Laser-induced sputtering of ZnO,TiO2, CdSe and GaP near threshold laser fluence

Sputtering of ZnO, TiO₂, CdSe and GaP induced by 10 ns laser pulses from a tunable dye laser has been investigated. It is shown that all of these materials exhibit the following characteristics: (1) non-linear dependence of sputtering yield on the excitation laser fluence, (2) existence of the threshold laser fluence, (3) dependence of the threshold laser fluence on laser wavelength, and (4) non-Maxwellian velocity distribution of sputtered particles. These results indicate that the laser-induced sputtering near threshold fluences is not a thermal effect but an effect of dense electron-hole plasma.