Structure and morphology of GaInAsP solid solutions on GaAs substrates grown by pulsed laser deposition

Abstract

GaInAsP solid solutions are synthesized on GaAs substrates by pulsed laser deposition and the effect of the laser fluence on the morphology and structure of the films is studied. It is found that the surface of the films is textured with In microdroplets. It is established that an increase in the laser fluence from 2.0 to 3.2 J/cm2 increases the average size of the In microdroplets from 0.4 to 1.4 µm, decreases their density from 0.22 to 0.02 µm−2 and also increases the root-mean-square surface roughness of the GaInAsP films from 0.24 to 0.34 nm. The GaInAsP films contain structural defects in the form of misfit dislocations. X-ray diffraction and atomic force microscopy show that the film growth occurs in two stages, with island growth transforming into a quasi-layer-by-layer growth mode. The structural properties and phase composition of the target and GaInAsP films are studied. X-ray diffraction and Raman spectroscopy results indicate the inhomogeneity of the phase composition and the predominance of the short-range order of chemical bonds in the synthesized GaInAsP solid solutions on the GaAs substrates.