What is the maximum wave length of EM radiation required to move an electron from the valance band to conduction band of a semiconductor? [Given :Energy gap $\mathrm{E}_{\mathrm{g}}=1.98 \times 10^{-19} \mathrm{~J}$; Planck's constant $h=6.6 \times 10^{-34} \mathrm{Js}$ ]

A Si and a Ge diode has identical physical dimensions. The band gap in Si is larger than that in Ge. On applying identical reverse bias across these diodes,

The electrical conductivity of a semiconductor increases when electromagnetic radiation of wavelength shorter than $1.24 \mu \mathrm{~m}$ is incident on it. The band gap (in eV ) for the semiconductor is

In the energy band diagram of a material shown below, open circles and filled circles denote holes and electrons respectively. The material is a