Carbon, silicon, and germanium have four valence electrons each. These are characterized by valence and conduction bands separated by the energy bandgap respectively equal to \((E_g)_C, (E_g)_{Si}~\text{and}~(E_g)_{Ge}\). Which of the following statements is true?
1. | \((E_g)_{Si} < (E_g)_{Ge}<(E_g)_{C}\) |
2. | \((E_g)_{C} < (E_g)_{Ge}>(E_g)_{Si}\) |
3. | \((E_g)_{C} > (E_g)_{Si}>(E_g)_{Ge}\) |
4. | \((E_g)_{C} =(E_g)_{Si}=(E_g)_{Ge}\) |
In an intrinsic semiconductor, the energy gap \(E_g\) is \(1.2~\text{eV}.\) Its hole mobility is much smaller than electron mobility and independent of temperature. What is the ratio between conductivity at \(600~\text{K}\) and that at \(300~\text{K}?\)
(assume that the temperature dependence of intrinsic carrier concentration \(n_{i}\) is given by; \(n_{i} = n_{0} \exp \left[\frac{- E_{g}}{2 k_{B} T}\right] ,\)where \(n_0\) is the constant)
1. \(1.01\times10^6:1\)
2. \(1.09\times10^5:1\)
3. \(1:1\)
4. \(1:2\)