• Journal of the Korean institute of surface engineering
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• v.48 no.4
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• pp.163-168
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• 2015

Graphene has attracted much attention due to its remarkable physical properties and potential applications in many fields. In special, the electronic properties of graphene are influenced by the number of layer, stacking sequence, edge state, and doping of foreign elements. Recently, many efforts have been dedicated to alter the electronic properties by doping of various species, such as hydrogen, oxygen, nitrogen, ammonia and etc. Here, we report our recent results of plasma doping on graphene. We prepared mechanically exfoliated graphene, and performed the plasma treatment using ammonia gas for nitrogen doping. The direct-current plasma system was used for plasma ignition. The doping level was estimated from the number of peak shift of G-band in Raman spectra. The upshift of G-band was observed after ammonia plasma treatment, which implies electron doping to graphene.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.31A no.5
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• pp.126-133
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• 1994

Doping effects and semiconductor behaviors of the dispersed p- and n-Si, p- and n- GaAs particles in the aqueous electrolyte have been studied using microelectrophoretic, voltammetric and chronoamperometric techniques. The cations (K$^{+}$) are adsorbed on both the p- and n- Si particle surfaces regardless of the sign of space charges in the depletion layers, i.e. doping profiles. The surface states are negatively charged acceptor states. On the other hand, the anions (CI$^{-}$) are adsorbed on both the p- and n- GaAs particle surfaces regardless of the sign of space charges in the depletion layers, i.e. doping profiles. The surface states are positively charged donor states. Under the same conditions, electrophoretic mobilities, electrochemical processes, doping effects and related semiconductor behaviors of the Si and the GaAs particles are similar regardless of the doping profiles, i. e. dopants and doping concentrations. The doping effects and related semiconductor behaviors of the dispersed p- and n- type semiconductor particles are gradually lost with decreasing dimensions.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2010.06a
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• pp.133-133
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• 2010

We studied the thermal and electric effect of 2D and 3D p-n photovoltaic diode structures with and without surface texturing. By analyzing the numerical simulation results of I-V characteristics and lattice temperature distributions, we systematically studied the effect of different texturing structures and different doping concentration on the characteristics of the silicon p-n photovoltaic devices. The, efficiency of the device with the surface texturing shows more than ~ 2% enhancement compared to the reference devices without texturing. The tendency of the efficiency of doping concentration has been studied with boron doping of $10^{14}{\sim}10^{17}cm^{-3}$ and phosphorus doping of $10^{15}cm^{-3}$. In addition to that, the study of changing phosphorus doping of $10^{15}{\sim}10^{18}cm^{-3}$ with boron doping of $10^{14}cm^{-3}$ has been examined. It has been shown that the texturing structure not only improves the light trapping but also plays an important role in the heat radiation.

• 한국태양에너지학회:학술대회논문집
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• 2011.11a
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• pp.149-153
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• 2011

The PC1D is widely used for modeling the properties of crystalline silicon solar cell. Optimized doping profile in crystalline silicon solar cell fabrication is necessary to obtain high conversion efficiency. Doping profile in the forms of a uniform, gaussian, exponential and erfc function can be simulated using the PC1D program. In this paper, the doping profiles including junction depth, dopant concentration on surface and the form of doping profile (gaussian, gaussian+erfc function) were changed to study its effect on electrical properties of solar cell. As decreasing junction depth and doping concentration on surface, electrical properties of solar cell were improved. The characteristics for the solar cells with doping profile using the combination of gaussian and erfc function showed better open-circuit voltage, short-circuit current and conversion efficiency.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.19 no.1
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• pp.23-28
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• 2006

In this paper, breakdown voltage and on-resistance characteristics of the surface doped SOI RESURF LDMOSFET were investigated as a function of surface doping depth. In order to verify the variation of characteristics, two-dimensional device simulation was carried out. Breakdown voltage of the proposed structure is varied from $73 {\~}138V$ while surface doping depth varied from $0.5{\~}2.0{\mu}m$. And on-resistance is decreased from $0.18{\~}0.143{\Omega}/cm^2$ while surface doping depth increased from $0.5 {\~}2.0{\mu}m$. Maximum breakdown voltage of the proposed structure is 138 V at $1.5{\mu}m$ depth of surface doping, yielding $22.1\%$ of improvement of breakdown voltage in comparison with that of the conventional SOI RESURF LDMOSFET with same epi-layer concentration. On-resistance characteristic is also improved about $21.7\%$.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.13 no.7
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• pp.551-556
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• 2000

