engleski

GaAs Thin Films Deposited by Colliding Laser Produced Plasma

Pulsed laser deposition (PLD) is a standard technique to fabricate thin films of various materials. To obtain the best quality of the film, laser produced plasma must be spatially homogeneous in density and temperature and preserve steichiometry of the target. Colliding laser produced plasmas are formed when two closely produced seed plasmas collide. In collisional front between such two counter- propagating plasmas a stagnation layer may be formed which lasts longer and is of better quality for thin film deposition than seed plasmas. Stagnation layer, instead of seed plasma (regular PLD), is thus interesting media for deposition of thin films. In this work we present the results of thin film of GaAs deposition in vacuum (p=10^-4 mbar) by colliding laser plasmas produced on a planar target. Seed plasmas were separated by various distances (from 1.7 up to 3 mm). Distance between target and substrate was varied form 2 to 5 cm. Both substrate and target were on floating potential and room temperature. Results of a difference between standard PLD and deposition by stagnation layer, or colliding plasma deposition, are shown. Thin films were characterized by XRD, AFM and SEM in terms of film thickness, roughness, content, steichiometry, etc. and by film transmittance using spectrophotometry. Colliding laser produced plasmas were monitored during deposition by time and spatial resolved optical emission spectroscopy and by cavity ring-down spectroscopy.

sudarne laserski proizvedene plazme

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