They haven't figured out how to get a reliable p-type device on this chip. It therefore won't compete for complementary logic at present. However I am sure there are some markets that they will compete in. They also use Si as a base layer, and build the GaN onto this. I assume this therefore has a cost implication when compared to PTK build costs?

I did email the author and he was not aware of POET. I asked him to forward details to the owner of EPC, Alex Lidow, to get his view. But at present have not heard from him.