U.S. Philips Corporation

Michael J Boermans

Adriaan Valster

Carolus J Van Der Poel

Radiation-emitting semiconductor diodes are used inter alia in information processing systems as diode lasers or LEDs. Such a radiation-emitting semiconductor diode including an active layer situated between two cladding layers, which layers each include a mixed crystal of III-V semiconductor materials, atoms of different elements, often having a certain degree of ordering, being present on at least one sublattice. An example is an InGaP/InAlGaP diode laser which emits at 670 nm and is highly suitable for various applications. There is a particular demand for diodes which have a high maximum operating temperature at a given wavelength. According to the invention, the composition of the semiconductor material of the active layer is so chosen that this layer has a compression strain, while the atoms of the different elements have a less orderly distribution at least in the semiconductor material of the active layer. This strongly reduces the starting current, while the emission wavelength remains substantially unchanged. In a preferred embodiment, the distribution in the semiconductor materials of the cladding layers is also less orderly, which improves the confinement and thus the temperature dependence characteristics of the starting current. The maximum operating temperature of diode lasers according to the invention is considerably increased owing to a low starting current and a low temperature dependence of this starting current.

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Eindhoven, Netherlands

Michael J Boermans