Stranski‐Krastanov Growth of InN Nanostructures on GaN Studied by RHEED, STM and AFM

The growth of self-assembled InN nanostructures on GaN by MBE has been studied using two different nitrogen sources. Stranski-Krastanov growth may be achieved but is highly sensitive to the V:III ratio as well as coverage and temperature. The size and shape of the resultant nanostructures depend on the nitrogen source used. Using thermally cracked ammonia, Stranski-Krastanov growth occurred only for thin layers (up to 8 monolayers) at high V:III ratios, as observed by RHEED and AFM. The sensitivity of the growth to the V:III ratio may be explained in terms of the interplay between equilibrium thermodynamics and growth kinetics. Similar experiments at higher V:III ratios were performed using a modified nitrogen plasma source. Stranski-Krastanov growth occurred and was observed in-situ by RHEED. The as-grown nanostructures were imaged in-vacuo by elevated-temperature STM, showing the dependence of island size and distribution on the InN coverage.