Berlin 2005 – wissenschaftliches Programm

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HL: Halbleiterphysik

HL 55: Quantenpunkte und -dr
ähte: Herstellung und Charakterisierung II

HL 55.4: Vortrag

Dienstag, 8. März 2005, 15:45–16:00, TU P-N201

Structure and morphology of InGaN nano-islands on GaN studied by STM — •Subhashis Gangopadhyay, Thomas Schmidt, Sven Einfeldt, Tomohiro Yamaguchi, Detlef Hommel, and Jens Falta — Institute of Solid State Physics, University of Bremen, P. O. Box 330440, Bremen 28334, Germany

Scanning tunneling microscopy (STM) has been used to study the structure and morphology of InGaN nano-islands on GaN/Sapphire. InGaN islands were grown by metal organic vapor pressure epitaxy (MOVPE) for different choices of growth temperature, InGaN deposit, growth rate and III:V flux ratio. After growth, the samples were transferred to the UHV-STM analysis chamber under nitrogen ambient to suppress surface oxidation. Depending on the various growth parameters, three different types of InGaN islands are observed. The lateral size (diameter) of the islands was ranging from 15 nm to 100 nm whereas the height of the islands varied from 1 nm to 8 nm. The top of the larger islands (650^∘C growth temperature), appears very flat and a spiral disc-like growth with monolayer step-height was observed. Excess In was found in droplets preferentially on the top of the InGaN islands. For smaller islands (600^∘C growth temperature), homogeneously distributed island with high density were observed.