Dresden 2009 – wissenschaftliches Programm
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HL: Fachverband Halbleiterphysik
HL 49: Quantum dots: preparation and characterization
HL 49.7: Vortrag
Freitag, 27. März 2009, 12:00–12:15, BEY 81
Shape of InN quantum dots and nanostructures grown by MOVPE — •S. Ploch1, Ch. Meissner1,2, M. Pristovsek1, and M. Kneissl1 — 1TU Berlin, Institut für Festkörperphysik, EW 6-1, Hardenbergstr. 36, 10623 Berlin — 2ISAS - Institute for Analytical Sciences, Albert-Einstein-Str. 9, 12489 Berlin
We report on the shape of InN quantum dots (QDs) grown on GaN/sapphire by MOVPE (metal organic vapour phase epitaxy) investigated by atomic force microscopy (AFM). The InN QDs were grown in a 100 mbar N2 atmosphere, with a TMIn partial pressure of 0.17 Pa, a V/III ratio of 15,000 and a growth temperature between 480∘C and 590 ∘C for 60 s. X-ray diffraction suggested pure relaxed InN. Only single large nanostructures and a low density are suitable for AFM investigations due to convolution with the AFM tip. Mesa shaped and cone like structures are observed. With increasing growth temperatures the cone type structures prevail. The mean height varies between 15 nm and 40 nm for mesa and 70 nm for conic structures. The mean diameter increases with increasing temperature from 70 nm at 550∘C to 230 nm at 590∘C for both structure types. The density is 2·108/cm2 over 560∘C. The mesa type structures exhibit a hexagonal footprint, the cone‘s footprint is more distorted. The different structure types have different side facets. For both structures {1102} and {1102} side facets dominate. No preferred facet polarity was observed for any facet. Two different explanations are possible for the different structures basing on a different growth rate caused by dislocations or a polarity inversion.