Plasma-assisted MBE growth and characterization of InN on sapphire

• We report on a close correlation between the growth conditions of InN/Al2O3 (0 0 0 1) epilayers grown by plasma-assisted molecular beam epitaxy (MBE), their optical properties in the IR range, and the In clustering in the layers. High-spatial resolution techniques, namely micro-cathodoluminesesence, back-scattered electron imaging and energy dispersive X-ray analysis, were used to establish this correlation. The In-rich growth conditions, achieved by increasing either the growth temperature or the effective In/N flux ratio, causes the In clustering in InN, responsible in our samples for the 0.7-0.8 eV luminescence and IR optical absorption. Growth under In/N = 1: 1 conditions slightly shifted to the N-rich side generally produces InN layers without visible In clusters, having an optical absorption edge around 1.4 eV. A possible mechanism of In cluster formation is suggested on the basis of thermodynamic considerations for InN MBE growth. (C) 2004 Elsevier B.V. All rights reserved.

Nyckelord

growth models

morphological stability

optical spectroscopy

molecular beam epitaxy

InN

semiconducting indium compounds

TECHNOLOGY

TEKNIKVETENSKAP

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