In a III-nitride light emitting device, the device layers including the
light emitting layer are grown over a template designed to reduce strain
in the device, in particular in the light emitting layer. Reducing the
strain in the light emitting device may improve the performance of the
device. The template may expand the lattice constant in the light
emitting layer over the range of lattice constants available from
conventional growth templates. Strain is defined as follows: a given
layer has a bulk lattice constant a.sub.bulk corresponding to a lattice
constant of a free standing material of a same composition as that layer
and an in-plane lattice constant a.sub.in-plane corresponding to a
lattice constant of that layer as grown in the structure. The amount of
strain in a layer is |(a.sub.in-plane-a.sub.bulk)|/a.sub.bulk. In some
embodiments, the strain in the light emitting layer is less than 1%.