71.

A photodetector used to detect the wavelength of 1700 nm, has energy gap of about

• 0.073 eV

• 1.2 eV

• 0.73 eV

• 1.16 eV

The energy gap between conduction band and the valence band is of the order of 0.7 eV. Then it is

• an insulator

• a conductor

• a semiconductor

• an alloy