Well Gallium-Arsenide, Indium-Phosphide and all kinds of other semi-conductors. But thing is, Silicon is well entrenched and there are work-arounds for all the

Well Gallium-Arsenide, Indium-Phosphide and all kinds of other semi-conductors. But thing is, Silicon is well entrenched and there are work-arounds for all the different shortcomings of silicone and really a lot of experience working with Si. So the theoretical advantage of different substances where never able to overcome the momentum Si has.