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Inhibiting charge recombination effectively by surface passivation is very important for high-efficiency silicon solar cells. As passivated emitter and rear cells (PERC), which surpass conventional solar cells, have emerged, the need for novel passivation scheme is increasing. Passivation layer stacks using negatively charged Al2O3 have been applied successfully to realize high-efficiency PERC solar cells. This paper reviews the developments of surface passivation by Al2O3/TiO2-based layers. Topics range from synthesis methods and optical properties as anti-reflection coatings to the electrical properties related to the material, interface and passivation quality. Ultrathin Al2O3/TiO2-based layers generally feature a combination of field-effect passivation by negative fixed charges, a low interface defect density, and adequate humidity stability. Among the various deposition methods, this review focuses on atomic layer deposition, which can form dual layers and nanolaminates. This paper discusses how the features of atomic-layer-deposited Al2O3/TiO2-based layers can be utilized for interface engineering and tailoring the properties of surface passivation schemes.
Dongchul Suh. Status of Al 2 O 3 /TiO 2 ‐Based Antireflection and Surface Passivation for Silicon Solar Cells. physica status solidi (RRL) – Rapid Research Letters 2021, 1 .
AMA StyleDongchul Suh. Status of Al 2 O 3 /TiO 2 ‐Based Antireflection and Surface Passivation for Silicon Solar Cells. physica status solidi (RRL) – Rapid Research Letters. 2021; ():1.
Chicago/Turabian StyleDongchul Suh. 2021. "Status of Al 2 O 3 /TiO 2 ‐Based Antireflection and Surface Passivation for Silicon Solar Cells." physica status solidi (RRL) – Rapid Research Letters , no. : 1.
Chemical processes are very important for the development of high-efficiency crystalline solar cells, mainly for surface texturing to improve light absorption and cleaning processes to reduce surface recombination. Recently, research has been focusing on the impact of chemical polishing on the performance of a passivated emitter and rear cells (PERC), with particular emphasis on the dielectric passivation layers on the front side. This study examined the influence of etching on the passivation of Al2O3/TiO2 stacks, where the films may each be deposited using a range of deposition and post-annealing parameters. Most TiO2 films deposited at 300 °C were resistant to chemical etching, and higher temperature deposition and annealing produced more chemical-resistant films. TiO2 films deposited at 100 °C were etched slightly by SC1 and SC2 solutions at room temperature, whereas they were etched at a relatively high rate in an HF solution, even when capped with a thick TiO2 layer (up to 50 nm in thickness); blistering occurred in 20-nm-thick Al2O3 films. In contrast to the as-deposited films, the annealed films showed a lower level of passivation as 1% HF etching proceeded. The implied open circuit voltage of the samples annealed at 300 °C after HF etching decreased more than those annealed at 400 °C. The dark area in the photoluminescence images was not resistant to the HF solution and showed more etch pits. The etching strategies developed in this study are expected to help setup integration processes and increase the applicability of this stack to solar cells.
Dongchul Suh. Etch Characteristics and Morphology of Al2O3/TiO2 Stacks for Silicon Surface Passivation. Sustainability 2019, 11, 3857 .
AMA StyleDongchul Suh. Etch Characteristics and Morphology of Al2O3/TiO2 Stacks for Silicon Surface Passivation. Sustainability. 2019; 11 (14):3857.
Chicago/Turabian StyleDongchul Suh. 2019. "Etch Characteristics and Morphology of Al2O3/TiO2 Stacks for Silicon Surface Passivation." Sustainability 11, no. 14: 3857.
