• Proceedings of the Korean Vacuum Society Conference
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• 2012.02a
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• pp.207-207
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• 2012

Si quantum dot (QD) imbedded in a $SiO_2$ matrix is a promising material for the next generation optoelectronic devices, such as solar cells and light emission diodes (LEDs). However, low conductivity of the Si quantum dot layer is a great hindrance for the performance of the Si QD-based optoelectronic devices. The effective doping of the Si QDs by semiconducting elements is one of the most important factors for the improvement of conductivity. High dielectric constant of the matrix material $SiO_2$ is an additional source of the low conductivity. Active doping of B was observed in nanometer silicon layers confined in $SiO_2$ layers by secondary ion mass spectrometry (SIMS) depth profiling analysis and confirmed by Hall effect measurements. The uniformly distributed boron atoms in the B-doped silicon layers of $[SiO_2(8nm)/B-doped\;Si(10nm)]_5$ films turned out to be segregated into the $Si/SiO_2$ interfaces and the Si bulk, forming a distinct bimodal distribution by annealing at high temperature. B atoms in the Si layers were found to preferentially substitute inactive three-fold Si atoms in the grain boundaries and then substitute the four-fold Si atoms to achieve electrically active doping. As a result, active doping of B is initiated at high doping concentrations above $1.1{\times}10^{20}atoms/cm^3$ and high active doping of $3{\times}10^{20}atoms/cm^3$ could be achieved. The active doping in ultra-thin Si layers were implemented to silicon quantum dots (QDs) to realize a Si QD solar cell. A high energy conversion efficiency of 13.4% was realized from a p-type Si QD solar cell with B concentration of $4{\times}1^{20}atoms/cm^3$. We will present the diffusion behaviors of the various dopants in silicon nanostructures and the performance of the Si quantum dot solar cell with the optimized structures.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09b
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• pp.1241-1242
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• 2006

Electromagnetic properties of $CeO_2$ doped and undoped YBaCuO superconductors were evaluated to investigate the effect of pinning center on the magnetization and magnetic shielding. The variation $\DeltaM$ with doping was maximum for 3% doping and decrease with further doping. The magnetic shielding was evaluated by measuring the induced voltage in secondary coil and the voltage initially set to 0.5V, decreased to 0.17V and 0.28V respectively for the undoped and 3% $CeO_2$ doped sample. The much less change in the induced voltage for the 3% doped sample is attributed to the increased flux shielding by shielding vortex current. The $CeO_2$ was converted to fine $BaCeO_3$ particles which were trapped in YBaCuO superconductor during the reaction sintering. The trapped fine particles, $BaCeO_3$ may be acted as a flux pinning center.

• Journal of the Korean Vacuum Society
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• v.22 no.5
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• pp.238-244
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• 2013

Doping process using laser is an important process in fabrication of solar cell for heat treatment. However, the process of using the furnace is difficult to form a selective emitter doping region. The case of using a selective emitter laser doping is required an expensive laser equipment and induce the wafer's structure damage due to high temperature. This study, we fabricated a new costly plasma source. Through this, we research the selective emitter doping. We fabricated that the atmospheric pressure plasma jet injected Ar gas is inputted a low frequency (a few tens kHz). We used shallow doping wafers existing PSG (Phosphorus Silicate Glass) on the shallow doping CZ P-type wafer. Atmospheric plasma treatment time was 15 s and 30 s, and current for making the plasma is 40 mA and 70 mA. We investigated a doping profile by using SIMS (Secondary Ion Mass Spectroscopy) and we grasp the sheet resistance of electrical character by using doping profile. As result of experiment, prolonged doping process time and highly plasma current occur a deeper doping depth, moreover improve sheet resistance. We grasped the wafer's surface damage after atmospheric pressure plasma doping by using SEM (Scanning Electron Microscopy). We check that wafer's surface is not changed after plasma doping and atmospheric pressure doping width is broaden by increase of plasma treatment time and current.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.08a
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• pp.232-232
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• 2012

The doping of semiconducting elements is essential for the development of silicon quantum dot (QD) solar cells. Especially the doping elements should be activated by substitution at the crystalline sites in the crystalline silicon QDs. However, no analysis technique has been developed for the analysis of the activated dopants in silicon QDs in $SiO_2$ matrix. Secondary ion mass spectrometry (SIMS) is a powerful technique for the in-depth analysis of solid materials and the impurities analysis of boron and phosphorus in semiconductor materials. For the study of diffusion behaviour of B and P by SIMS, Si/$SiO_2$ multilayer films doped by B or P were fabricated and annealed at high temperatures for the activated doping of B and P. The distributions of doping elements were analyzed by SIMS. Boron found to be preferentially distributed in Si layer rather than the $SiO_2$ layer. Especially the B in the Si layers was separated to two components of an interfacial component and a central one. The central component was understood as the activated elements. On the other hand, phosphorus did not show any preferred diffusion.

