Dr . Saravanan Somasundaram | Indian Institute of Technology Bombay (original) (raw)
I am Saravanan, my passion is research. I did my Ph.D. from Cochin University of Science and Technology and my area of research is organic semiconductors. After my Ph.D. I spent almost 3 years as Post-doctoral Research fellow in the Indian Institute of Science and in the University of New South Whales @ Australian Defense Force Academy. I was working for TATA BP Solar India ltd as a Deputy Manager - Technology almost 5 years and quit in thirst of exploring the innovative processes in crystalline silicon solar cells.
Currently I am in National Centre for Photovoltaic Research and Education, Indian Institute of Technology, Bombay. I am the system in charge of crystalline silicon solar cell fabrication and characterisation lab. We, the crystalline silicon solar cell group working towards the low cost high efficiency solar cells with advanced technologies.
Supervisors: Prof Vikram Jayaram and Prof M R Anantharaman
Phone: +919611222788
Address: Senior Project Manager - Technical,
Silicon Solar Cell Process & Technology,
National Centre for Photovoltaic Research and Education,
Indian Institute of Technology, Bombay
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Papers by Dr . Saravanan Somasundaram
Silicon nitride (SiNx:H) film is a promising material for antireflection coatings and for surface... more Silicon nitride (SiNx:H) film is a promising material for antireflection coatings and for surface passivation in the conventional crystalline silicon (c-Si) solar cell process. In this work, SiNx:H antireflective coating films were successfully fabricated by using conventional batch-type plasma-enhanced chemical vapour deposition system. Film thickness and refractive index (RI) of the samples were evaluated as functions of growth parameters, such as growth pressure, total gas flow rate, radio frequency power and NH3 to SiH4 gas ratio. In this work, an attempt has been made to elucidate the variation of electrical parameters of the multicrystalline silicon solar cells with respect to the gas flow rates and RI. The gas flow rate ratio, , was varied in the range of 0.09 to 0.12 by maintaining the total flow rate of the process gases at 7600 sccm. The variation of RI from 2.03 to 2.18 and the electrical parameters of the solar cells with respect to the gas flow ratio were interpreted and incorporated. Also the variation of efficiency correlated with the flow rate of SiH4 during the deposition of silicon nitride process.
Silicon-based photovoltaics (PV) plays the dominant role in the history of PV due to the continuo... more Silicon-based photovoltaics (PV) plays the dominant role in the history of PV due to the continuous process and technology improvement in silicon solar cells and its manufacturing flow. In general, silicon solar cell process uses either p-type- or n-type-doped silicon as the starting material. Currently, most of the PV industries use p-type, boron-doped silicon wafer as the starting material. In this work too, the boron-doped wafers were considered as the starting material to create pn junction and phosphorus was used as n-type doping material. Industries use either phosphorous oxy chloride (POCl3) or ortho phosphoric acid (H3PO4) as the precursor for doping phosphorous. While the industries use POCl3 as the precursor, the throughput is lesser than that of the industries’ use of H3PO4 due to the manufacturing limitations of the POCl3-based equipments. Hence, in order to achieve the operational excellence in POCl3-based equipments, business strategies such as the Six Sigma methodology have to be adapted. This paper describes the application of Six Sigma Define–Measure–Analyze–Improve–Control methodology for throughput improvement of the phosphorus doping process. The optimised recipe has been implemented in the production and it is running successfully. As a result of this project, an effective gain of 0.9 MW was reported per annum.
Crystalline silicon solar cell technology continues to be dominant in the photovoltaic (PV) techn... more Crystalline silicon solar cell technology continues to be dominant in the photovoltaic (PV) technology due to its novel process flow and the clear understanding of the material. Being a mature material-based technology; on the one hand, it has quite a few opportunities for improvement, on the other hand, the expansion of solar energy should depend on this technology. Due to increase in the global energy consumption and high competition level in the market, it has become necessary to show significant improvement in the performance of the present process/product. The demand for high efficiency solar cells at low costs with shorter cycle times forced the manufacturing industries to improve their processes by applying systematic methodologies such as Six Sigma. This paper illustrates the importance of anti-reflective coatings (ARCs) on the silicon solar cell processes and the successful implementation of Six Sigma to improve the efficiency of the silicon solar cells. The different phases of the Six Sigma DMAIC approach applied to the process and the results are interpreted.
