The path for silicon materials development has been charted. By the year 2010 we will have fabricated integrated circuit chips containing 109 transistors with 40 Å thick gate oxides and 1000 Å minimum feature sizes running at 4 GHz clock speeds. It is conceivable that incremental advances on the current chip architecture will satisfy the required materials and process improvements. The interconnection problem is the only challenge without a proposed solution. The signal propagation delay between devices is now longer than the individual device gate delay. The resistance and capacitance associated with fine line Al interconnects limit speed and increase power consumption and crosstalk. High power line drivers are limited by the reliability constraint of electromigration. There is no current paradigm for 4 GHz, electronic clock distribution. Optical interconnection can remove the electronic transmission bandwidth limit. The main challenge is development of a silicon-compatible, microphotonic technology.
Rare earth doping has provided a means of sharp-line electroluminescence from silicon at λ = 1.54 μm. Silicon's high index of refraction and low absorption in the near infrared yield an ideal optical waveguide. As with microelectronics, the silicon / silicon-dioxide materials system allows high levels of integration and functionality. The applications of silicon materials to light emission (Si:Er), optical waveguides (Si/SiO2), photonic switching (Si/SiO2) and photon detection (SiGe) are reviewed. These developments are discussed in the context of systems applications to communications and computation.