Size dependant core-level shifts have been investigated here for the InP nano-dots fabricated by the 3 keV ion irradiation. The self assembled nano dots exhibit core-level shifts and band gap expansion. The core-level shifts are however inhomogeneous, not exhibiting any systematic dependence on the size of the dots. The inhomogeneous core-level shifts as well as the band gap expansion are the result of cumulative effect of the nano-dimensional sizes and the stoichiometric variations in InP nano dots. The nucleation of the self assembled nano dots is promoted by the creation of In-rich zones after the preferential sputtering of P. Decreased In/P concentration, at longer sputtering durations, leads to the fragmentation of dots. © 2009 Elsevier Ltd. All rights reserved.