Abstract: A radiation-emitting semiconductor diode in the InGaP/InAlGaP material system having a barrier for charge carriers situated between the active layer and one of the cladding layers. Such a diode has an emission wavelength between 0.6 and 0.7 .mu.m and is particularly suitable, when constructed as a diode laser, for serving as a radiation source in, for example, a system for reading and/or writing of optical discs, also because of an increased efficiency. The diode includes a barrier layer comprising only a single barrier layer of AlP, which can be manufactured with a good reproducibility and high yield. A thin AlP barrier layer, having a thickness less than 5 nm, for example 2.5 nm, still provides an excellent barrier.

Abstract: A diode laser present in an gas or vacuum atmosphere. The semiconductor body of the diode laser comprises two end faces which bound the resonant cavity within which radiation is generated in an active region. The active region forms part of an active layer situated between two cladding layers on a substrate. At least one end face is coated with a covering layer. The covering layer comprises at least two sub-layers of a first dielectricum with a first refractive index and of a second dielectricum with a second refractive index, respectively, and the optical thicknesses and refractive indices of the sub-layers are chosen such that the maximum intensity of the field strength of the generated radiation in the semiconductor body and the covering layer lies outside the end face, and preferably such that the intensity of the field strength of the generated radiation is approximately a minimum adjacent the end face. Preferably, the covering layer comprises two or three sub-layers of dielectric materials such as Al.

Abstract: The invention relates to a laser with a multi quantum well active layer in which a portion of the quantum well and barrier layers is provided with a compression stress, while another portion is provided with an oppositely directed tensile stress. Said stresses are overcompensated such that the net stress is a tensile stress. Preferably, the laser comprises one or several quantum well layers with a compression stress and a number of barrier layers with an excess tensile stress.