Background gas effects on structural properties in thin films deposited by pulsed laser deposition

Abstract

Pulsed laser deposition (PLD) in background gases is a promising method of preparing multicomponent functional thin films, because interactions between the ablated species and the background gases promote not only physical collisions but also chemical reactions, and affect the characteristics of the deposited films. The properties of indium oxide (In 2 O 3 ) thin films prepared by PLD in background gases were characterized in relation to the background gas pressures. Transparent crystalline In 2 O 3 thin films could be obtained at background gas pressures above 1.0 Torr on unheated glass substrates. This result can be accounted for by the background gas effects. The stoichiometric In 2 O 3 nuclei should be formed in the nonequilibrium high-pressure and high-temperature region generated by the shock front excited by the pulsed laser. Microstructures of the deposited thin films were also investigated using a cross-sectional transmission electron microscope. Initially, amorphous-like layers with a thickness of about 50 nm were formed on the substrates. Subsequently, strongly textured crystalline columns grew on the amorphous-like layers. We discuss the mechanism of thin film growth in PLD.