Compositionally undulating step-graded InAsyP1−y buffer layer growth by metal-organic chemical vapor deposition

Compositionally undulating step-graded InAsyP1−y buffer layers were grown by metal-organic chemical vapor deposition (MOCVD) to relax the strain of In0.68Ga0.32As with InP substrate. The strain relaxation and surface morphology are strongly dependent on the thickness of each step-graded buffer layer. With an optimized buffer thickness design, a 3-μm-thick In0.68Ga0.32As epilayer shows a high crystal quality with no measurable tetragonal distortion and a very low surface roughness of 2.74 nm was obtained. Transmission Electron Microscopy (TEM) measurement revealed a threading dislocation density on the order of or below ∼106 cm−2. Our results indicate that the compositionally undulating step-graded InAsyP1−y buffers grown on InP are very promising to be virtual substrates of infrared and high speed metamorphic devices.

► Compositionally undulating step-graded InAsyP1−y buffer layers were grown to relax the strain of In0.68Ga0.32As with InP substrate.
► The thickness of InAsyP1−y buffer layers has a great influence on In0.68Ga0.32As crystal quality and surface morphology.
► A very low surface roughness of 2.74 nm was obtained.
► Threading dislocation density is on the order of or below ∼106 cm−2.