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Stephan Six
Synthese epitaktischer AlN-Schichten mittels ionstrahlgestuetzter Laserablation
Betreuer: Prof. Dr. Bernd Rauschenbach [Experimentalphysik IV]
Datum der mündlichen Prüfung: 09.07.2001
102 Seiten, deutsch
Thin films of AlN were formed by ion assisted pulsed laser deposition process on single crystalline substrates. The films consist of the hexagonal wurtzitic AlN phase. On c-sapphire and r-sapphire substrates the films grow epitaxially. An argon or nitrogen ion bombardment during film growth leads to strongly strained films with a maximum c-axis expansion of 1.8 per cent at an argon ion energy of 500 eV. Due to the a-axis compression, which is correlated to the c-axis expansion, the lattice misfit to the c-sapphire substrate is reduced and therefore the expitaxial growth is found to be improved. The ion energy and growth temperature dependence of the observed lattice deformation is given by an simple model. It takes into account the annihilation of ion beam induced defects by their thermal activated diffusion to the film surface. A maximum of the argon ion beam induced defect concentration at an ion energy of 500 eV was predicted by the model in accordance with the maximum of the observed lattice deformation.