on p-type Si (100). Analyzing the doping profiles of phosphorus, Ge compositions, surface morphology, and electric characteristics, we confirmed that the LA-SiGe-SEG technology is suitable for fabricating high-speed, low-power devices.

• Macromolecular Research
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• v.10 no.5
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• pp.286-290
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• 2002

The FT-Raman spectra of trans-polyacetylene films doped lightly with iodine were obtained with the 1320-nm laser line. The observed Raman bands are attributed to positively charged domains created by acceptor doping. The observed Raman wavenumbers of the V$_2$, (CC stretch), V$_3$, and V$_4$ bands (mixed of CC stretch and CH in-plan bending) of iodine-doped form are slightly higher than those of the corresponding bands of pristine trans-polyacetylene, whereas the contrary is the case for V$_1$, and (C=C stretch) of iodine-doped form. In particular, these upshifts of the V$_2$ and V$_3$ bands are distinguished from the downshifts of these bands in donor doping. The origin of doping induced Raman bands is discussed in terms of solitons and polarons.

• Journal of Magnetics
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• v.16 no.4
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• pp.332-336
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• 2011

We studied the effect on the electronic and magnetic properties of the N defect in clean and Cu-doped wurtzite III-nitrides by using the first-principles calculations. When it is doped two Cu atoms in the nearest neighboring sites, the system of AlN, GaN, or InN with the N vacancy is energetically more favorable than that without the N vacancy site. When the Cu concentration increases, the total magnetic moment of a supercell becomes small. The ferromagnetism of Cu atom is very low due to the weak 3d-3d coupling. It is noticeable that the spin-exchange interaction between the Cu-3d and N defect states is important.

• Journal of the Semiconductor & Display Technology
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• v.10 no.4
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• pp.43-46
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• 2011

In this study, we investigated the effects of the post Ar plasma treatment at different RF powers for various durations on electrical, structural, and optical properties of relatively thin Al-doped zinc oxide films. The sheet resistance was observed to decrease rapidly for the first 5min, beyond which the resistance apparently saturated. As the RF power increased, the grain size and the interplanar distance of (002) planes also increased. The observed decrease in sheet resistance was stated to be a consequence of Al and/or Zn interstitials as well as grain growth. It was also found that Ar plasma treatment increased the transmittance of Al-doped zinc oxide films in most of the visible light range below the blue light.

• Korean Journal of Optics and Photonics
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• v.12 no.6
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• pp.507-510
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• 2001

A numerical analysis based on the nonlinear Schroedinger equation is presented to analyze the propagation stability of the average soliton in a simple nonlinear amplifying loop mirror. The ratio of amplification period to soliton period and the length fraction of the erbium-doped fiber in the loop are varied to investigate their effects on the soliton stability. It is observed that stable soliton propagation is obtained even when the amplification period is only slightly shorter than the soliton period when the length fraction of the erbium-doped fiber in the loop is small, which is different from the previously published condition for stable average soliton propagation.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.38 no.6
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• pp.401-415
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• 1989

A simple but accurate analytical model for the lateral channel electric field in gate-offset structured Lightly Doped Drain MOSFET has been developed. Our model assumes Gaussian doping profile, rather than simple uniform doping, for the lightly doped region and our model can be applied to LDD structures where the junction depth of LDD is not identical to the heavily doped drain. The validity of our model has been proved by comparing our analytical results with two dimensional device simulations. Due to its simplicity, our model gives a better understanding of the mechanisms involved in reducing the electric field in the LDD MOSFET. The model shows clearly the dependencies of the lateral channel electric field on the drain and gate bias conditions and process, design parameters. Advantages of our analytical model over costly 2-D device simulations is to identify the effects of various parameters, such as oxide thickness, junction depth, gate/drain bias, the length and doping concentration of the lightly doped region, on the peak electric field that causes hot-electron pohenomena, individually. Our model can also find the optimum doping concentration of LDD which minimizes the peak electric field and hot-electron effects.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.32 no.5
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• pp.376-381
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• 2019