Commercializing a highly efficient passivated-emitter-and-rear-cell solar cell requires high passivation quality and stability of the cell's Al2O3 layer. This paper reports on light-induced degradation (LID) of the Al2O3 layer and the effects of post-annealing temperatures after light soaking on the passivation quality. To understand the LID phenomenon of the Al2O3 passivation layer, we used a Ga-doped Si wafer that prevented boron-oxygen LID effects. The fabrication process was carried out on large-area (156 × 156 mm2), commercially available, (100)-oriented Ga-doped Czochralski(Cz) Si wafers in the pilot line. Before and after light soaking, the effective lifetime was measured using Sinton's quasi-steady-state photoconductance as a function of annealing temperature. Chemical binding structures near the interface of the Al2O3 film and Si wafer were investigated using X-ray photoelectron spectroscopy (XPS). The passivation quality and light-induced degradation showed the best performance at an annealing temperature of 600°C. Analysis of XPS data revealed that the chemical binding structures at the interface of the Al2O3 layer and Si wafer were stabilized by optimizing the annealing condition of the Al2O3 layer. By optimizing an industrially feasible Al2O3 passivation process, an efficiency of 20.1% was achieved on large-area, commercial-grade Cz c-Si wafers.
Chan Bin Mo; Sungeun Park; Soohyun Bae; Se Jin Park; Young-Su Kim; JungYup Yang; Hyunjong Kim; Dongchul Suh; Yoonmook Kang. Minimizing Light-Induced Degradation of the Al2O3Rear Passivation Layer for Highly Efficient PERC Solar Cells. ECS Journal of Solid State Science and Technology 2018, 7, Q253 -Q258.
AMA StyleChan Bin Mo, Sungeun Park, Soohyun Bae, Se Jin Park, Young-Su Kim, JungYup Yang, Hyunjong Kim, Dongchul Suh, Yoonmook Kang. Minimizing Light-Induced Degradation of the Al2O3Rear Passivation Layer for Highly Efficient PERC Solar Cells. ECS Journal of Solid State Science and Technology. 2018; 7 (12):Q253-Q258.
Chicago/Turabian StyleChan Bin Mo; Sungeun Park; Soohyun Bae; Se Jin Park; Young-Su Kim; JungYup Yang; Hyunjong Kim; Dongchul Suh; Yoonmook Kang. 2018. "Minimizing Light-Induced Degradation of the Al2O3Rear Passivation Layer for Highly Efficient PERC Solar Cells." ECS Journal of Solid State Science and Technology 7, no. 12: Q253-Q258.
Boron-diffused samples passivated by Al2O3/TiO2 stacks with different types of TiO2 were investigated. An emitter saturation current density of 11 × 10−15 A/cm2 was obtained for Al2O3/TiO2 passivated samples with symmetrical 100 Ω/sq. boron diffusion. The surface passivation of Al2O3/TiO2 stacks was strongly impacted by the temperature, gas, and sequence during two-step annealing. In addition, the saturation current density of the Al2O3/TiO2 stacks is influenced by the TiO2 layers with an O3 treatment. Enhanced passivation performance of the Al2O3/TiO2 stacks was achieved by a combination of appropriate TiO2 capping layer and post-annealing. The results of this study provide reliable criteria for the design of thermally-stable Al2O3/TiO2 stacks on high-efficiency silicon solar cells.
Dongchul Suh. Thermal stability of Al2O3/TiO2 stacks for boron emitter passivation on n-type silicon solar cells. Thin Solid Films 2018, 669, 60 -64.
AMA StyleDongchul Suh. Thermal stability of Al2O3/TiO2 stacks for boron emitter passivation on n-type silicon solar cells. Thin Solid Films. 2018; 669 ():60-64.
Chicago/Turabian StyleDongchul Suh. 2018. "Thermal stability of Al2O3/TiO2 stacks for boron emitter passivation on n-type silicon solar cells." Thin Solid Films 669, no. : 60-64.
The characteristics of laser ablation prepared on the structures of a passivated emitter and rear cell (PERC) using additional laser irradiation were investigated. Particular emphasis was placed on the distribution of laser damage and contact geometry on the cell performance. The residual Al2O3 passivation layer of the Al2O3/SiNx passivated samples was removed almost completely by three laser shots. No severe damage profile was observed near the silicon surface, but damage profiles with a thickness of 10–15 nm were observed in the form of amorphous silicon. Additional laser irradiation after contact opening generally degraded the passivation quality with increasing laser shots, and the depth of laser-induced damage was a few micrometers. Interestingly, the PERC cells fabricated using three laser shots had higher efficiency than that produced by one laser shot. This was attributed to the chemical reaction between the silicon and Al paste, resulting in a eutectic alloy and back surface field, which was much thicker than the depth of laser damage. Consequently, the laser damage by the ablation process can be recovered by metallization during the fabrication of PERC cells. The experimental analyses highlighted that the fraction of point contact is a fundamental parameter in the design of PERC cells. The reduction of fraction of point contacts to reduce the recombination losses at rear surface led to an increase of series resistance. Therefore it is necessary to optimize the width and pitch of point contacts for high-efficiency solar cells.
