When the conductivity of a semiconductor is only due to the breaking of the covalent bonds,the semiconductor is called

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

$A$ pure silicon crystal at temperature $300 \text{ K}$ has electron and hole concentration $(n_i) = 10^{16} \text{ per m}^3$ each. If $10^{21}$ phosphorus atoms $(n_D)$ are added per cubic metre, what is the new hole concentration in the silicon crystal?

At room temperature,a $p$-type semiconductor has

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

$A$ pure $Si$ crystal has $5 \times 10^{28}$ atoms $m^{-3}$. It is doped with $1 \, ppm$ concentration of pentavalent $As$. The number of holes is (Take $n_i = 1.5 \times 10^{16} \, m^{-3}$)