Stress Evolution during Growth of GaN (0001)/Al2O3 (0001) by Reactive DC Magnetron Sputter Epitaxy
2014 (English)In: Journal of Physics D: Applied Physics, ISSN 0022-3727, E-ISSN 1361-6463, Vol. 47, no 14, 145301- p.Article in journal (Refereed) Published
We study the real time stress evolution, by in-situ curvature measurements, during magnetron sputter epitaxy of GaN (0001) epilayers at different growth temperatures, directly on Al2O3 (0001) substrates. The epilayers are grown by sputtering from a liquid Ga target in a mixed N2/Ar discharge. For 600 °C, a tensile biaxial stress evolution is observed, while for 700 °C and 800 °C, compressive stress evolutions are observed. Structural characterization by crosssectional transmission electron microscopy, and atomic force microscopy revealed that films grew at 700 °C and 800 °C in a layer-by-layer mode while a growth temperature of 600 °C led to an island growth mode. High resolution Xray diffraction data showed that edge and screw threading dislocation densities decreased with increasing growth temperature with a total density of 5.5×1010 cm-2. The observed stress evolution and growth modes are explained by a high adatom mobility during magnetron sputter epitaxy at 700 - 800 °C. Also other possible reasons for the different stress evolutions are discussed.
Place, publisher, year, edition, pages
2014. Vol. 47, no 14, 145301- p.
GaN, Magnetron Sputter Epitaxy, Stress and Strain, Sputtering, XRD
Natural Sciences Condensed Matter Physics
IdentifiersURN: urn:nbn:se:liu:diva-84652DOI: 10.1088/0022-3727/47/14/145301ISI: 000333332600007ScopusID: 2-s2.0-84896955140OAI: oai:DiVA.org:liu-84652DiVA: diva2:560983