Design And Performance Of Optical Detectors Fabrication Setup Using Pulsed Laser Deposition (PLD)

PLD system was used in the preparation of nano structured thin layers to be used as optical detectors. Our home made on—axis PLD setup utilizes XeCl excimer laser (308 nm, Pulse duration of 7 ns, repetition rate of 200 Hz). The laser energy is kept at 8 mj, and the vacuum chamber has been pumped to a background pressure of 10^-5 mbar. The films can be grown at different substrate temperatures in the range of 25-400° C. The substrate temperature was always kept below 400° C by using advanced temperature control system. The target-to-substrate distance was variable from 2 to 6 cm. SiO₂ was used as substrates because of its low refractive index and high transparency in the UV, visible and near infrared ranges of spectra. LIPS technique has been used for plasma diagnoses during film deposition, using a double monochromator provided with photon detector. Homogenous thin films in the order of 20-200 nm thickness were obtained. Moreover, both amorphous and crystalline thin films can be obtained by adjusting the substrate temperature, target—substrate distance, type of substrate and finally pressure of ambient gas.