A light-emitting device has a light-emitting layer of nitride semiconductor
containing As, P or Sb and accordingly its emission efficiency or emission
intensity is enhanced. The light-emitting device includes a substrate, and
further includes n-type and p-type nitride semiconductor layers and a
light-emitting layer between the n-type and p-type semiconductor layers
that are formed on the substrate. Light-emitting layer includes one or a
plurality of well layers formed of nitride semiconductor containing N and
element X (element X is As, P or Sb). The nitride semiconductor of the
well layer has at most 30% in atomic percent represented by expression
{N.sub.X /(N.sub.N +N.sub.X)}.times.100 where N.sub.X represents the
number of atoms of element X and N.sub.N represents the number of atoms of
N. The thickness of the well layer ranges from 0.4 nm to 4.8 nm.
