Features of InN growth by nitrogen-plasma-assisted MBE at different ratios of fluxes of group-III and -V elements

Abstract

The results of investigations of the effect of the ratios of fluxes of the Group-III and -V elements on the structural and optical properties of an InN film deposited by plasma-assisted molecular-beam epitaxy (MBE) are presented. It is shown that the InN layer consists of free-standing nanocolumns at a flux ratio of III/V < 0.6. InN growth becomes two-dimensional (2D) in the ratio range 0.6 < III/V < 0.9; however, the InN layer has a nanoporous structure. Upon passage to metal-rich conditions of growth (III/V ∼1.1), the InN layer becomes continuous. The passage from 3D to 2D growth is accompanied by an increase in the threading-dislocation density. It results in a decrease in the photoluminescence (PL) intensity of InN at room temperature. The electron concentration in the InN layers amounts to ∼5 × 10¹⁸ cm^–3, which results in a shift of the PL-signal peak to the wavelength region of 1.73–1.8 μm and to a shift of the absorption edge to the region of ∼1.65 μm.