Can we use carbon instead of silicon?
The reason silicon was used is because it formed a stable, tenacious oxide, was plentiful and cheap. The other Group IV elements didn’t have ALL these properties. It turns out that and easy to form oxide is important for transistor gates and for use as an insulator. Carbon, when combined with oxygen, forms a gas, not an solid oxide, so carbon isn’t a good starting element. Silicon is a semi-conducting metal; carbon doesn’t have the common metallic properties associated with metals (such as being ‘shiny’); carbon also isn’t that abundant, certainly not compared to silicon; it also has a small atomic diameter, so doesn’t even come close to matching the lattice dimensions of metals – this makes it difficult to dope or attach conductors to the crystal – just not a practical material. Germainium is better, and has favorable work function – it just doesn’t form a good quality oxide. It turns out that the latest technology (22nm) is abandoning silicon oxide for gate insulators in favor of HfO
