Features of the spatial distribution of indium in InGaN epitaxial layers grown by plasma-assisted molecular beam epitaxy

Abstract

The processes leading to the formation of a spatially nonuniform distribution of indium in the InxGa1 − x N layers with x = 0−0.6 grown by molecular beam epitaxy with plasma activation of nitrogen at relatively low growth temperatures (590–630°C) are studied. It is found that at low values of x < 0.1, the growth proceeds pseudomorphically at least to a thickness of 70 nm, and these layers are characterized by a high uniformity of the In distribution, which confirms their thermodynamic stability. Upon increasing x up to ∼0.3, the signs of a nonuniform In distribution are observed, which is associated with the stress relaxation facilitating the development of phase separation. It is shown that layers with In distribution of lower uniformity feature more intense photoluminescence in the energy range 2.0–2.5 eV. For the layers with x = 0.6, complete phase separation is observed with the formation of several phases with a wide range of compositions, including the region in the vicinity of the InN binary compound.