Abstract
InyAl1?yN epifilms with alloy compositions (y) ranging from 0.13 to 0.47 were grown on a GaN template using a low-temperature molecular-beam-epitaxy technique. Because of the larger lattice constant of high-indium-content InyAl1?yN epifilm, the compressive stress accumulated during epitaxy. When the compressive stress exceeded the elastic limit of the InyAl1?yN epifilms, a “concave-valley” crack with an equivalent width (~25 nm) was generated to form a prismatic domain. Our calculation and fitting results showed that no cracking occurred when the lattice mismatch was<1% because the stress was within the elastic limit. By contrast, the cracks appeared when the lattice mismatch was>2.4% because the stress exceeded the elastic limit.
NSTL
Elsevier