Regensburg 2019 – scientific programme
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HL: Fachverband Halbleiterphysik
HL 35: HL Poster II
HL 35.23: Poster
Wednesday, April 3, 2019, 17:30–20:00, Poster E
CVD growth of ZnO on sapphire with methane as reducing agent: Initial crystal formation process. — •Raphael Müller1, Florian Huber1, Okan Gelme1, Manfred Madel1, Alexander Minkow2, Ulrich Herr2, and Klaus Thonke1 — 1Institute of Quantum Matter / Semiconductor Physics Group, Ulm University — 2Institute for Functional Nanosystems, Ulm University
he initial crystal formation of zinc oxide (ZnO) layers in a high temperature chemical vapor deposition (CVD)-based growth process was investigated. In our process we use methane (CH4) to reduce ZnO powder. The resulting zinc vapor is locally re-oxidized at the spot of the substrate with pure oxygen, and thereby formes a ZnO layer. By controlling the gas flows one can control the II-VI ratio very precisely, as well as the duration of the growth. In the work presented, this scheme was used to grow a series of samples with increasing supply of zinc vapor in order to monitor the resulting layer formation. C-plane sapphire with aluminum nitride nucleation layer were used as substrates. To visualize and characterize the samples grown, atomic force microscopy, scanning electron microscopy and electron backscatter diffraction measurements were performed, as well as high resolution X-ray diffraction and photoluminescence measurements. We show that the ZnO heteroepitaxial layer is growing in c-direction right from the start of the process and forms a closed, smooth, high-quality single crystalline layer after a growth time of ten minutes only. The fundamental understanding of the layer formation is important for the ongoing studies of doping the ZnO layers with various donors.