Indium nitride quantum dot growth modes in metalorganic vapour phase epitaxy

We have investigated growth of InN quantum dots (QDs) on GaN (0 0 0 1) in metalorganic vapour phase epitaxy as a function of growth temperature, trimethylindium partial pressure, and growth time. The growth was analysed in situ by spectroscopic ellipsometry and ex situ by X-ray diffraction and atomic force microscopy. The QDs were found for all growth temperatures between 480 °C and 600 °C and for all growth times. The density increased exponentially with decreasing growth temperature, up to 1011cm-2 for 500 °C. By changing the amount of deposited material it was possible to control the size of the QDs. Above 530 °C a reduction of the effective growth rate was also observed. Reducing the V/III ratio by trimethylindium partial pressure from 15,000 to 5000 led to an increase in the growth rate. Both effects are due to reduced etching of the InN QDs by ammonia.