Dongchul Suh. Influence of laser damage and contact geometry on the performance of passivated emitter and rear cell solar cells. Thin Solid Films 2018, 668, 45 -49.
AMA StyleDongchul Suh. Influence of laser damage and contact geometry on the performance of passivated emitter and rear cell solar cells. Thin Solid Films. 2018; 668 ():45-49.
Chicago/Turabian StyleDongchul Suh. 2018. "Influence of laser damage and contact geometry on the performance of passivated emitter and rear cell solar cells." Thin Solid Films 668, no. : 45-49.
Sungeun Park; Hyomin Park; Dongseop Kim; JungYup Yang; Dongho Lee; Young-Su Kim; Hyun-Jong Kim; Dongchul Suh; Byoung Koun Min; Kyung Nam Kim; Se Jin Park; Donghwan Kim; Hae-Seok Lee; Junggyu Nam; Yoonmook Kang. Correction to: Optimization of Controllable Factors in the Aluminum Silicon Eutectic Paste and Rear Silicon Nitride Mono-Passivation Layer of PERC Solar Cells. Metals and Materials International 2018, 24, 1192 -1192.
AMA StyleSungeun Park, Hyomin Park, Dongseop Kim, JungYup Yang, Dongho Lee, Young-Su Kim, Hyun-Jong Kim, Dongchul Suh, Byoung Koun Min, Kyung Nam Kim, Se Jin Park, Donghwan Kim, Hae-Seok Lee, Junggyu Nam, Yoonmook Kang. Correction to: Optimization of Controllable Factors in the Aluminum Silicon Eutectic Paste and Rear Silicon Nitride Mono-Passivation Layer of PERC Solar Cells. Metals and Materials International. 2018; 24 (5):1192-1192.
Chicago/Turabian StyleSungeun Park; Hyomin Park; Dongseop Kim; JungYup Yang; Dongho Lee; Young-Su Kim; Hyun-Jong Kim; Dongchul Suh; Byoung Koun Min; Kyung Nam Kim; Se Jin Park; Donghwan Kim; Hae-Seok Lee; Junggyu Nam; Yoonmook Kang. 2018. "Correction to: Optimization of Controllable Factors in the Aluminum Silicon Eutectic Paste and Rear Silicon Nitride Mono-Passivation Layer of PERC Solar Cells." Metals and Materials International 24, no. 5: 1192-1192.
The back-contact crystalline solar cell features a design in which the positive emitter and negative back surface field are both located on the rear surface. The obvious benefit of this design is that efficiency can be improved by eliminating shading from the front metal grid. However, fabricating devices with the conventional back contact configuration requires costly patterning. The high manufacturing costs and complexity of the patterning process has been a barrier in preventing the solar cell industry from adopting the back-contact design despite it having the highest conversion efficiency. To reduce costs and the number of processes, we fabricated interdigitated back-contact solar cells using an ion implantation process with a shadow mask instead of the conventional patterning and diffusion process, and achieved a 22.9% conversion efficiency. To analyze the cost-performance of ion implantation process, we developed a bottom-up cost model involving five categories: depreciation expenses, materials, labor, utility, and maintenance costs assuming a production of 300 MW/year. The reduction in process steps using ion implantation substantially decreased the initial capital expenses. This impacted the overall cost structure and reduced the cell processing costs by 20% compared to conventional back-contact solar cells.
