Abstract: A thin film resistor for optoelectronic integrated circuits is described. A stable low resistance, thin film resistor comprising a bilayer of platinum on titanium is provided. Advantageously, the resistive layer is protected by a layer of dielectric, e.g. silicon dioxide or silicon nitride to reduce degradation from humidity an under high temperature operation at 300.degree. C. or more. The resistor may be formed on various substrates, including silicon dioxide, silicon nitride and semiconductor substrates. Applications for optoelectronic integrated circuits include integrated resistive heaters for wavelength fine tuning of a semiconductor laser array.

Abstract: A method of accurately controlling the depth of etched gratings in uniform or layered quaternary III-V material. A native oxide is selectively grown on the area of the quaternary to be patterned and this native oxide is subsequently removed to engrave the surface. Periodic repetition of the oxide growth/removal steps results in gratings of the desired depths.

Abstract: Zinc is diffused into indium phosphide in the presence of cadmium to prevent degradation of the indium phosphide surface.

Abstract: In the manufacture of double heterostructure laser diodes using liquid phase epitaxy a source crystal precedes the laser substrate crystal through the process to ensure saturation of the various melts from which epitaxial growth is obtained. The source crystal has hitherto been discarded. The source crystal, since it immediately precedes the substrate crystal, also experiences epitaxial growth of a heterostructure but with heterostructure layer thicknesses unsuited for laser diode fabrication. By suitable processing of the source crystal after it is formed with a heterostructure, light emitting diodes can be produced so contributing to a 50% reduction in materials cost.