Study of stable p-type conductivity in bismuth-doped ZnO films grown by pulsed-laser depositionJ. W. Lee, N. G. Subramaniam, J. C. Lee, S. Kumar S and T. W. KangEPL, 95 4 (2011) 47002DOI: https://doi.org/10.1209/0295-5075/95/47002