Question

Metals are usually transparent because of their lack of a bandgap​

Answer 1

When this 'heavy' doping is done in an insulator whose band gap is greater than 3.0 eV, the material transmits most part of thevisible radiation with energy between 1.66 and 3.21 eV and hence is called as 'Transparent Conductors'. ... The transparentconducting metal oxides are also referred to as oxide semiconductors.