A semiconductor light emitting device includes an n-type region, a p-type region, and light emitting region disposed between the n- and p-type regions. The n-type, p-type, and light emitting regions form a cavity having a top surface and a bottom surface. Both the top surface and the bottom surface of the cavity may have a rough surface. For example, the surface may have a plurality of peaks separated by a plurality of valleys. In some embodiments, the thickness of the cavity is kept constant by incorporating an etch-stop layer into the device, then thinning the layers of the device by a process that terminates on the etch-stop layer.