Plasma dynamics studies during deposition of thin film PbTe on a glass substrate

PbTe thin films were prepared by pulsed laser deposition using a Nd:YAG laser (532 nm) in an argon atmosphere. Dynamic processes in the gas phase induced by Nd:YAG laser ablation of PbTe are investigated by analyzing the light emitted by the plume. Pressure in the chamber varied from 1.0×10^-5 to 1.0 mbar. Space and time-resolved optical spectroscopy measurements indicate the presence of both neutral, Pb(I) and Te(I) and ionized, Pb(II) and Te(II), species. The velocities of the species remain unchanged for argon pressures up to 10^-1 mbar, which suggests that expansion of the plume occurs without further collision with the foreign gas in this pressure range. It is found that an addition of 5×10^-1 mbar Ar enhances the emission line intensity and leads to a decrease in species velocity observed at large distances from the target surface. Furthermore, a region of maximum emission intensity at distance of 5-10 mm from the target is found when a gas environment is present.