Jungho Song; Chanbin Mo; Dongseop Kim; Junggyu Nam; Jung Yup Yang; Dongchul Suh; Hyomin Park; Soohyun Bae; Se Jin Park; Sungeun Park; Hae-Seok Lee; Young-Su Kim; Yoonmook Kang; Donghwan Kim. Cost-Performance Analysis for Interdigitated Back-Contact Solar Cells Using Ion Implantation Process. Nanoscience and Nanotechnology Letters 2018, 10, 548 -553.
AMA StyleJungho Song, Chanbin Mo, Dongseop Kim, Junggyu Nam, Jung Yup Yang, Dongchul Suh, Hyomin Park, Soohyun Bae, Se Jin Park, Sungeun Park, Hae-Seok Lee, Young-Su Kim, Yoonmook Kang, Donghwan Kim. Cost-Performance Analysis for Interdigitated Back-Contact Solar Cells Using Ion Implantation Process. Nanoscience and Nanotechnology Letters. 2018; 10 (4):548-553.
Chicago/Turabian StyleJungho Song; Chanbin Mo; Dongseop Kim; Junggyu Nam; Jung Yup Yang; Dongchul Suh; Hyomin Park; Soohyun Bae; Se Jin Park; Sungeun Park; Hae-Seok Lee; Young-Su Kim; Yoonmook Kang; Donghwan Kim. 2018. "Cost-Performance Analysis for Interdigitated Back-Contact Solar Cells Using Ion Implantation Process." Nanoscience and Nanotechnology Letters 10, no. 4: 548-553.
Dongchul Suh. Efficient implementation of multiple drive-in steps in thermal diffusion of phosphorus for PERC solar cells. Current Applied Physics 2018, 18, 178 -182.
AMA StyleDongchul Suh. Efficient implementation of multiple drive-in steps in thermal diffusion of phosphorus for PERC solar cells. Current Applied Physics. 2018; 18 (2):178-182.
Chicago/Turabian StyleDongchul Suh. 2018. "Efficient implementation of multiple drive-in steps in thermal diffusion of phosphorus for PERC solar cells." Current Applied Physics 18, no. 2: 178-182.
Al2O3/TiO2 stacks formed by atomic layer deposition are known to provide a high level of passivation for boron-doped silicon. In previous works, the TiO2 layer was deposited on a pre-annealed Al2O3 layer, however this stack showed passivation degradation after post-deposition annealing. This work presents an alternative to using the as-deposited Al2O3 for the Al2O3/TiO2 stack, which shows no degradation of passivation after post-deposition annealing up to 400 °C. This approach simplifies the processing, allowing continuous layer deposition, and eliminates the undesirable vacuum breaking. This simplified processing leads to better thermal stability of the Al2O3/TiO2 stacks and a low emitter saturation current density. In order to understand the underlying mechanism of surface passivation, an investigation on the effect of thermal SiO2 on the passivation of the Al2O3/TiO2 stack was performed, which indicates that the TiO2 capping layer enhances the field-effect passivation for both the Si/Al2O3 and SiO2/Al2O3 structures.
Dongchul Suh; Yoonmook Kang. Facile and Thermally-Stable Al2O3 Passivation by Using In-Situ TiO2 as a Capping Layer for Boron Emitter of N-Type Silicon. Journal of Nanoscience and Nanotechnology 2017, 17, 5003 -5007.
AMA StyleDongchul Suh, Yoonmook Kang. Facile and Thermally-Stable Al2O3 Passivation by Using In-Situ TiO2 as a Capping Layer for Boron Emitter of N-Type Silicon. Journal of Nanoscience and Nanotechnology. 2017; 17 (7):5003-5007.
Chicago/Turabian StyleDongchul Suh; Yoonmook Kang. 2017. "Facile and Thermally-Stable Al2O3 Passivation by Using In-Situ TiO2 as a Capping Layer for Boron Emitter of N-Type Silicon." Journal of Nanoscience and Nanotechnology 17, no. 7: 5003-5007.
