If $N_A$ is the number density of acceptor atoms added and $N_D$ is the number density of donor atoms added to a semiconductor,and $n_e$ and $n_h$ are the number density of electrons and holes in it,then:

Explain $n$-type and $p$-type semiconductors based on energy band theory.

$A$ 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 .......... $A$.

In $N$-type semiconductors,the majority charge carriers are

In a semiconductor,the number densities 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:

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