Dresden 2014 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 46: Nitrides: mostly structural characterization

HL 46.3: Vortrag

Dienstag, 1. April 2014, 12:15–12:30, POT 051

Influence of substrate material on InN island nucleation during double-pulsed PAMBE — •Andreas Kraus, Christopher Hein, Heiko Bremers, Uwe Rossow, and Andreas Hangleiter — Institut für Angewandte Physik, Technische Universität Braunschweig

Using pulsed and alternating source fluxes with In pulses less than one monolayer, we are able to grow huge and atomically flat InN islands. However, after a critical island diameter only partial coalescence takes place and In droplet formation occurs. In this contribution we present our investigations on InN island growth on different substrates. The influence of strain, sticking coefficient and surface morphology was studied by growing InN on pure c-oriented sapphire, nitridated sapphire (AlN/Al2O3) and MOVPE grown (0001) GaN/Al2O3 templates. Furthermore, the influence of dislocation densities was investigated by comparing growth on MOVPE GaN templates with dislocation densities of approximately 109 cm−2 and pseudo-bulk GaN with only 107 cm−2. The samples were characterized by AFM, SEM, RHEED and HRXRD. The results show the largest island aspect ratio for growth on Al2O3 a smaller one on AlN/Al2O3 and the smallest on GaN/Al2O3. The island density follows an opposite trend. Growth on (0001) GaN/Al2O3 templates leads to two different kinds of island shapes which are very smooth islands and spiral hillocks. The density of the latter one is much less on pseudo-bulk GaN substrates. Spiral hillocks and dendritic features at their rims are correlated with the hindered coalescence with adjoining islands. Therefore, using pseudo-bulk GaN is promising to achieve coalesced InN layers.

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