The InP nanostructures have been fabricated by low-energy Ar+-ion of dose 1 × 1018 cm-2 and energy 50 keV, at normal incidence. The InP nanodot size varies from 50 to 90 nm. Photoluminescence spectra show blue shifted visible emission band at 1.98 eV, and quenching of the band edge emission from the nanopatterned surface. The blue-shifted emission band arises due to size convoluted band-to-band emission form the surface nanodots while the defects formation in the irradiated surface leads to the quenching of band edge emission. Thermal annealing results in clustering of the patterned surface and enhancement of the band edge emission accompanied with absence of visible band. Our results show that the origin of visible emission is from the surface nanodots and not from the nanocrystallites in the implanted surface region. This is corroborated by the wavelength dependence of photoluminescence measurement by probing different depth of the disordered region.