• Korean Journal of Materials Research
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• v.28 no.10
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• pp.564-569
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• 2018

$Cu_2ZnSn(S,Se)_4$ (CZTSSe) films were prepared on Mo coated soda lime glass substrates by sulfo-selenization of sputtered stacked Zn-Sn-Cu(CZT) precursor films. The precursor was dried in a capped state with aqueous NaOH solution. The CZT precursor films were sulfo-selenized in the S + Se vapor atmosphere. Sodium was doped during the sulfo-selenization treatment. The effect of sodium doping on the structural and electrical properties of the CZTSSe thin films were studied using FE-SEM(field-emission scanning electron microscopy), XRD(X-ray diffraction), XRF(X-ray fluorescence spectroscopy), dark current, SIMS(secondary ion mass spectrometry), conversion efficiency. The XRD, XRF, FE-SEM, Dark current, SIMS and cell efficiency results indicated that the properties of sulfo-selenized CZTSSe thin films were strongly related to the sodium doping. Further detailed analysis and discussion for effect of sodium doping on the properties CZTSSe thin films will be discussed.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.27 no.6
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• pp.95-99
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• 2013

Furnace is currently the most important doping process using POCl3 in solar cell. However furnace need an expensive equipment cost and it has to purge a poisonous gas. Moreover, furnace typically difficult appling for selective emitters. In this study, we developed a new atmospheric pressure plasma source, in this procedure, we research the atmospheric pressure plasma doping that dopant is phosphoric acid($H_3PO_4$). Metal tube injected Ar gas was inputted 5 kV of a low frequency(scores of kHz) induced inverter, so plasma discharged at metal tube. We used the P type silicon wafer of solar cell. We regulated phosphoric acid($H_3PO_4$) concentration on 10% and plasma treatment time is 90 s, 150 s, we experiment that plasma current is 70 mA. We check the doping depth that 287 nm at 90 s and 621 nm at 150 s. We analysis and measurement the doping profile by using SIMS(Secondary Ion Mass Spectroscopy). We calculate and grasp the sheet resistance using conventional sheet resistance formula, so there are 240 Ohm/sq at 90 s and 212 Ohm/sq at 150 s. We analysis oxygen and nitrogen profile of concentration compared with furnace to check the doped defect of atmosphere.

• 한국전기화학회:학술대회논문집
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• 2001.04a
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• pp.54-54
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• 2001

• Analytical Science and Technology
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• v.8 no.4
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• pp.583-590
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• 1995

Pitch-based mesophase carbon fibers prepared at different temperatures were heat-treated at temperatures lower than those of the preparation and the electrochemical Li doping/undoping characteristics were evaluated in relation to the data of IR, mass, etc. Presence of surface hydroxyls were confirmed by FTIR for lower temperature sample which showed poor anode characteristics. Upon oxidative heating, removal of surface hydroxyls took place, resulting in a remarkable improvement of the electrode characteristics. At the same time, surface roughening took place, which was confirmed by SEM and double layer capacity measurements. In situ mass spectra obesrved during the heat-treatments showed gas evolution of $H_2O$, CO, $CO_2$, $C_2H_4$, and/or $H_2$ depending on the conditions. These data together with those of weight loss and conductivity provided us a valuable information in regard to the evaluation of the electrochemical characteristics.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.35 no.4
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• pp.407-411
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• 2022

Bulk-sized PbTiO₃ (PT), which is widely known as a high-performance ferroelectric oxide but cannot be fabricated into a monolithic ceramic due to its high c/a ratio, was successfully prepared with a high tetragonality by partially substituting Ni ions for Pb ions using a solid-state reaction method. We found that Ni-doped PT was well-fabricated as a bulk monolith with a significant c/a ratio of ~1.06. X-ray diffraction on as-sintered and crushed samples revealed that NiTiO₃ secondary phase was present at the doping level of more than 2 at.%. Scanning electron microscopic study showed that NiTiO₃ secondary phase grew on the surface of PT specimens regardless of the doping level possibly due to the evaporation of Pb during sintering. We demonstrated that an unconventional introduction of Ni ions into A-site plays a key role on the fabrication of bulk PT, though how Ni ion functions should be studied further. We expect that this study contributes to a further development of displacive ferroelectric oxides with a high c/a ratio.

• Journal of the Korean Vacuum Society
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• v.10 no.1
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• pp.104-111
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• 2001

B-doped hydrogenated amorphous silicon carbide (a-SiC:H) thin films were prepared by plasma-enhanced chemical-vapor deposition in a gas mixture of $SiH_4, CH_4,\;and\; B_2H_6$. Physical and chemical properties of a-SiC:H films grown with varing the ratio of $B_2H_6/(SiH_4+CH_4)$ were characterized with various analysis methods including scanning electron microscopy (SEM), X-ray diffractometry (XRD), Raman spectroscopy, Fourier-transform infrared (FTIR) spectroscopy, secondary ion mass spectroscopy (SIMS), UV absorption CH_4spectroscopy and electrical conductivity measurements. With the B-doping concentration, the doping efficiency and the micro-crystallinity were decreased and the film became amorphous when $B_2H_6/(SiH_4{plus}CH_4)$ was over $5{\times}10^{-3}$. The addition of $B_2H_6$ gas during deposition decreased the H content in the film by lowering the quantity of Si-C-H bonds. Consequently, the optical band gap and the activation energy of a-SiC:H films were decreased with increasing the B-doping level.