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

In a $p$-type semiconductor,

$A$ $N-$ type semiconductor is

The impurity atoms which are mixed with pure silicon to make a $P$-type semiconductor are those of:

When a small amount of impurity atoms are added to a semiconductor,then generally its resistivity

In a semiconductor,the concentrations of electrons and holes are $8 \times 10^{18} \, m^{-3}$ and $5 \times 10^{18} \, m^{-3}$ respectively. If the mobilities of electrons and holes are $2.3 \, m^2/V \cdot s$ and $0.01 \, m^2/V \cdot s$ respectively,then the semiconductor is: