Calcium can be unintentionally incorporated during the growth of semiconductor devices. Using hybrid functional first-principles calculations, we assess the role of Ca impurities in GaN. Ca substituted on the cation site acts as a deep acceptor with a level ~1 eV above the GaN valence-band maximum. We find that for Ca concentrations of 1017 cm−3, the Shockley–Read–Hall recombination coefficient, A, of InGaN exceeds 106 s−1 for band gaps less than 2.5 eV. A values of this magnitude can lead to significant reductions in the efficiency of light-emitting diodes.
Shen J-X, Wickramaratne D, Dreyer CE, Alkauskas A, Young E, et al. (2017) Calcium as a nonradiative recombination center in InGaN. Applied Physics Express 10: 021001. Available: http://dx.doi.org/10.7567/apex.10.021001.
J.S., D.W., and C.V.d.W were supported by the U.S. Department of Energy (DOE), Office of Science, Basic Energy Sciences (BES) under Award No. DE-SC0010689. A.A. was supported by the Marie Sklodowska-Curie Action of the European Union (Project Nitride-SRH, Grant No. 657054). E.Y. and J.S.S. were supported by the KACST-KAUST-UCSB Solid State Lighting Program. Additional support was provided by the National Science Foundation IMI Program (Grant No. DMR08-43934). Computational resources were provided by the National Energy Research Scientific Computing Center, which is supported by the DOE Office of Science under Contract No. DE-AC02-05CH11231.