GaAs has an energy gap of 1.43 eV. The optical cut-off wavelength

GaAs has an energy gap of 1.43 eV. The optical cut-off wavelength of GaAs would lie in the:

1. visible region of the spectrum
2. infrared region of the spectrum
3. ultraviolet region of the spectrum
4. far ultraviolet region of the spectrum

GaAs has an energy gap of 1.43 eV. The optical cutoff wavelength of GaAs would lie in the infrared region of the spectrum.