Application of compound semiconductors in telecommunication

Silicon is the only one material for the classical microelectronics applications such as analogue and digital integrated circuits including many applications in all the equipment used in our workplaces and homes. Special features of some of the compound semiconductors such as wide bandgap, high mobility, and direct bandgap are the basis for their application in different special areas. These applications are products of long research and development processes. The researchers were faced with serious technical and technological problems. Some of these materials are artificial and were only synthesised in this century. Raw materials used for the production of these semiconductors are dangerous and expensive. It means that for the realisation of a given electronic function the cost of a compound semiconductor device is 2....50 times higher than the same device based on silicon. The reliability factors are also weaker. Only the silicon can be produced defect-free, the compound semiconductor materials contain defects and different impurities. Some of the compounds cannot be used for producing p-n junctions. Because of the complicated chemical nature of these materials, the oxide covering the surface can not be used for photolithography and for producing MOS devices. Despite these drawbacks compound semiconductors are used increasingly in the communications arena, particularly in optoelectronics and HF systems (800 MHz 80 GHz)