At the present time, Si-based technology is undergoing a transition to the next generation of substrates, having a diameter of 300 mm. The fundamental physical limits are being approached in terms of miniaturization, increased chip area, faster switching speeds, and diversity of operations. This raises the question of the intrinsic limits of the currently predominant semiconductor, silicon, and of those circumstances where it may be advantageous to turn to materials such as GaAs, InP, or SiC.