• Proceedings of the Korean Vacuum Society Conference
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• 2012.02a
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• pp.319-319
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• 2012

현재 폭넓게 이용되고 있는 STI (Shallow Trench Isolation) 공정에서 active edge 부분에 발생하는 기생 transistor의 subthreshold hump 특성을 제어하는 연구가 활발히 이루어지고 있다. 일반적으로 STI 공정을 이용하는 MOSFET에서 active edge 부분의 얇게 형성된 gate oxide, sharp한 active edge 형성, STI gap-fill 공정 중에 생기는 channel dopant out-diffusion은 subthreshold hump 특성의 주된 요인이다. 이와 같은 문제점을 해결하기 위해 active edge rounding process와 channel dopant compensation의 implantation을 이용하여 subthresold hump 특성 개선을 연구하였다. 본 연구는 STI 공정에 필요한 wafer와 phosphorus를 함유한 wafer를 한 chamber 안에서 auto-doping하는 방법을 이용하여 subthresold hump 특성을 구현하였다. phosphorus를 함유한 wafer에서 빠져나온 phosphorus가 STI 공정중인 wafer로 침투하여, active edge 부분의 channel dopant인 boron 농도를 상대적으로 낮춰 active edge 부분의 가 감소하고 leakage current를 증가시킨다. transistor의 channel length, gate width이고, wafer#No가 클수록 phosphorous를 함유한 wafer까지의 거리는 가까워진다. wafer #01은 hump 특성이 없고, wafer#20은 에서 심한 subthreshold hump 특성을 보였다. channel length 고정, gate width를 ~으로 가변하여 width에 따른 영향을 실험하였다. active 부분에 대한 SCM image로 확인된 phosphorus에 의한 active edge 부분의 boron 농도 감소와 gate width vs curve에서 확인된 phosphorus에 의한 감소가 narrow width로 갈수록 커짐을 확인하였다.

• Korean Journal of Materials Research
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• v.18 no.8
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• pp.450-453
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• 2008

Mg-doped and In-Mg co-doped p-type GaN epilayers were grown in a low-pressure metal organic chemical vapor deposition technique. The effect of In doping on the p-GaN layer was studied through photoluminescence (PL), persistent photoconductivity (PPC), and transmission electron microscopy (TEM) at room temperature. For the In-doped p-GaN layer, the PL intensity increases significantly and the peak position shifts to 3.2 eV from 2.95 eV of conventional p-GaN. Additionally, In doping greatly reduces the PPC, which was very strong in conventional p-GaN. A reduction in the dislocation density is also evidenced upon In doping in p-GaN according to TEM images. The improved optical properties of the In-doped p-GaN layer are attributed to the high crystalline quality and to the active participation of incorporated Mg atoms.

• Journal of Magnetics
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• v.16 no.1
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• pp.19-22
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• 2011

[ $BiFeO_3$ ]is a multiferroic material that attracts attentions of many research groups due to its potential as being ferroelectric and ferromagnetic above room temperature. We have prepared both undoped- and Mn-doped $BiFeO_3$ by sol-gel auto-ignition method. Doping of Mn has resulted in decreasing grain size from 60 to 32 nm. X-ray diffraction data show that the samples are pure and single-phase. Infrared measurements on $BiFeO_3$ and Mn-doped $BiFeO_3$ revealed intrinsic stretching vibrations of tetrahedral sites of $Fe^{3+}$-O and of octahedral $Bi^{3+}$-O as well. On the other hand, as the Mn concentration increases, the magnetic moment of $BiFeO_3$ increases. It gives some suggestions in manipulating structural and magnetic properties of $BiFeO_3$ by doping Mn.

• Korean Journal of Materials Research
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• v.8 no.6
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• pp.526-531
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• 1998

A hydride vapor phase epitaxy (HVPE) method was performed to grow the $10~240\mu{m}$ thick GaN films on (111) spinel $MgAl_2O_4$ substrate. The GaN films on $MgAl_2O_4$ substrate revealed a photoluminescence (PL) characteristics of the impurity doped GaN by the out-diffusion and auto-doping of Mg from $MgAl_2O_4$ substrate during GaN growth. The PL spectrum measured at 10K consists of free and bound excitons related recombination transitions and impurity-related donor-acceptor pair recombination and its phonon replicas. However, the deep-level related yellow band emission was not observed. The peak energy of neutral donor bound excitonic emission and the frequency of Raman $E_2$ mode were exponentially decreased with increasing the GaN thicknesses. and the frequency of E, Raman mode was shifted with the relation of $\Delta$$\omega$=3.93$\sigma$($cm^{-1}$/GPa), where l1 (GPa) is the residual strain in the GaN epilayers.

• Nuclear Engineering and Technology
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• v.48 no.3
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• pp.608-612
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• 2016

D-(+)-glucose (Glc) was added to the original Fricke polyvinyl alcohol-glutaraldehyde-xylenol orange (FPGX) hydrogel dosimeter system to make a more stable FPGX hydrogel three-dimensional dosimeter in this paper. Polyvinyl alcohol was used as a substrate, which was combined with Fricke solution. Various concentrations of Glc were tested with linear relevant fitting for optimal hydrogel production conditions. The effects of various formulations on the stability and sensitivity of dosimeters were evaluated. The results indicated that D-(+)-Glc, as a free radical scavenger, had a great effect on stabilizing the dose response related to absorbency and reducing the auto-oxidization of ferrous ions. A careful doping with Glc could slow down the color change of the dosimeter before and after radiation without any effect on the sensitivity of the dosimeter.

• Journal of the Korean Society of Radiology
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• v.9 no.2
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• pp.67-72
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• 2015

In diagnostic radiology, the use of automatic exposure control device is internationally recommended for diagnosis and optimization. However, if exposed to prolonged radiation is a complicated manufacturing process, there is a problem that occurs decrease of various performance overall brightness sensor, which is commercially available conventional. Therefore, in this study, absorption of X-ray is high, and I want to evaluate the AEC applicability of the sensor of the photoconductor-based production has an easy advantage. Experimental results confirms the possibility of fabrication of the sensor through an increase in the SNR, with the detection efficiency superior, accurate turn-off. In addition, it is confirmed that the experimental results of the transmittance and the latent image, Ghost effect by the light conductor does not appear, in the case of a photoconductor with the exception of the PbO, 80% - and it was confirmed good transmittance of 90%. Therefore, excellent mechanical stability and poor performance due to a change of the doping concentration than the existing products that have been put to practical use, the sensor easy photoconductor based, fabrication and can be applied as AEC sensor is expected.

• Korean Journal of Materials Research
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• v.8 no.8
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• pp.667-671
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• 1998

The photoluminescence (pL) characteristics of hydride vapor phase epiyaxy (HVPE) grown GaN films on $MgAl_{2}O_{4}$ substrate were investigated with several growth conditions. The GaN films on $MgAl_{2}O_{4}$ substrate is autodoped with Mg atoms which thermally out-diffused from substrate lead to a PL characteristics of impurity doped ones. The Mg-related emission band intensity decreased with growth temperature may due to the evaporation of Mg atoms at the GaN film surfaces. and it also decreased with GaN film thicknesses. We can estimate the diffusion coefficient of Mg atoms in GaN under the consideration of diffusion phenomena between two infinite solids lead to a value of D= 2$\times$$lO^{-10}\textrm{cm}^2/sec.