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

Pure Silicon crystal at $300 \ K$ has equal electron and hole concentration of $1.5 \times 10^{16} \ m^{-3}$. Doping by indium increases $n_h = 4.5 \times 10^{22} \ m^{-3}$. The $n_e$ in the doped silicon is:

In an $n$-type semiconductor,the free electrons donated by the impurity atoms occupy energy levels in:

An $n$-type and $p$-type semiconductor can be obtained by respectively doping pure silicon with

$A$ potential difference of $2.5 \,V$ is applied across the faces of a germanium crystal plate. The face area of the crystal is $1 \,cm^2$ and its thickness is $1.0 \,mm$. The free electron concentration in germanium is $2 \times 10^{19} \,m^{-3}$ and the electron and hole mobilities are $0.33 \,m^2/V \cdot s$ and $0.17 \,m^2/V \cdot s$ respectively. The current across the plate will be .......... $A$.

The typical ionisation energy of a donor in silicon is.....$eV$