In this work, we evaluated the structural, electrical and optical properties of $Ge_8Sb_2Te_{11}$ and Cu-doped $Ge_8Sb_2Te_{11}$ thin films prepared by rf-magnetron reactive sputtering. The 200-nm-thick deposited films were annealed in a range of $100{\sim}400^{\circ}C$ using a furnace in an $N_2$ atmosphere. The amorphous-to-crystalline phase changes of the thin films were investigated by X-ray diffraction (XRD), UV-Vis-IR spectrophotometry, a 4-point probe, and a source meter. A one-step phase transformation from amorphous to face-centered-cubic (fcc) and an increase of the crystallization temperature ($T_c$) was observed in the Cu-doped film, which indicates an enhanced thermal stability in the amorphous state. The difference in the optical energy band gap ($E_{op}$) between the amorphous and crystalline phases was relatively large, approximately 0.38~0.41 eV, which is beneficial for reducing the noise in the memory devices. The sheet resistance($R_s$) of the amorphous phase in the Cu-doped film was about 1.5 orders larger than that in undoped film. A large $R_s$ in the amorphous phase will reduce the programming current in the memory device. An increase of threshold voltage ($V_{th}$) was seen in the Cu-doped film, which implied a high thermal efficiency. This suggests that the Cu-doped $Ge_8Sb_2Te_{11}$ thin film is a good candidate for PRAM.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.06a
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• pp.140-140
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• 2009

The Metal-ferroelectric-semiconductor (MFS) structure has superior advantages such as high density integration and non-destructive read-out operation. However, to obtain the desired electrical characteristics of an MFS structure is difficult because of interfacial reactions between ferroelectric thin film and Si substrate. As an alternative solution, the MFS structure with buffer insulating layer, i.e. metal-ferroelectric-insulator-semiconductor (MFIS), has been proposed to improve the interfacial properties. Insulators investigated as a buffer insulator in a MFIS structure, include $Ta_2O_5$, $HfO_2$, and $ZrO_2$ which are mainly high-k dielectrics. In this study, we prepared the Dy-doped $La_2O_3$ solution buffer layer as an insulator. To form a Dy-doped $La_2O_3$ buffer layer, the solution was spin-coated on p-type Si(100) wafer. The coated Dy-doped $La_2O_3$ films were annealed at various temperatures by rapid thermal annealing (RTA). To evaluate electrical properties, Au electrodes were thermally evaporated onto the surface of the samples. Finally, we observed the surface morphology and crystallization quality of the Dy-doped $La_2O_3$ on Si using atomic force microscopy (AFM) and x-ray diffractometer (XRD), respectively. To evaluate electrical properties, the capacitance-voltage (C-V) and current density-voltage (J-V) characteristics of Au/Dy-doped La2O3/Si structure were measured.

• Korean Journal of Materials Research
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• v.29 no.9
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• pp.542-546
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• 2019

We investigate the characteristics of self-assembled quantum dot infrared photodetectors(QDIPs) based on doping level. Two kinds of QDIP samples are prepared using molecular beam epitaxy : $n^+-i(QD)-n^+$ QDIP with undoped quantum dot(QD) active region and $n^+-n^-(QD)-n^+$ QDIP containing Si direct doped QDs. InAs QDIPs were grown on semi-insulating GaAs (100) wafers by molecular-beam epitaxy. Both top and bottom contact GaAs layer are Si doped at $2{\times}10^{18}/cm^3$. The QD layers are grown by two-monolayer of InAs deposition and capped by InGaAs layer. For the $n^+-n^-(QD)-n^+$ structure, Si dopant is directly doped in InAs QD at $2{\times}10^{17}/cm^3$. Undoped and doped QDIPs show a photoresponse peak at about $8.3{\mu}m$, ranging from $6{\sim}10{\mu}m$ at 10 K. The intensity of the doped QDIP photoresponse is higher than that of the undoped QDIP on same temperature. Undoped QDIP yields a photoresponse of up to 50 K, whereas doped QDIP has a response of up to 30 K only. This result suggests that the doping level of QDs should be appropriately determined by compromising between photoresponsivity and operating temperature.