Temperature effect study on structural and morphological properties of In .08Ga .92As/GaAs structures grown by MOVPE

Abstract

In .08Ga .92As layers were grown on the GaAs(0 0 1) substrate by atmospheric pressure metalorganic vapour-phase epitaxy (AP-MOVPE). Among growth conditions, only growth temperature was varied in the range 520–680 °C. This temperature interval keeps solid indium composition constant when fixing vapour indium composition. In order to improve crystal quality and to contribute to the understanding of the growth kinetic, we have studied the temperature effect on morphological and structural properties and growth process of In .08Ga .92As/GaAs structures. Surface morphology evolution of InGaAs films (RMS surface roughness, hatchings and islands of formations, densities, sizes and uniformities, etc.) and growth process (growth anisotropy, etc.) versus growth temperature were investigated by atomic force microscopy (AFM) and plan-view scanning electronic microscopy (SEM). Dislocations density and alloys disorder (by using Urbach energy) changes of InGaAs alloys were examined by high-resolution X-ray diffraction (HRXRD) in rocking curves mode and optical absorption (OA) measurements, respectively. A correlation between results and comparison with the literature has been given. All measurements show that optimal growth temperature regarding crystal quality (defects density, alloys disorder, etc.) is about 520 °C. Besides, surface morphology of In .08Ga .92As at this temperature was specified by the presence of hatchings and the absence of islands. As a manufactured diffraction grating, we find that hatchings network can diffract a 632.8 nm incident laser.