Graphene Won't Replace Silicon In CPUs, Says IBM 81
arcticstoat writes "IBM has revealed that graphene can't fully replace silicon inside CPUs, as a graphene transistor can't actually be completely switched off. In an interview, Yu-Ming Lin from IBM Research (Nanometer Scale Science and Technology) explained that 'graphene as it is will not replace the role of silicon in the digital computing regime.' Last year, IBM demonstrated a graphene transistor running at 100GHz, while researchers at UCLA produced a graphene transistor with a cut-off frequency of 300GHz, prompting predictions of silicon marching towards its demise, making way for a graphene-based future with 1THz CPUs. However, Lin says, 'there is an important distinction between the graphene transistors that we demonstrated and the transistors used in a CPU. Unlike silicon, graphene does not have an energy gap, and therefore, graphene cannot be "switched off," resulting in a small on/off ratio.' That said, Lin also pointed out that graphene 'may complement silicon in the form of a hybrid circuit to enrich the functionality of computer chips.' He gives the example of RF circuits, which aren't dependent on a large on/off ratio."
Meanwhile... (Score:5, Insightful)
Re:Congratulations (Score:4, Insightful)
You can't switch off silicon either. You can turn it down quite a bit so it's almost off, but it's not like it's a magic box that shuts off completely and turns on instantly when you supply exactly 0.7V across the base.
You are confusing MOSFETS with BJTs.
BJT transistors have small threshold voltages such as 0.7V, however you cannot say exact for any transistor. The threshold voltage fluctuates with many material properties, temperature, and the voltage applied across the main current path (collector to emitter for BJTs, drain to source for MOSFETS) of the device.
Aside from that, its nice to take the engineers view of the world. If the 'off ' state is several orders of magnitude less conductive than the 'on ' state, then it is pretty much off. In the case of graphene, the conduction ratio for on/off is much smaller than that seen in silicon.
Final note: nothing in the world happens instantly! (except in quantum physics, where magic is just a statistical possibility)
Re:Ya well don't get too excited (Score:2, Insightful)
You just need to think fourth dimensionally.
Just because stuff can't get across the chip in one cycle doesn't mean it's useless, it just means we have to rethink how we do computing at that level.
Whether this means your "pipeline" is actually just a wire, or whatnot. The fact that there is a new problem doesn't mean we throw our hands in the air and give up.