PROBLEM TO BE SOLVED: To emit radiation with high emission efficiency by a structure wherein the device includes a cavity having an active layer emitting radiation, the cavity has a space for confining radiation and the device includes a one or more edge having a substantially random diffraction grating structure. SOLUTION: A region (active layer) 10 where charge carriers encounter to emit radiation has irregular surface structure 122 of substantially random diffraction grating structure where surface recoupling may take place. More specifically, the radiation emitting device has a cavity including a radiation confining space for confining charge carriers in a sub-space in the cavity smaller than the radiation confining space. The device has a cavity including at least one mesa edge of substantially random diffraction grating structure for defining the radiation confining space.