Dr. Scarpulla develops theory linking excess carriers to point defects

Prof. Scarpulla and colleague Dr. Kirstin Alberi at NREL have developed the rigorous theory for calculating the concentrations of point defects in semiconductors and insulators when excess carries, such as those introduced by light or current, are present.  For nearly 100 years, theory has only been able to accommodate thermodynamic equilibrium in the dark.  However, whenever current flows or light or radiation strikes a semiconductor excess electrons and holes are present.  Since the quasichemical formation reactions for charged point defects like impurities, traps or dopants include electrons or holes as “reactants”, their concentration can influence the numbers of defects formed.  The theory suggests new ways to control defects during processing and fabrication of semiconductor devices, and also is tied into how devices change over time while in service.  The first article appeared in Scientific Reports (an open access journal) in May and further papers are forthcoming.