The state of the energy gained by valence electrons when the temperature is raised or when an electric field is applied is called as:

The resistivity of a semiconductor depends on $........$.

When a semiconductor is heated,its resistance

Carbon,Silicon,and Germanium atoms each have four valence electrons. If their bandgaps are represented by $(E_g)_C$,$(E_g)_{Si}$,and $(E_g)_{Ge}$ respectively,which of the following relations is correct?

The forbidden energy gap in $Ge$ is $0.72\,eV$. Given,$hc = 12400\,eV\cdot\mathring{A}$. The maximum wavelength of radiation that will generate an electron-hole pair is..........$\mathring{A}$.

Explain by drawing the energy levels of $Si$ and $Ge$ containing $N$ atoms at $0\, K$ temperature.