Investigation of interface and surface energy states in semiconductors by PA method D. M. Todorović, M. Smiljanić, V. Jović, M. Sarajlić and T. Grozdić Eur. Phys. J. Special Topics, 153 (2008) 247-250 Published online: 12 March 2008 DOI: 10.1140/epjst/e2008-00437-1