Heteroepitaxial growth of InGaP on Si with InGaP/GaP step-graded buffer layers

Heteroepitaxial growth of indium gallium phosphide (In 1- x Ga x P) with x ∼0.7 was successfully achieved on a silicon (Si) substrate by introducing step-graded buffer layers which consist of a gallium phosphide (GaP) buffer layer and In 1- x Ga x P layers whose gallium (Ga) composition x decreases in steps toward the direction of the growth. For the GaP buffer layer, the effects of thermal cycle annealing (TCA) were studied using a Rutherford back scattering channeling (RBS-C) measurement. The layer was shown to be improved greatly and a high-quality heteroepitaxial GaP layer could be obtained in the region close to the surface by introducing TCA. For the In 1- x Ga x P step-graded layers, the lattice strain, investigated using X-ray diffraction, was shown to be more relaxed using a Si substrate than using a GaP substrate. The growth of InGaP on a Si substrate with the step-graded layers is an effective method to reduce the strain in the InGaP layer.