Thermal annealing effect on the structural properties of epitaxial growth of GaP on Si substrate

• Epitaxial growth of GaP/Si heterostructure.
• New method of thermal annealing is proposed.
• Effect of the thermal annealing on the grown films is studied.
• XRD and SEM characterizations confirm that this method is applicable.

The effect of post-growth annealing of epitaxial gallium phosphide grown on silicon substrates using gas-source molecular-beam epitaxy is described. The epitaxial layers were grown at substrate temperatures ranging from 250 to 550 °C. After optimizing the growth temperature, the prepared films were thermally annealed. Two thermal annealing methods are compared: annealing at a constant temperature and step-graded annealing, in which the temperature is raised by a constant rate per unit time. The effect of the thermal annealing on the crystal structure was studied by characterizing the epilayer using reflection high-energy electron diffraction (RHEED), X-ray diffraction (XRD) measurements, and scanning-electron microscopy (SEM). It was found that after thermal annealing, the epilayer exhibited a reconstructed RHEED pattern, and its quality was much improved.