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

• Published in: Journal of crystal growth 2013-01, Vol.363, p.44-48
• Main Authors: Ji, Lian, Lu, S.L., Zhao, Y.M., Tan, M., Dong, J.R., Yang, H.
• Format: Article
• Language: English
• Subjects: A3. Organometallic vapor phase epitaxy; B1. Gallium compounds; B2. Semiconducting gallium compounds; B2. Semiconducting indium compounds; B3. Solar cells; Buffer layers; Buffers (chemistry); Chemical vapor deposition; Chemical vapor deposition (including plasma-enhanced cvd, mocvd, etc.); Condensed matter: structure, mechanical and thermal properties; Cross-disciplinary physics: materials science; rheology; Defects and impurities: doping, implantation, distribution, concentration, etc; Density; Devices; Exact sciences and technology; Indium phosphides; Materials science; Methods of deposition of films and coatings; film growth and epitaxy; Morphology; Physics; Surfaces and interfaces; thin films and whiskers (structure and nonelectronic properties); Theory and models of film growth; Thin film structure and morphology; Transmission electron microscopy
• ISSN: 0022-0248; 1873-5002
• DOI: 10.1016/j.jcrysgro.2012.09.035

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 2.74nm was obtained. Transmission Electron Microscopy (TEM) measurement revealed a threading dislocation density on the order of or below ∼106cm−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 2.74nm was obtained. ► Threading dislocation density is on the order of or below ∼106cm−2.