SEMICONDUCTOR DIODE LASER AND METHOD OF MANUFACTURING SAME

摘要

The invention relates to a laser with a (M)QW (=(Multi) Quantum Well) active layer (2) in which a portion (2A) of the quantum well (2A) and barrier layers (2B, 2C) is provided with a compression stress, while another portion (2B, 2C) is provided with an oppositely directed tensile stress. Said stresses are so dosed in the known laser that they compensate one another and the laser accordingly has substantially no net stress, so that the constituent stresses may be comparatively high without fatal defects arising in the laser owing to the stress. A disadvantage of the known laser is that it nevertheless shows premature degradation, especially when the emission wavelength is low, for example < 0.7 mu m, and the power is high. Said stresses in a laser according to the invention are overcompensated such that the net stress is a tensile stress. On the one hand, the advantages of compensation are sufficiently enjoyed, while on the other hand the surprising advantage arises that the generated radiation is absorbed to a lesser degree near the end faces (30) of the laser. The so-called end face or mirror degradation is considerably lower as a result. The resulting laser accordingly has a longer useful life than does the known laser. The invention is based on the recognition that relaxation of the stresses occurs near the end faces (30) and that, given an excess tensile stress, the relaxation results in an increased bandgap adjacent the end faces (30). Radiation absorption is decreased thereby. The invention also relates to a method of manufacturing a laser according to the invention. Preferably, the laser according to the invention comprises one or several quantum well layers (2A) with a compression stress and a number of barrier layers (2B, 2C) with an excess tensile stress. The invention offers the greatest advantage in short-wave lasers manufactured, for example, in the GaAs/InGaP/InAlGaP material system.