Minority carrier lifetime plays a significant role in the performance of silicon (Si) solar cells... more Minority carrier lifetime plays a significant role in the performance of silicon (Si) solar cells, due to its importance in qualifying the bare silicon wafers. In order to fabricate the high efficiency industrial Si solar cells, high life time based silicon wafers are a prerequisite which strongly depends on the defects and trap concentrations of the wafer. In the present work, a systematic study of the variation in the minority effective carrier lifetime on Si solar cells has been studied. The solar grade mono silicon wafers used for this study had bulk carrier life time <; 10 μ secs with bulk resistivity of 0.5-3 Ω cm. The silicon solar cells were fabricated in the production line by employing the conventional silicon solar cell process. As expected it has been observed that a change of effective life time in bare wafers improved the cell performance. This paper narrates the electrical performance of the mono crystalline silicon solar cells with respect to the different effective carrier life time of the bare wafers. The results are compared and correlated with the passivation process and have been explained with respect to the different effective carrier life time.
Silicon nitride (SiNx:H) film is a promising material for antireflection coatings and for surface... more Silicon nitride (SiNx:H) film is a promising material for antireflection coatings and for surface passivation in the conventional crystalline silicon (c-Si) solar cell process. In this work, SiNx:H antireflective coating films were successfully fabricated by using conventional batch-type plasma-enhanced chemical vapour deposition system. Film thickness and refractive index (RI) of the samples were evaluated as functions of growth parameters, such as growth pressure, total gas flow rate, radio frequency power and NH3 to SiH4 gas ratio. In this work, an attempt has been made to elucidate the variation of electrical parameters of the multicrystalline silicon solar cells with respect to the gas flow rates and RI. The gas flow rate ratio, , was varied in the range of 0.09 to 0.12 by maintaining the total flow rate of the process gases at 7600 sccm. The variation of RI from 2.03 to 2.18 and the electrical parameters of the solar cells with respect to the gas flow ratio were interpreted and incorporated. Also the variation of efficiency correlated with the flow rate of SiH4 during the deposition of silicon nitride process.
Silicon-based photovoltaics (PV) plays the dominant role in the history of PV due to the continuo... more Silicon-based photovoltaics (PV) plays the dominant role in the history of PV due to the continuous process and technology improvement in silicon solar cells and its manufacturing flow. In general, silicon solar cell process uses either p-type- or n-type-doped silicon as the starting material. Currently, most of the PV industries use p-type, boron-doped silicon wafer as the starting material. In this work too, the boron-doped wafers were considered as the starting material to create pn junction and phosphorus was used as n-type doping material. Industries use either phosphorous oxy chloride (POCl3) or ortho phosphoric acid (H3PO4) as the precursor for doping phosphorous. While the industries use POCl3 as the precursor, the throughput is lesser than that of the industries’ use of H3PO4 due to the manufacturing limitations of the POCl3-based equipments. Hence, in order to achieve the operational excellence in POCl3-based equipments, business strategies such as the Six Sigma methodology have to be adapted. This paper describes the application of Six Sigma Define–Measure–Analyze–Improve–Control methodology for throughput improvement of the phosphorus doping process. The optimised recipe has been implemented in the production and it is running successfully. As a result of this project, an effective gain of 0.9 MW was reported per annum.
Crystalline silicon solar cell technology continues to be dominant in the photovoltaic (PV) techn... more Crystalline silicon solar cell technology continues to be dominant in the photovoltaic (PV) technology due to its novel process flow and the clear understanding of the material. Being a mature material-based technology; on the one hand, it has quite a few opportunities for improvement, on the other hand, the expansion of solar energy should depend on this technology. Due to increase in the global energy consumption and high competition level in the market, it has become necessary to show significant improvement in the performance of the present process/product. The demand for high efficiency solar cells at low costs with shorter cycle times forced the manufacturing industries to improve their processes by applying systematic methodologies such as Six Sigma. This paper illustrates the importance of anti-reflective coatings (ARCs) on the silicon solar cell processes and the successful implementation of Six Sigma to improve the efficiency of the silicon solar cells. The different phases of the Six Sigma DMAIC approach applied to the process and the results are interpreted.
Minority carrier lifetime plays a significant role in the performance of silicon (Si) solar cells... more Minority carrier lifetime plays a significant role in the performance of silicon (Si) solar cells, due to its importance in qualifying the bare silicon wafers. In order to fabricate the high efficiency industrial Si solar cells, high life time based silicon wafers are a prerequisite which strongly depends on the defects and trap concentrations of the wafer. In the present work, a systematic study of the variation in the minority effective carrier lifetime on Si solar cells has been studied. The solar grade mono silicon wafers used for this study had bulk carrier life time <; 10 μ secs with bulk resistivity of 0.5-3 Ω cm. The silicon solar cells were fabricated in the production line by employing the conventional silicon solar cell process. As expected it has been observed that a change of effective life time in bare wafers improved the cell performance. This paper narrates the electrical performance of the mono crystalline silicon solar cells with respect to the different effective carrier life time of the bare wafers. The results are compared and correlated with the passivation process and have been explained with respect to the different effective carrier life time.
Manufacturing the Solar Future: The 2013 Production Annual, 2013
