• Current Photovoltaic Research
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• v.4 no.2
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• pp.54-58
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• 2016

Laser-doped selective emitter process requires dopant source deposition, spin-on-glass, and is able to form selective emitter through SiNx layer by laser irradiation on desired locations. However, after laser doping process, the remaining dopant layer needs to be washed out. Laser-induced melting of pre-deposited impurity doping is a precise selective doping method minimizing addition of process steps. In this study, we introduce a novel scheme for fabricating highly efficient selective emitter solar cell by laser doping. During this process, laser induced damage induces front contact destabilization due to the hindrance of silver nucleation even though laser doping has a potential of commercialization with simple process concept. When the laser induced damage is effectively removed using solution etch back process, the disadvantage of laser doping was effectively removed. The devices fabricated using laser doping scheme power conversion efficiency was significantly improved about 1% abs. after removal the laser damages.

• 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.

• Proceedings of the Korean Vacuum Society Conference
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• 2010.02a
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• pp.322-322
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• 2010

For boron doping on n-type silicon wafer, around $1,000^{\circ}C$ doping temperature is required, because of the relatively low solubility of boron in a crystalline silicon comparing to the phosphorus case. Boron doping by fiber laser annealing and lamp furnace heat treatment were carried out for the uniformly deposited p-a-Si:H layer. Since the uniformly deposited p-a-Si:H layer by cluster is highly needed to be doped with high temperature heat treatment. Amorphous silicon layer absorption range for fiber laser did not match well to be directly annealed. To improve the annealing effect, we introduce additional lamp furnace heat treatment. For p-a-Si:H layer with the ratio of $SiH_4:B_2H_6:H_2$=30:30:120, at $200^{\circ}C$, 50 W power, 0.2 Torr for 30 min. $20\;mm\;{\times}\;20\;mm$ size fiber laser cut wafers were activated by Q-switched fiber laser (1,064 nm) with different sets of power levels and periods, and for the lamp furnace annealing, $980^{\circ}C$ for 30 min heat treatment were implemented. To make the sheet resistance expectable and uniform as important processes for the $p^+$ layer on a polished n-type silicon wafer of (100) plane, the Q-switched fiber laser used. In consequence of comparing the results of lifetime measurement and sheet resistance relation, the fiber laser treatment showed the trade-offs between the lifetime and the sheet resistance as $100\;{\omega}/sq.$ and $11.8\;{\mu}s$ vs. $17\;{\omega}/sq.$ and $8.2\;{\mu}s$. Diode level device was made to confirm the electrical properties of these experimental results by measuring C-V(-F), I-V(-T) characteristics. Uniform and expectable boron heavy doped layers by fiber laser and lamp furnace are not only basic and essential conditions for the n-type crystalline silicon solar cell fabrication processes, but also the controllable doping concentration and depth can be established according to the deposition conditions of layers.

• Electrical & Electronic Materials
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• v.11 no.11
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• pp.22-27
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• 1998

We have investigated the effect of an ion shower doping of the laser annealed poly-Si films at an elevated substrate temperatures. The substrate temperature was varied from room temperature to 300$^{\circ}C$ when the poly-Si film was doped with phosphorus by a non-mass-separated ion shower. Optical, structural, and electrical characterizations have been performed in order to study the effect of the ion showering doping. The sheet resistance of the doped poly-Si films was decreased from7${\times}$106 $\Omega$/$\square$ to 700 $\Omega$/$\square$ when the substrate temperature was increased from room temperature to 300$^{\circ}C$. This low sheet resistance is due to the fact that the doped film doesn't become amorphous but remains in the polycrystalline phase. The mildly elevated substrate temperature appears to reduce ion damages incurred in poly-Si films during ion-shower doping. Using the ion-shower doping at 250$^{\circ}C$, the field effect mobility of 120 $\textrm{cm}^2$/(v$.$s) has been obtained for the n-channel poly-Si TFTs.

• New & Renewable Energy
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• v.9 no.2
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• pp.23-29
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• 2013

Furnace and laser is currently the most important doping process. However furnace is typically difficult appling for selective emitters. Laser requires an expensive equipment and induces a structural damage due to high temperature using laser. This study has developed a new atmospheric pressure plasma source and research atmospheric pressure plasma doping. Atmospheric pressure plasma source injected Ar gas is applied a low frequency (a few 10 kHz) and discharged the plasma. We used P type silicon wafers of solar cell. We set the doping parameter that plasma treatment time was 6s and 30s, and the current of making the plasma is 70 mA and 120 mA. As result of experiment, prolonged plasma process time and highly plasma current occur deeper doping depth and improve sheet resistance. We investigated doping profile of phosphorus paste by SIMS (Secondary Ion Mass Spectroscopy) and obtained the sheet resistance using generally formula. Additionally, grasped the wafer surface image with SEM (Scanning Electron Microscopy) to investigate surface damage of doped wafer. Therefore we confirm the possibility making the selective emitter of solar cell applied atmospheric pressure plasma doping with phosphorus paste.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.06a
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• pp.456-456
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• 2009

