Development of Cross-Hatch Morphology During Growth of Lattice Mismatched Layers
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Development of Cross-Hatch Morphology During Growth of Lattice Mismatched Layers A. Maxwell Andrews, J.S. Speck, A.E. Romanov1, M. Bobeth2 and W. Pompe2 Materials Department, University of California, Santa Barbara Santa Barbara, CA 93106-5050, U.S.A. 1 A.F.Ioffe Physico-Technical Institute, Russian Academy of Sciences St. Petersburg 194021, Russia 2 Technical University of Dresden Dresden 01609, Germany ABSTRACT An approach is developed for understanding the cross-hatch morphology in lattice mismatched heteroepitaxial film growth. It is demonstrated that both strain relaxation associated with misfit dislocation formation and subsequent step elimination (e.g. by step-flow growth) are responsible for the appearance of nanoscopic surface height undulations (0.1-10 nm) on a mesoscopic (~100 nm) lateral scale. The results of Monte Carlo simulations for dislocationassisted strain relaxation and subsequent film growth predict the development of cross-hatch patterns with a characteristic surface undulation magnitude ~50 Å in an approximately 70% strain relaxed In0.25Ga0.75As layers. The model is supported by atomic force microscopy (AFM) observations of cross-hatch morphology in the same composition samples grown well beyond the critical thickness for misfit dislocation generation.
INTRODUCTION In lattice mismatched semiconductor systems, large undulations in the surface height profile appear as a characteristic cross-hatch pattern, which can be revealed by atomic force microscopy (AFM), scanning tunneling microscopy (STM), and by optical Nomarski microscopy [1-4]. Cross-hatch morphology is a common feature for low mismatch (
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