Conductivity, mobility, current density (drift & diffusion) in semiconductors(n type and p type)

Define super conductivity and critical temperature. Plot the variation of resistance versus temperature in case of superconducting state of the material. 

Define the term drift current and mobility of a charge carriers. Calculate the current product in a germanium sample of area of cross section 1 cm² and thickness of 0.01 m, when a potential difference of 2V is applied cross it. Given :- the concentration of free electron in germanium is 2×10¹⁹ /m³  and mobilities of electrons and holes are 0.36 m² /volts sec and 0.17 m² /volts sec respectively.

The mobility of holes is 0.025m² /V-sec. what would be the resistivity of n- type Si if the Hall coefficient of the sample is 2.25× 10^-5m³/C. 

Define drift current, diffusion current and P-N junction. The electrical conductivity of a pure silicon at room temperature is 4×10^-4 mho/m . if the mobility of electron is 0.14m² /V-S and that of hole is 0.04m² /V-S. calculate the intrinsic
carrier density.

Mobility of electron and hole in a sample of Ge at room temperature are 0.36 m² /V-sec and 0.17m² /V-sec respectively. If electron and holes densities are equal and it is 2.5 ×10¹³ /cm³ , calculate its conductivity.

Calculate electron & hole concentration in intrinsic Si at room temperature if
its electrical conductivity is 4x10-4 mho/m.Given that mobility of electron=
0.14m2/V-sec and  mobility of holes=0.04m2/V-sec.

Show that for intrinsic semiconductors of the Fermi level lies midway between the conduction band and the valence band .With the help of diagram explain effect of impurity concentration on Fermi level of N type semiconductor.