We have investigated the effect of surface In composition with Si cell temperature on the In$_{0.1}$/Ga$_{0.9}$/As epilayers grown on GaAs substrates. The epilayers were grown by molecular beam epitaxy(MBE) method and were characterized by the pthotoreflectance(PR) measurements. The E$_{o}$ bandgap energies of In$_{0.1}$/Ga$_{0.9}$/As epilayers were observed at around 1.28 eV at room temperature, and the additional shoulder peaks appeared at the higher energies than E$_{o}$ with increase of Si doping concentrations. The intensity of the additional shoulder peak was decreased with lowering the measurement temperature and the peak disappeared with the increase of surface etching time. This results hows that In composition at surface of InGaAs epilayer is decreased with the increase of the doping cell temperature. We consider that the reason of the decrease of In composition at the surface should be due to In re-evaporation from the surface by radiation heat of Si doping cell.ell.ell.ell.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.02a
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• pp.603-603
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• 2012

최근에 전면 emitter의 doping profile이 다른 selective emitter solar cell은 실제 제작시단파장 영역에서 많은 gain을 얻을 수 없어 LBC 구조의 태양전지에 관한 연구가 많이 진행되고 있다. 본 연구는 TCAD simulation을 이용하여 후면에 형성되는 locally doped BSF(p++) region의 doping profile의 변화에 따른 태양전지 특성에 관한 연구이다. Al으로 형성되는 local back contact의 doping depth 및 surface concentration에 따른 전기적, 광학적 분석을 통해 주도적인 인자를 분석하고 최적화하였다. 특히 doping depth에 따른 변화보다는 surface concentration의 변화에 따른 특성변화가 주도적으로 나타났다.

• Journal of the Korean institute of surface engineering
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• v.29 no.5
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• pp.449-453
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• 1996

In order to improve EL performance, anthracene was doped into the 8-hydroxyquinoline-aluminum (Alq$^3$) light-emitting layer of organic double layered EL cells. The EL cells were fabricated on ITO glass substrates by vacuum deposition. Doping of anthracene to the light-emitting $Alq^3$layer was performed by means of co-evaporation. The doping concentration was changed in the range of 5 to 30 wt.%. It was confirmed that anthracene doping of appropriate concentration increased the available current density and brightness of the EL cells. Carrier mobility of the $Alq^3$ layer was measured by time of flight method. The influence of anthracene doping on the cell performance was discussed.

• Journal of the Korean institute of surface engineering
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• v.27 no.4
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• pp.234-240
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• 1994

A large area impurity doping method for poly-Si TFT LCD has been developed. The advantage of this method is the doping of impurities into Si over a large area without mass separation and beam scanning. Phosphorus diluted in hydrogen was discharged by RF(13.56MHz) power and ions from discharged gas were accelerated by DC acceleration voltage and were implanted into deposited Si films. The annealing characteristic of this method was similar to that of the ion implantation method in the low doping concentration. Three mechanisms were evolved in the annealing characteristics of phosphorus doped Si films. Point defects annihilation and the retrogradation of dopant atoms at grain boundaries as a result of grain growth played a major role at low and high annealing temperature, respectively. However, due to the dopant segregation, the reverse annealing range existed at intermediate annealing temperature.

• Journal of the Korean institute of surface engineering
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• v.54 no.6
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• pp.348-356
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• 2021

In this study, optical diagnosis of plasma was performed for nitrogen doping in graphene using a horizontal inductively coupled plasma (ICP) system. Graphene was prepared by mechanical exfoliation and the ICP system using nitrogen gas was ignited for plasma-induced and defect-suppressed nitrogen doping. In order to derive the optimum condition for the doping, plasma power, working pressure, and treatment time were changed. Optical emission spectroscopy (OES) was used as plasma diagnosis method. The Boltzmann plot method was adopted to estimate the electron excitation temperature using obtained OES spectra. Ar ion peaks were interpreted as a reference peak. As a result, the change in the concentration of nitrogen active species and electron excitation temperature depending on process parameters were confirmed. Doping characteristics of graphene were quantitatively evaluated by comparison of intensity ratio of graphite (G)-band to 2-D band, peak position, and shape of G-band in Raman profiles. X-ray photoelectron spectroscopy also revealed the nitrogen doping in graphene.