A method for fabricating a laser diode, comprises the steps of: forming a first stripe structure defined by a plurality of crystallographically distinct surfaces on a surface of a semiconductor substrate; forming an epitaxial layer of InGaAlP on the semiconductor substrate including the first stripe structure by a decomposition of gaseous source materials of In, Ga, Al and P; wherein the InGaAlP layer is doped to the p-type by incorporating Mg while growing the InGaAlP by adding a gaseous source material of Mg into said source materials of In, Ga, Al and P such that the InGaAlP layer is doped to the p-type with a substantially uniform carrier concentration level irrespective of the crystal surfaces forming the stripe structure.