Theory of a carbon‐oxygen‐hydrogen recombination center in n‐type Si

We have recently found that in‐diffusion of hydrogen into n‐type Si crystals containing oxygen and carbon impurities can result in the formation of powerful recombination centers (M. Vaqueiro‐Contreras et al., to appear in PSS RRL). Here, we describe a combination of first‐principles calculations and electrical measurements to investigate the composition, structure, electrical activity and recombination mechanism of a carbon‐oxygen‐hydrogen complex (COH) in Si. We found a defect comprising a carbon‐oxygen complex connected to an H atom whose location depends on the charge state of the complex, and showing a calculated acceptor level at Ev + 0.3 eV, a few meV away from the observations. Bistable carbon–oxygen–hydrogen complex in silicon. Carbon, oxygen, hydrogen, and silicon atoms are shown in gray, red, black, and white, respectively.