"Understanding Point Defects in Semiconductors using First Principles Simulations" 

Yi Yang, MSE PhD Candidate 

Advisor: Professor Arun Kumar Mannodi Kanakkithodi

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ABSTRACT

Semiconductors, covering a broad spectrum from elemental silicon and compound III-Vs to complicated oxides and perovskites, have garnered extensive attention for their versatile applications in photovoltaics, electronics, light emission, and catalysis. Their bandgaps and electronic structures can be modulated via doping or alloying, enable efficient charge transport and optical responses, driving their adoption as cost-effective alternatives to traditional materials. Composed largely of abundant elements, semiconductors offer remarkable property engineering via composition and defect control, fueling advancements in renewable energy and optoelectronics. Despite decades of investigation, persistent challenges include defect-induced carrier recombination, limited dopability, and stability issues under operational conditions still exist. In recent years, first-principles simulations have emerged as a powerful tool to address these limitations by providing atomic-level insights into defect behavior.

This review delves into density functional theory (DFT) frameworks for defect modeling, detailing formation energy calculations, charge corrections, supercell considerations, and functional influences, alongside post-processing for Fermi levels, carrier densities, and dopability tuning. Through case studies on ion migration in perovskites and oxides, we highlight DFT's unique capabilities of high-throughput prediction and revealing mechanism for guiding future semiconductor design.