Influence of temperature on atomic layer epitaxial growth of indium nitride assessed with in situ grazing incidence small-angle x-ray scattering

Abstract

The surface topological evolution during the growth of indium nitride (InN) by plasma-assisted atomic layer epitaxy (ALEp) on gallium nitride (GaN) (0001) substrates was studied using in situ real-time grazing incidence small-angle x-ray scattering (GISAXS) for 180, 250, and 320 °C growth temperatures. The GISAXS data reveal that the ALEp growth of InN on GaN in this temperature range proceeds in a Stranski–Krastanov mode, in which the 2D–3D transition occurred after 2.3 monolayers for 180 °C, 1 monolayer for 250 °C, and 1.5 monolayers for 320 °C. The corresponding initial island center-to-center distances were 7.4, 11.6, and 11.7 nm. Additionally, island coarsening was observed to increase with temperature. After 200 growth cycles, the mean island diameters were 3.9, 5.6, and 7.0 nm, and the mean island center-to-center distances were 8.6, 13.7, and 17.1 nm for 180, 250, and 320 °C growth temperatures, respectively. For the 320 °C growth, the mean island shape was observed to gradually evolve from relatively mounded to cylindrical. These results are supported by atomic force microscopy and specular x-ray reflectivity.

On the dynamics in chemical vapor deposition of InN

“…4 d and e), the averaged diameter of InN crystal grains is 9 nm. This result is comparable to the value of InN grown by ALD using N2 plasma on GaN surface as reported by Woodward et al 44 A finite inter distance (smaller than 7 nm) between particles together with high particle density of 7.5×10 11 cm -2 indicates that the InN crystal grains are homogeneously distributed on the surface (Fig. 4c).…”

“…The particle-like surface feature is likely due to a Stranski-Krastanov growth mode where 3D growth takes over after a critical thickness of approximately 1 nm, which has been experimentally verified. 44 The particle density, particle size and distance between particles can be used to depict the distribution of adsorbed In-species on the surface, which changes with time, reflecting their mobility. According to our analysis, the average particle size increases from 5 nm to 16 nm (Fig.…”

On the dynamics in chemical vapor deposition of InN

“…4 d and e), the averaged diameter of InN crystal grains is 9 nm. This result is comparable to the value of InN grown by ALD using N2 plasma on GaN surface as reported by Woodward et al 41 A finite inter distance (smaller than 7 nm) between particles together with high particle density of 7.5×10 11 cm -2 indicates that the InN crystal grains are homogeneously distributed on the surface (Fig. 4c).…”

“…In fact, our ALD work was done in a temperature range higher than the typical InN ALD window of 150-300 °C. 21,22,[38][39][40][41] Considering the difference in film deposition observed in Figs. 1 and 2 at different temperatures and the thermal stability of TMI, our ALD of InN is likely to involve several In-species.…”

“…The particle-like surface feature is likely due to a Stranski-Krastanov growth mode where 3D growth takes over after a critical thickness of approximately 1 nm. 41 The particle density, particle size and inter-particle distance can be used to depict the distribution of adsorbed In-species on the surface, which changes with time, reflecting their mobility. According to our analysis, the average particle size increases from 5 nm to 16 nm (Fig.…”