GaN films grown on (0 0 1) and (1 1 0) MgF2 substrates by plasma-assisted molecular beam epitaxy (PA-MBE)

• Published in: Journal of crystal growth Vol. 531; p. 125303
• Main Authors: Meyer, Kevin, Barnstedt, Juergen, Conti, Lauro, Hanke, Lars, Kalkuhl, Christoph, Kappelmann, Norbert, Rauch, Thomas, Stelzer, Beate, Werner, Klaus, Schaadt, Daniel M.
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 01.02.2020; Elsevier BV
• Subjects: A3. Molecular beam epitaxy; B1. magnesium fluoride; B1. Nitrides; B2. Semiconducting gallium compounds; B3. UV detector; Crystallography; Epitaxial growth; Gallium nitrides; Grain size; Hexagonal phase; Inclusions; Magnesium fluorides; Molecular beam epitaxy; Space applications; Substrates; Wetting; A3. Molecular beam epitaxy; B1. Nitrides; B2. Semiconducting gallium compounds; B1. magnesium fluoride; B3. UV detector
• ISSN: 0022-0248; 1873-5002
• DOI: 10.1016/j.jcrysgro.2019.125303

•Growth of cubic GaN on MgF2 by plasma assisted molecular beam epitaxy.•Possible on both tested orientations, (0 0 1) and (1 1 0), of MgF2.•Better layer quality by prior wetting of the surface with GaN. The growth of gallium nitride (GaN) on magnesium fluoride (MgF2) by plasma-assisted molecular beam epitaxy (PA-MBE) was investigated under different conditions. GaN films on MgF2 substrates are a promising material combination for UV-detectors in space applications. Two different crystallographic orientations of MgF2 were used to analyse the influence on the formation of GaN. The GaN layers on (0 0 1) MgF2 had better quality in comparison to a (1 1 0) surface orientation. Under a high Ga flow only cubic β-GaN without hexagonal α-GaN was formed at the growth on (0 0 1) MgF2. The layers, grown under other conditions, consisted mainly of the meta-stable cubic GaN with inclusions of the hexagonal phase. With higher substrate temperatures a rougher surface and a higher grain size could be observed. The best results were obtained with a substrate temperature of 450 °C and a prior wetting of the surface with only gallium. In this case the relative low substrate temperature could be compensated. In X-ray diffraction (XRD) analysis mainly (1 1 1), (2 2 2) and (2 2 0) peaks were observed indicating that mostly cubic GaN was present.