Berlin 2015 – wissenschaftliches Programm
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HL: Fachverband Halbleiterphysik
HL 44: Quantum dots: Preparation and characterization
HL 44.8: Vortrag
Mittwoch, 18. März 2015, 11:30–11:45, EW 203
Growth of GaN quantum dots on AlN by MOVPE — •Konrad Bellmann1, Torsten Ernst1, Tim Wernicke1, Andre Strittmatter1,2, and Michael Kneissl1 — 1Technische Universität Berlin, Institute of Solid State Physics, Secretariat EW6-1, Hardenbergstrasse 36, 10623 Berlin, Germany — 2Otto-von-Guericke Universität Magdeburg, FNW/IEP/AHE, Universitätsplatz 2, 39106 Magdeburg
GaN quantum dots(QDs) embedded in an AlN matrix are very promising to achieve single photon sources at room temperature. This work will present a systematic study of GaN growth on an AlN layer by metal organic vapor phase epitaxy(MOVPE). Due to the 2.4 % lattice mismatch GaN growth on AlN is very sensitive to the surface energy during growth. A high V/III ratio >300 can shift the balance between surface energy and strain energy towards two dimensional growth. A low V/III ratio on the other hand shifts the balance towards Stranski Krastanow growth. We have investigated the GaN growth at 840 ∘C at different V/III ratios ranging between 70 and 1200 as well as different growth times from 0 s to 40 s. Independent of the V/III ratio GaN is first nucleating on the terrace until a uniform monolayer is formed. At high V/III ratio additional material gathers at the step edge leading to two dimensional growth with nonuniform edges. Growth at low V/III ratios results in three dimensional islands. The density increases during growth from 108 cm−2 to 1010 cm−2. Typical QDs exhibit heights of 1 - 4 nm and diameter of 20 - 50 nm. The growth results are summarized in a phase diagram based on the model by Daruka and Barabasi.