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Chinese
2020年6月27-29日
上海新国际博览中心

P.S.Raghavan

P.S.Raghavan
CTO, GT Advanced Technologies
首席技术官

个人简介 / Biography

Dr. P.S. Raghavan is GT Advanced Technologies' Chief Technology Officer. Dr. Raghavan brings over 33 years of industrial and academic experience in crystal growth instrumentation, crystal growth of semiconducting (Silicon, Silicon carbide, III-V and II-VI) materials, Oxides (Al203, LiNbO3), NLO materials, scintillation detecting materials and advanced electronic and photonic devices. His decades of experience in developing technology and capital equipment has resulted in the successful commercialization of industry leading silicon, sapphire, silicon carbide and Gallium Nitride crystal growth furnaces for the solar, LED, and consumer and power electronics manufacturing industries.

Prior to joining GT in 2002, he was involved in crystal growth research and held positions as Visiting Professor, Department of Electrical Engineering, NTHU, Hsinchu, Taiwan, Assistant Professor, Crystal Growth Centre, Anna University, and Reader and Head Instrumentation, Alagappa University, India.

Dr. Raghavan holds a master's degree in physics, a master of philosophy degree in physics and a Ph.D. in crystal growth of III-V compounds. He worked as postdoctoral fellow at internationally acclaimed laboratories worldwide and has 60 research publications in international journals, 8 patents and 100 publications in national/International conferences. He has co-authored 3 books on crystal growth and has earned several international awards for his contribution to the field of crystal growth technology.

摘要 / Abstract

The growing demand for power electronic devices for automotive, photovoltaic, transportation, motor drives and solid state transformers creates an enormous demand for wide band gap semiconducting materials. Two of the popular wide bandgap materials are silicon carbide (SiC) and gallium nitride (GaN). While GaN - based devices can be used for low voltages, SiC is the workhorse for voltages >600. Progress in the availability of larger diameter SiC wafers has driven the final cost of SiC power electronic devices closer to Si IGBT‘s. Today, SiC wafers are approximately 10x more expensive than silicon wafers, but even with higher SiC substrate cost, SiC based solutions provide considerable cost savings at the system level due to the small chip size, reduced passive components, and higher conversion efficiency.

As such, SiC substrates contribute 50% of the cost of the whole device value chain. While elemental semiconductor materials such as silicon can be grown as a totally defect-free crystal, SiC cannot be grown defect free due to fundamental issues that include vapor phase growth, multiple polytypes, and spiral growth mechanism.

The higher substrate cost for SiC results from the crystal growth process and the yield at different stages of the process. SiC is grown from a gas or liquid phase process that involves the following: (a) the generation of reactants (sublimation or non-congruent melt); (b) the transport of reactants to the growth surface (required temperature gradients); (c) adsorption at the growth surface (supersaturation); (d) nucleation; and (e) finally crystal growth – advancement of gas solid interface or solid liquid interface. Leveraging its deep expertise in crystal growth, GT Advanced Technologies has been involved in the development of commercial scale silicon carbide crystal growth equipment since the early 2000’s to address the growing needs of the power electronics industry. The Company’s extensive thermal modeling experience combined with equipment design has enabled unique production processes resulting in high quality boules with low crystalline defects and commercial run-to-run reproducibility.

GT has an aggressive roadmap to cut the substrate cost in half in next few years. A detailed comparison of technology readiness of various SiC crystal growth techniques, along with defect reduction, correlation of defects to devices and cost modelling of low cost SiC wafers will be presented in the talk.