Semiconductor laser having a metal-filled groove for improved cooling and stability

A semiconductor laser having a semiconductor body comprising at least a first passive semiconductor layer of a first conductivity type, an active semiconductor layer disposed thereon and a second passive semiconductor layer of a second, opposite conductivity type disposed on said active layer, a pn junction between the first and the second passive layers and a groove on the side of said second passive layer in the surface of said semiconductor body, which groove extends at most over only part of the thickness of said second passive layer, upon the application of a voltage in the forward direction across the pn junction by electrode means, coherent electromagnetic radiation being produced in a strip-shaped part of said active layer lying below said groove and situated between two reflecting side faces of said semiconductor body substantially at right angles thereto, for which radiation said passive layers have a lower refractive index than said active layer, characterized in that said groove is filled selectively with a metal at least up to the level of said surface and in that on both sides of said metal an electrically substantially insulating region is present which adjoins said metal and extends from the surface over part of the thickness of said second passive layer.