Ertekin, ElifWinkler, Mark T.Recht, DanielSaid, Aurore J.Aziz, MichaelBuonassisi, TonioGrossman, Jeffrey C.2016-06-302012Ertekin, Elif, Mark T. Winkler, Daniel Recht, Aurore J. Said, Michael J. Aziz, Tonio Buonassisi, and Jeffrey C. Grossman. 2012. “Insulator-to-Metal Transition in Selenium-Hyperdoped Silicon: Observation and Origin.” Physical Review Letters 108, no. 2. doi:10.1103/physrevlett.108.026401.0031-9007http://nrs.harvard.edu/urn-3:HUL.InstRepos:27417437Hyperdoping has emerged as a promising method for designing semiconductors with unique optical and electronic properties, although such properties currently lack a clear microscopic explanation. Combining computational and experimental evidence, we probe the origin of sub–band-gap optical absorption and metallicity in Se-hyperdoped Si. We show that sub–band-gap absorption arises from direct defect– to–conduction-band transitions rather than free carrier absorption. Density functional theory predicts the Se-induced insulator-to-metal transition arises from merging of defect and conduction bands, at a concentration in excellent agreement with experiment. Quantum Monte Carlo calculations confirm the critical concentration, demonstrate that correlation is important to describing the transition accurately, and suggest that it is a classic impurity-driven Mott transition.en-USJournal Article2016-06-3010.1103/PhysRevLett.108.026401