Just theory, not a problem. Is what differentiates a conductor from a semiconductor that the Fermi level has empty orbitals very close in energy to it so that electrons can be mobile in the conduction band? So what is the largest band gap you can have before you call the material a metal? Antimony and Tellurium would be the 2 most metallic "metal/non-metal hybrids," and I found that: "Antimony telluride (Sb2Te3) is a small bandgap semiconductor with a gap of 0.28 eV" So how much smaller before some compound would be considered a metal? And the focus of the differentiation between semiconductor/metal is the band gap right?