• Korean Journal of Metals and Materials
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• v.49 no.11
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• pp.905-909
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• 2011

The formation of front metal contact silicon solar cells is required for low cost, low contact resistance to silicon surfaces. One of the available front metal contacts is Ni/Cu plating, which can be mass produced via asimple and inexpensive process. A selective emitter, meanwhile, involves two different doping levels, with higher doping (${\leq}30{\Omega}/sq$) underneath the grid to achieve good ohmic contact and low doping between the grid in order to minimize the heavy doping effect in the emitter. This study describes the formation of a selective emitter and a nickel silicide seed layer for the front metallization of silicon cells. The contacts were thickened by a plated Ni/Cu two-step metallization process on front contacts. The experimental results showed that the Ni layer via SEM (Scanning Electron Microscopy) and EDX (Energy dispersive X-ray spectroscopy) analyses. Finally, a plated Ni/Cu contact solar cell displayed efficiency of 18.10% on a $2{\times}2cm^2$, Cz wafer.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.08a
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• pp.307-307
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• 2012

In this study, we investigated that the resistance switching characteristics of Al-doped MgOx films with increasing Al doping concentration and increasing film thickness. The Al-doped MgOx based ReRAM devices with a TiN/Al-doped MgOx/Pt/Ti/SiO2 were fabricated on Si substrates. The 5 nm, 10 nm, and 15 nm thick Al-doped MgOx films were deposited by reactive dc magnetron co-sputtering at $300^{\circ}C$ and oxygen partial ratio of 60% (Ar: 16 sccm, O2: 24 sccm). Micro-structure of Al-doped MgOx films and atomic concentration were investigated by XRD and XPS, respectively. The Al-doped MgOx films showed set/reset resistance switching behavior at various Al doping concentrations. The process voltage of forming/set is decreased and whereas the initial current level is increased with decreasing thickness of Al-doped MgOx films. Besides, the initial current of Al-doped MgOx films is increased with increasing Al doping concentration in MgOx films. The change of resistance switching behavior depending on doping concentration was discussed in terms of concentration of non-lattice oxygen of Al-doped MgOx.

• Korean Journal of Materials Research
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• v.31 no.12
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• pp.727-731
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• 2021

In this study, we have investigated a selective emitter using a UV laser on BBr₃ diffusion doping layer. The selective emitter has two regions of high and low doping concentration alternatively and this structure can remove the disadvantages of homogeneous emitter doping. The selective emitters were fabricated by using UV laser of 355 nm on the homogeneous emitters which were formed on n-type Si by BBr₃ diffusion in the furnace and the heavy boron doping regions were formed on the laser regions. In the optimized laser doping process, we are able to achieve a highly concentrated emitter with a surface resistance of up to 43 Ω/□ from 105 ± 6 Ω/□ borosilicate glass (BSG) layer on Si. In order to compare the characteristics and confirm the passivation effect, the annealing is performed after Al₂O₃ deposition using an ALD. After the annealing, the selective emitter shows a better effect than the high concentration doped emitter and a level equivalent to that of the low concentration doped emitter.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.19 no.4
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• pp.903-908
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• 2015

This paper has analyzed threshold voltage shift for doping profile of asymmetric double gate(DG) MOSFET. Ion implantation is usually used in process of doping for semiconductor device and doping profile becomes Gaussian distribution. Gaussian distribution function is changed for projected range and standard projected deviation, and influenced on transport characteristics. Therefore, doping profile in channel of asymmetric DGMOSFET is affected in threshold voltage. Threshold voltage is minimum gate voltage to operate transistor, and defined as top gate voltage when drain current is $0.1{\mu}A$ per unit width. The analytical potential distribution of series form is derived from Poisson's equation to obtain threshold voltage. As a result, threshold voltage is greatly changed by doping profile in high doping range, and the shift of threshold voltage due to projected range and standard projected deviation significantly appears for bottom gate voltage in the region of high doping concentration.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.07a
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• pp.37-40
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• 2001

