Growth kinetics and nanoscale structure-property relationships of InN nanostructures on GaN(0 0 0 1)

Abstract

The effects of growth rate on the structural, morphological, and electrical properties of InN nanostructures grown on [0001]-oriented GaN substrates by plasma-assisted molecular beam epitaxy is reported. Slowing the growth rate of the nanostructures resulted in extended time for reaching thermodynamically favored crystal facet structures, while at the same time extended the time during which the rf growth plasma can foster damage to the growth. Nanoscale mapping of surface potential and current transport were performed by Kelvin probe force microscopy (KPFM) and conductive atomic force microscopy (C-AFM). The results show that increasing the growth rate by ~2.5 times results in more pronounced {10–15} facets of InN nanostructures and decreasing of the residual electron concentration from ~5.8 · 1017 cm−3 to ~2.5 · 1017 cm−3. This is explained by the direct bombardment of indium nitride with plasma species and enhanced decomposition, desorption of adatoms, and an increase in surface dangling bonds that creates surface states traps for electrons. The phenomena of electron accumulation in the near-surface region, as well as the current-voltage hysteresis curves under forward biases for InN nanostructures on GaN(0 0 0 1) substrate are disused.