In an $n$-type semiconductor, the Fermi energy level lies

$A$ donor atom in a semiconductor has a loosely bound electron. The orbit of this electron is considerably affected by the semiconductor material but behaves in many ways like an electron orbiting a hydrogen nucleus. Given that the electron has an effective mass of $0.07 \, m_e$,where $m_e$ is the mass of the free electron,and the space in which it moves has a permittivity of $13 \, \varepsilon_0$,then the radius of the electron's lowermost energy orbit will be close to ................. $\mathring{A}$ (take the Bohr radius of the hydrogen atom as $0.53 \mathring{A}$).

$A$ pure $Si$ crystal has $4 \times 10^{28}$ atoms per $m^3$. It is doped with $1 \text{ ppm}$ concentration of antimony. The number of free electrons available will be

The width of the forbidden gap in a silicon crystal is $1.1 \, eV$. When the crystal is converted into an $N$-type semiconductor,the distance of the Fermi level from the conduction band is:

Suppose an $n$-type wafer is created by doping $Si$ crystal having $5 \times 10^{28} \text{ atoms/m}^3$ with $1 \text{ ppm}$ concentration of $As$. On the surface,$200 \text{ ppm}$ Boron is added to create a $p$-region in this wafer. Considering $n_i = 1.5 \times 10^{16} \text{ m}^{-3}$,$(i)$ Calculate the densities of the charge carriers in the $n$ and $p$ regions. $(ii)$ Comment on which charge carriers would contribute largely to the reverse saturation current when the diode is reverse biased.

$A$ pure semiconductor crystal has $5 \times 10^{22}$ atoms per $cm^3$. It is doped by $1$ ppm concentration of pentavalent element. The number of holes in the doped semiconductor is (given that $n_i = 1.5 \times 10^{10} cm^{-3}$):