Boron doping on an n-type Si wafer is requisite process for IBC (Interdigitated Back Contact) solar cells. Fiber laser annealing is one of boron doping methods. For the boron doping, uniformly coated or deposited film is highly required. Plasma enhanced chemical vapor deposition (PECVD) method provides a uniform dopant film or layer which can facilitate doping. Because amorphous silicon layer absorption range for the wavelength of fiber laser does not match well for the direct annealing. In this study, to enhance thermal affection on the existing p-a-Si:H layer, a ${\mu}c$-Si:H intrinsic layer was deposited on the p-a-Si:H layer additionally by PECVD. To improve heat transfer rate to the amorphous silicon layer, and as heating both sides and protecting boron eliminating from the amorphous silicon layer. For p-a-Si:H layer with the ratio of $SiH_4$ : $B_2H_6$ : $H_2$ = 30 : 30 : 120, at $200^{\circ}C$, 50 W, 0.2 Torr for 30 minutes, and for ${\mu}c$-Si:H intrinsic layer, $SiH_4$ : $H_2$ = 10 : 300, at $200^{\circ}C$, 30 W, 0.5 Torr for 60 minutes, 2 cm $\times$ 2 cm size wafers were used. In consequence of comparing the results of lifetime measurement and sheet resistance relation, the laser condition set of 20 ~ 27 % of power, 150 ~ 160 kHz, 20 ~ 50 mm/s of marking speed, and $10\;{\sim}\;50 {\mu}m$ spacing with continuous wave mode of scanner lens showed the correlation between lifetime and sheet resistance as $100\;{\Omega}/sq$ and $11.8\;{\mu}s$ vs. $17\;{\Omega}/sq$ and $8.2\;{\mu}s$. Comparing to the singly deposited p-a-Si:H layer case, the additional ${\mu}c$-Si:H layer for doping resulted in no trade-offs, but showed slight improvement of both lifetime and sheet resistance, however sheet resistance might be confined by the additional intrinsic layer. This might come from the ineffective crystallization of amorphous silicon layer. For the additional layer case, lifetime and sheet resistance were measured as $84.8\;{\Omega}/sq$ and $11.09\;{\mu}s$ vs. $79.8\;{\Omega}/sq$ and $11.93\;{\mu}s$. The co-existence of $n^+$layeronthesamesurfaceandeliminating the laser damage should be taken into account for an IBC solar cell structure. Heavily doped uniform boron layer by fiber laser brings not only basic and essential conditions for the beginning step of IBC solar cell fabrication processes, but also the controllable doping concentration and depth that can be established according to the deposition conditions of layers.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.06a
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• pp.5-5
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• 2008

We design and demonstrate the controled doping into ZnO nanowires (NWs) adopting self-contrived hot-walled pulsed laser deposition (HW-PLD). Optimized synthesis conditions with the diversified dopants guarantee the excellent crystalinity and morphology as well as electrical properties of the NWs. Proprietary target rotating system in the HW-PLD fuels the controlled formation and doping of the NWs. Prepared NWs sensitive to the environment are systematically characterized, and the doping mechanism is discussed.

• Journal of the Korean Ceramic Society
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• v.37 no.1
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• pp.33-43
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• 2000

Up-conversion of rare-earth element added glass is promising area for short wavelength laser source by utilizing high power semiconductor infra-red laser if the efficiency can be increased by proper method. In this study, relatively low phonon energy fluoride glasses were prepared by co-doping rare-earth elements to realize the high efficiency up-convertor. The physical, chemical, andoptical properties of co-doped fluoride glasses were measured. 10 combinations of 5 different rare-earth fluoride elements doped samples were prepared and their transition temperatures, chemical durability, density, hardness, refractive index, absorption, fluorescence, and fluorescence lifetime were measured. 480nm wavelengths blue up-conversion was found in the Yb3+/Tm3+ co-doped glass sample with 800nm laser source and the optimum composition for the most efficient blue up-conversion was found from the glass sample with 0.3 mol% TmF3 and 1 mol% YbF3.

• Current Photovoltaic Research
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• v.2 no.3
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• pp.120-123
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• 2014

Thermal doping method using furnace is generally used for solar-cell wafer doping. It takes a lot of time and high cost and use toxic gas. Generally selective emitter doping using laser, but laser is very high equipment and induce the wafer's structure damage. In this study, we apply atmospheric pressure plasma for solar-cell wafer doping. We fabricated that the atmospheric pressure plasma jet injected Ar gas is inputted a low frequency (1 kHz ~ 100 kHz). We used shallow doping wafers existing PSG (Phosphorus Silicate Glass) on the shallow doping CZ P-type wafer (120 ohm/square). SIMS (Secondary Ion Mass Spectroscopy) are used for measuring wafer doping depth and concentration of phosphorus. 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 Institute of Electrical and Electronic Material Engineers Conference
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• 2009.06a
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• pp.69-69
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• 2009

In other to progress better crystallization transition and long phase-transformation data of phase-change memory (PRAM), we investigated about the effect of Sb doping and Ag ions percolating into Ge-Se-Te phase-change material. Doped Sb concentrations was determined each of 10 wt%, 20 wt% and 30 wt%. As the Sb-doping concentration was increased, the resistivity decreased and the crystallization temperature increased. Ionization of Ag was progressed by DPSS laser (532 nm) for 1 hour. The resistivity was more decreased and the crystallization temperature was more increased in case of adding Ag layer under Sh-(Ge-Se-Te) thin film. At the every condition of thin films included Ag layer more stable states were indicated compare with just Sh-doped Ge-Se-Te thin films.