Abstract: A light emitting diode composed of a compound semiconductor containing aluminum having a GaAlAs layer and the like and having a structure which is superior in humidity resistance and has a long life. For example, in a double hetero light emitting diode constructed by comprising a p-GaAlAs layer, an n-GaAlAs layer, and an active layer interposed between both the GaAlAs layers, an oxide layer containing the oxide of gallium is provided inside of the surface excluding a portion where an electrode is provided of its semiconductor device, so that the surface of the device is stabilized. On the other hand, in the structure of a light emitting diode in which stepped portions are provided in the peripheral part of its semiconductor device, an oxide layer is provided inside of the surface of the device and inside of the peripheral part, and an insulating layer is formed on the oxide layer on the surface of the device.

Abstract: A semiconductor laser apparatus in which a laser emits light from a facet toward a photosensor having a light absorptive surface which is covered by a film having a reflectivity in the range of between about 60% to 90% to reflect light back to the laser with the remainder passing through to the light absorptive surface of the photosensor. The distance between the laser light emitting facet and the reflecting film is in the range of 50 to 150 .mu.m.