Growth mode transition and relaxation of thin InGaN layers on GaN (0001)

• Published in: Journal of crystal growth 2013-06, Vol.372, p.65-72
• Main Authors: Pristovsek, Markus, Kadir, Abdul, Meissner, Christian, Schwaner, Tilman, Leyer, Martin, Stellmach, Joachim, Kneissl, Michael, Ivaldi, Francesco, Kret, Sławomir
• Format: Article
• Language: English
• Subjects: A1. Morphological stability; A1. Stresses; A1. Surface processes; A3. Metalorganic vapour phase epitaxy; B1. Nitrides; B2. Semiconducting III–V materials; Cross-disciplinary physics: materials science; rheology; Crystal growth; Density; Deposition; Exact sciences and technology; Gallium nitrides; Indium; Indium gallium nitrides; Materials science; Mathematical analysis; Methods of crystal growth; physics of crystal growth; Methods of deposition of films and coatings; film growth and epitaxy; Nanoscale materials and structures: fabrication and characterization; Other topics in nanoscale materials and structures; Physics; Quantum dots; Theory and models of crystal growth; physics of crystal growth, crystal morphology and orientation; Thin films; Vapor phase epitaxy; growth from vapor phase
• ISSN: 0022-0248; 1873-5002
• DOI: 10.1016/j.jcrysgro.2013.03.012

We have investigated on the growth of InGaN layers and quantum dots (QDs) on GaN (0001) by metal-organic vapour phase epitaxy. For indium contents above 15% strained QDs form after a certain layer thickness (Stranski Krastanov mode) with typical heights of 2–3nm. The QD density increases fast during further deposition until saturation above 1010cm−2. Growing thicker layers results in larger but relaxed structures and leave only a small growth window for strained QDs. The data indicate that QDs form when the accumulated strain energy calculated from indium content and layer thickness exceeds a critical value which is independent from the indium content. The same behaviour was found for the critical thickness of relaxation, indicating that relaxation occurs via the relaxation of large QDs with heights above 3nm. •First systematic measurement of the wetting layer thickness for InGaN in MOVPE.•Confirmed that the density of QDs depends on amount of InGaN deposited.•Simple model based on using constant energy describes QD formation as well as relaxation.