A semiconductor light emitting device includes a planar light emitting layer with a wurtzite crystal structure having a axis roughly parallel to the plane of the layer, referred to as an in-plane light emitting layer. The in-plane light emitting layer may include, for example, a {11 20} or {10 10} InGaN light emitting layer. In some embodiments, the in-plane light emitting layer has a thickness greater than 50 Å.