Photoemission study of the band bending and chemistry of sodium sulfide on GaAs (100) - Spindt, C. J.; Besser, R. S.; Cao, R.; Miyano, K.; Helms, C. R.; Spicer, W. E. (American Institute of Physics (AIP), 1989)
http://dx.doi.org/10.1063/1.100744
Keywords: U