Berlin 2008 – wissenschaftliches Programm

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DS: Fachverband Dünne Schichten

DS 9: Semiconductor Nanophotonics: Materials, Models, Devices - GaN based Photonics II

DS 9.3: Vortrag

Montag, 25. Februar 2008, 16:45–17:00, H 2032

MOVPE grown Indium Nitride Quantum Dots — •C. Meißner^1,2, S. Ploch¹, M. Pristovsek¹, and M. Kneissl¹ — ¹Institut für Festkörperphysik, Technische Universität Berlin, Hardenbergstr. 36, EW6-1, 10623 Berlin — ²ISAS - Institute for Analytical Sciences, Albert-Einstein-Str. 9, 12489 Berlin

Very little attention has been devoted to the growth of indium nitride quantum dots (InN QDs) despite a number of interesting applications, e.g. in infrared emitters or solar cells. We studied the growth of InN QDs on GaN/sapphire templates in a horizontal metalorganic vapor phase epitaxy (MOPVE) reactor investigated by in-situ spectroscopic ellipsometry (SE). The temperature, V/III ratio and growth time were systematically varied during InN quantum dot growth. In-situ ellipsometry allows us to observe the growth processes even for submonolayer coverages. After growth the samples were investigated by standard characterization methods like atomic force microscopy, high resolution x-ray diffraction and photoluminescence.

Our studies showed that growth temperatures between 500^∘C and 550^∘C and V/III ratios above 5000 yield quantum dot like structures. Immediately after TMIn flow is switched off the ellipsometry-transients exhibit a clear dip, what can be attributed to desorption of excess Indium or a ripening process. At lower growth temperatures the QD density increases to 10¹¹ cm⁻² while the size decreases with mean height of a few nanometer and diameters as small as 16 nm. We will also discuss first experiments to overgrow the InN QDs with a GaN layer, which is a prerequisite step for the application of QDs in optical devices.