Heteroepitaxial growth of InN islands studied by STM and AFM

Heteroepitaxial growth of InN on GaN(0001) and on Si(111) has been studied using scanning tunnelling microscopy (STM) and atomic force microscopy (AFM) in order to elucidate the growth modes. Using cracked ammonia as group V source, InN/GaN grows in a two-dimensional mode, despite the fact that there is an 11.2% lattice mismatch. Only a pre-exposition of the GaN substrate to silicon enables a growth mode change from two-dimensional to three-dimensional. When we deposit indium in a cracked ammonia environment on Si(111), we again observe two-dimensional growth with small islands of varying size. Surface reconstructions on the islands have been observed with atomic resolution. However, we believe that atomic hydrogen, a cracking product of ammonia, prevents the growth of InN and the observed reconstructions are indium adsorbate structures on Si(111).