Indium adlayer kinetics on the gallium nitride (0001) surface: Monitoring indium segregation and precursor-mediated adsorption

Abstract

Indium kinetics and evidence for indium segregation on the GaN (0001) surface are investigated via in situ spectroscopic ellipsometry. Indium deposition exhibits two stable states at coverages of 1.0 and 1.7 ML within the temperature range of $630--688\phantom{\rule{0.2em}{0ex}}\ifmmode^\circ\else\textdegree\fi{}\mathrm{C}$. Formation of each layer is governed by two kinetic processes: nuclei formation and nuclei-mediated layer adsorption. The measured desorption activation energies of nuclei of the first $(2.04\phantom{\rule{0.3em}{0ex}}\mathrm{eV})$ and second $(2.33\phantom{\rule{0.3em}{0ex}}\mathrm{eV})$ monolayers are lower than the desorption activation energies of the aggregated first $(2.64\phantom{\rule{0.3em}{0ex}}\mathrm{eV})$ and second $(2.53\phantom{\rule{0.3em}{0ex}}\mathrm{eV})$ monolayers, respectively. This suggests that adatoms preferentially interact with the nuclei and laterally aggregate.