Gapless interdigitated back contact (IBC) solar cells were fabricated with phosphorous back surface field on a boron emitter, using an ion implantation process. Boron emitter (boron ion implantation) is counter doped by the phosphorus back surface field (BSF) (phosphorus ion implantation) without gap. The gapless process step between the emitter and BSF was compared to existing IBC solar cell with gaps between emitters and BSFs obtained using diffusion processes. We optimized the doping process in the phosphorous BSF and boron emitter region, and the implied Voc and contact resistance relationship of the phosphorous and boron implantation dose in the counter doped region was analyzed. We confirmed the shunt resistance of the gapless IBC solar cells and the possibility of shunt behavior in gapless IBC solar cells. The highly doped counter doped BSF led to a controlled junction breakdown at high reverse bias voltages of around 7.5 V. After the doping region was optimized with the counter doped BSF and emitter, a large‐area (5 inch pseudo square) gapless IBC solar cell with a power conversion efficiency of 22.9% was made.
Young-Su Kim; Chanbin Mo; Doo Youl Lee; Sung Chan Park; Dongseop Kim; Junggyu Nam; JungYup Yang; Dongchul Suh; Hyun-Jong Kim; Hyomin Park; Se Jin Park; Donghwan Kim; Jungho Song; Hae-Seok Lee; Sungeun Park; Yoonmook Kang. Gapless point back surface field for the counter doping of large-area interdigitated back contact solar cells using a blanket shadow mask implantation process. Progress in Photovoltaics: Research and Applications 2017, 25, 989 -995.
AMA StyleYoung-Su Kim, Chanbin Mo, Doo Youl Lee, Sung Chan Park, Dongseop Kim, Junggyu Nam, JungYup Yang, Dongchul Suh, Hyun-Jong Kim, Hyomin Park, Se Jin Park, Donghwan Kim, Jungho Song, Hae-Seok Lee, Sungeun Park, Yoonmook Kang. Gapless point back surface field for the counter doping of large-area interdigitated back contact solar cells using a blanket shadow mask implantation process. Progress in Photovoltaics: Research and Applications. 2017; 25 (12):989-995.
Chicago/Turabian StyleYoung-Su Kim; Chanbin Mo; Doo Youl Lee; Sung Chan Park; Dongseop Kim; Junggyu Nam; JungYup Yang; Dongchul Suh; Hyun-Jong Kim; Hyomin Park; Se Jin Park; Donghwan Kim; Jungho Song; Hae-Seok Lee; Sungeun Park; Yoonmook Kang. 2017. "Gapless point back surface field for the counter doping of large-area interdigitated back contact solar cells using a blanket shadow mask implantation process." Progress in Photovoltaics: Research and Applications 25, no. 12: 989-995.
Sungeun Park; Hyomin Park; Dongseop Kim; Junggyu Nam; JungYup Yang; Dongho Lee; Byoung Koun Min; Kyung Nam Kim; Se Jin Park; Seongtak Kim; Dongchul Suh; Donghwan Kim; Hae-Seok Lee; Yoonmook Kang. Continuously deposited anti-reflection double layer of silicon nitride and silicon oxynitride for selective emitter solar cells by PECVD. Current Applied Physics 2017, 17, 517 -521.
AMA StyleSungeun Park, Hyomin Park, Dongseop Kim, Junggyu Nam, JungYup Yang, Dongho Lee, Byoung Koun Min, Kyung Nam Kim, Se Jin Park, Seongtak Kim, Dongchul Suh, Donghwan Kim, Hae-Seok Lee, Yoonmook Kang. Continuously deposited anti-reflection double layer of silicon nitride and silicon oxynitride for selective emitter solar cells by PECVD. Current Applied Physics. 2017; 17 (4):517-521.
Chicago/Turabian StyleSungeun Park; Hyomin Park; Dongseop Kim; Junggyu Nam; JungYup Yang; Dongho Lee; Byoung Koun Min; Kyung Nam Kim; Se Jin Park; Seongtak Kim; Dongchul Suh; Donghwan Kim; Hae-Seok Lee; Yoonmook Kang. 2017. "Continuously deposited anti-reflection double layer of silicon nitride and silicon oxynitride for selective emitter solar cells by PECVD." Current Applied Physics 17, no. 4: 517-521.