Method of manufacturing radiation-emitting semiconductor devices

Abstract

Radiation-emitting semiconductor diodes in the form of diode lasers or LEDs are used inter alia in information processing systems. There is a particular demand for diodes having a low wavelength. A diode laser which emits at 633 nm is a particularly attractive alternative to a helium-neon gas laser. According to the invention, a method of making a the buffer layer of such a radiation-emitting semiconductor diode comprises aluminium-gallium arsenide, the aluminium content having at least a minimum value belonging to the band gap of the active layer. The minimum Al content is approximately 6 at % for an InGaP band gap of 1.88 eV, and approximately 9 at % for 1.92 eV. As a result, an active layer comprising InGaP emits, for example, at 650 nm while the semiconductor layers still possess a good crystal quality and morphology. When the active layer of a diode laser has a multiple quantum well structure with comparatively thick (approximately 5 nm) well layers, it even emits at 633 nm. In this method according to the invention, a comparatively high growing temperature--preferably approximately 760.degree. C.--and a buffer layer comprising AlGaAs with a suitable aluminium content are used. Ordering of the structure in semiconductor layers comprising InGaP and InAlGaP is counteracted by this.