Growth of ZnO(0001) on GaN(0001)/4H-SiC buffer layers by plasma-assisted hybrid molecular beam epitaxy

• Published in: Journal of crystal growth Vol. 426; pp. 129 - 134
• Main Authors: Adolph, David, Tingberg, Tobias, Ive, Tommy
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 15.09.2015
• Subjects: A2. Single crystal growth; A3. Molecular beam epitaxy; B1. Gallium nitride; B1. Nitrides; B1. Oxides; B1. Zinc oxide; Buffer layers; Crystal growth; Deposition; Electron mobility; Gallium nitride; Gallium nitrides; Molecular beam epitaxy; Nitrides; Oxides; Single crystal growth; Zinc oxide; B1. Oxides; A3. Molecular beam epitaxy; B1. Nitrides; A2. Single crystal growth; B1. Gallium nitride; B1. Zinc oxide
• ISSN: 0022-0248; 1873-5002
• DOI: 10.1016/j.jcrysgro.2015.05.026

Plasma-assisted molecular beam epitaxy was used to grow ZnO(0001) layers on GaN(0001)/4H-SiC buffer layers deposited in the same growth chamber equipped with both N- and O-plasma sources. The GaN buffer layers were grown immediately before initiating the growth of ZnO. Using a substrate temperature of 445°C and an O2 flow rate of 2.5 standard cubic centimeters per minute, we obtained ZnO layers with statistically smooth surfaces having a root-mean-square roughness of 0.3nm and a peak-to-valley distance of 3nm as revealed by atomic force microscopy. The full-width-at-half-maximum for x-ray rocking curves obtained across the ZnO(0002) and ZnO(10 1¯ 5) reflections was 198 and 948arcsec, respectively. These values indicated that the mosaicity of the ZnO layer was comparable to the corresponding values of the underlying GaN buffer layer. Reciprocal space maps showed that the in-plane relaxation of the GaN and ZnO layers was 82% and 73%, respectively, and that the relaxation occurred abruptly during the growth. Room-temperature Hall-effect measurements revealed that the layers were inherently n-type and had an electron concentration of 1×1019cm−3 and a Hall mobility of 51cm2/Vs. •PAMBE growth of ZnO(0001) on GaN(0001)/4H-SiC layers with the same growth chamber.•The ZnO-layers were immediately grown on the in-situ grown GaN never exposed to air.•ZnO layers with a RMS of 0.3 nm and a PV of 3 nm was achieved with a high O/Zn-ratio.•The FWHM XRCs for the ZnO(0002) and ZnO(10-15) reflections was 198 and 948 arcsec.•The n-type ZnO layers had an n=1×1019cm−3, a μ=51cm2/Vs and an Rs of 1123Ω/□.