InGaN composition and growth rate during the early stages of metalorganic chemical vapor deposition

Transmission electron microscopy (TEM) and photoluminescence (PL) spectrosc opy were applied to study the metalorganic chemical vapor deposition of InG aN and the correlation between the structural properties and luminescence o f GaN/InxGa1-xN-quantum well structures. A series of samples was grown vary ing only the growth duration for the InGaN under otherwise unaltered growth conditions. Composition analyses were carried out by measuring local latti ce parameters from TEM images, which are directly related to the local In c oncentration. A rising average In concentration from 6.5% to 15.4% and a de creasing growth rate are observed with increasing growth duration. All samp les show an inhomogeneous In distribution containing In-rich agglomerates w ith a size of only a few nanometers and less pronounced composition fluctua tions on a scale of some 10 nm. The redshift of the PL peak energy with inc reasing quantum well thickness indicates that the luminescence is predomina ntly determined by the piezoelectric field. (C) 2001 American Institute of Physics.