Morphological and chemical evolution on InP(1 0 0) surface irradiated with femtosecond laser

Single crystalline InP was ablated in air with p-polarized Ti:sapphire femtosecond laser at a fixed laser fluence of 82 mJ/cm2. Ripples parallel to the laser polarization direction were found by scanning electron microscopy and atomic force microscopy to form for laser pulses ranging from 50 to 1000, whereas flower-like structures appeared for laser pulses of 104 and above. Analysis by X-ray photoelectron spectroscopy showed formation of indium and phosphorus oxides on the irradiated surface and the amounts of oxides increased with increasing number of laser pulses. The oxide formation is attributed to chemical reaction between the ultrafast laser ablation plume and oxygen in air, and formation of the flower-like structures is shown to be related to deposition of the oxides on the irradiated surface.