Crystalline quality of ZnSe thin films grown on GaAs by pulsed laser deposition in He and Ar ambients

Epitaxial films of ZnSe with a thickness of approximately 1 mum, were deposited on (001) semi-insulating GaAs by pulsed laser deposition using a third harmonic Nd-YAG laser at 10(-6) torr vacuum and at various pressures of He and Ar gases. The best crystalline quality of the ZnSe epilayer was obtained when the deposition was carried out at 10(-4) torr of He. The full width at half maximum of the X-ray diffraction rocking curve of the ZnSe film deposited at 400 degreesC in 10(-4) torr of He was approximately 230 arcsecs, A comparison of the reciprocal lattice space mappings showed that ZnSe epilayers deposited in Ar ambient have a much larger variation of lattice spacing and strain than those grown in vacuum and He ambient. The scanning electron micrographs showed that the epilayers of ZnSe deposited at 10(-4) torr of He have the least particulate density. Possible reasons for the observed improvement in the crystalline quality are discussed. (C) 2001 Elsevier Science B.V. All rights reserved.