In a semiconductor,the intrinsic carrier concentration of electrons and holes is $6 \times 10^8 \ m^{-3}$. After doping with some impurity,the electron concentration increases to $9 \times 10^{12} \ m^{-3}$. Find the new hole concentration.

$A$ $P$-type semiconductor has acceptor levels $57 \; meV$ above the valence band. The maximum wavelength of light required to create a hole is (Planck's constant $h = 6.6 \times 10^{-34} \; J \cdot s$, speed of light $c = 3 \times 10^8 \; m/s$)

Which one of the following statements is true? $A$ p-type semiconductor is doped with

If $N_h$ and $N_e$ are the numbers of holes and conduction electrons in an extrinsic semiconductor,respectively,then:

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.

Write the difference between intrinsic and extrinsic semiconductors.