Mixed-anion GaAs1−ySby graded buffer heterogeneously integrated on Si by molecular beam epitaxy

Abstract

The growth, strain relaxation, and defect properties of a step-graded mixed-anion GaAs1−ySby buffer with a lattice misfit of >12% on a 6° off-cut (100) Si substrate grown by molecular beam epitaxy (MBE) have been investigated. This metamorphic graded buffer exhibited efficient strain relaxation and low threading dislocation densities of ≤107 cm−2 in the investigated range of misfits. High-resolution X-ray diffraction measurement demonstrated nearly ideal strain relaxation behavior with a surface rms roughness of ∼3.5 nm, which is attributed in part to dislocation glide. Thus, MBE-grown GaAs1−ySby anion-graded buffers are a promising “virtual substrate” technology for extending the performance and application of 6.1 Å device technology.