Study optical properties for pbS thin films before and after irradiation by CO2 laser

Abstract

AbstractIn this study, Lead sulphide (PbS) thin films were deposited on glass substrates using the thermal vacuumevaporation technique at lressure 105 torr. The prepared films were arulealed to 200'C by using oven undervacuum with pressure I 0 ' torr then the samples inadiated by CO2 laser of power ( I wan) and wavelength ( 10.6)pm at distance (10 cm) from the source for (5 sec). The optical characteristics ofthe prepared thin films havebeen investigated using IR spectrophotometer. Optical constants such as absorption, reflection, absorptioncoefficient (o), Band gap energy (EJ, extinction coefficient (K), rellactive index (n), and complex dielectricconstants (t.&s,) were evaluated from Eansmission specha. The results show that the laser irradiation causedecreasing in tansmittance, reflection, band gap energy, refractive index and in the real part of dielectricconstant while increasing in the absorption, extinction co€fficient and imaginary pan ofdielectric constant, inthe investigated region