This paper presents the modeling methodology of Zinc diffusion process applied for high-speed avalanche photodiode fabrication using neural networks. Three process factors (sealing pressure, amount of Zn$_3$P$_2$ source per volume, and doping concentration of diffused layer) are examined by means of D-optimal design experiment. Then, diffusion rate and doping concentration of Zinc in diffused layer are characterized by a static response model generated by training fred-forward error back-propagation neural networks. It is observed that the process models developed here exhibit good agreement with experimental results.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.02a
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• pp.288-288
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• 2012

In this study, we investigated that the resistance switching characteristics of W-doped NbOx films with increasing W doping concentration. The W-doped NbOx based ReRAM devices with a TiN/W-doped NbOx/Pt/Ti/SiO2 were fabricated on Si substrates. The 50 nm thick W-doped NbOx films were deposited by reactive dc magnetron co-sputtering at $400^{\circ}C$ and oxygen partial pressure of 35%. Micro-structure of W-doped NbOx films and atomic concentration were investigated by XRD, TEM and XPS, respectively. The W-doped NbOx films showed set/reset resistance switching behavior at various W doping concentrations. The process voltage of set/reset is decreased and whereas the initial current level is increased with increasing W doping concentration in NbOx films. The change of resistance switching behavior depending on doping concentration was discussed in terms of concentration of metallic tungsten of oxygen of W-doped NbOx.

• Journal of Powder Materials
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• v.18 no.5
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• pp.401-405
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• 2011

Half-heusler phase ZrNiSn is one of the potential thermoelectric materials for high temperature application. In an attempt to investigate the effect of Sb doping on thermoelectric properties, half-heusler phase $ZrNiSn_{1-x}Sb_x$ ($0{\leq}x{\leq}0.08$) was synthesized by mechanical alloying of stoichiometric elemental powder compositions, and consolidated by vacuum hot pressing. Phase transformations during mechanical alloying and hot consolidation were investigated using XRD. Sb doped ZrNiSn was successfully produced in all doping ranges by vacuum hot pressing using as-milled powders without subsequent annealing. Thermoelectric properties as functions of temperature and Sb contents were evaluated for the hot pressed specimens. Sb doping up to x=0.04 in $ZrNiSn_{1-x}Sb_x$ was shown to be effective on thermoelectric properties and the figure of merit (ZT) was shown to reach to the maximum at x=0.02 in this study.

• 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.

• Proceeding of EDISON Challenge
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• 2013.04a
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• pp.266-268
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• 2013

In this paper, we study the channel doping concentration characteristics of junctionless nanowire transistors (JLT) using Edison nanowire FET device simulation. JLT has no junctions by very simple fabrication process. And this device has less variability and better electrical properties than classical inversion-mode transistors with PN junctions at the source and drain. In this simulation we use tri-gate structure. Source and drain doping concentration is $10^{20}atoms/cm^3$. The simulation results show that I-V characteristics of JLT change due to the variation of channel doping concentration.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.08a
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• pp.145.1-145.1
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• 2013

A prerequisite for the development of graphene-based field effect transistors (FETs) is reliable control of the type and concentration of carriers in graphene. These parameters can be manipulated via the deposition of atoms, molecules, and polymers onto graphene as a result of charge transfer that takes place between the graphene and adsorbates. In this work, we demonstrate a unique and facile methodology for the homogenous and stable p-type doping of graphene by hybridization with ZnO thin films fabricated by MeV electron beam irradiation (MEBI) under ambient conditions. The formation of the ZnO/graphene hybrid nanostructure was attributed to MEBI-stimulated dissociation of zinc acetate dihydrate and a subsequent oxidation process. A ZnO thin film with an ultra-flat surface and uniform thickness was formed on graphene. We found that homogeneous and stable p-type doping was achieved by charge transfer from the graphene to the ZnO film.