Solid State Physics Answers

a fixed mass of gas at costant presure has a volume of 100°c find its volume at temperature of 54°c

Question 5

 5.1​ The electron and hole mobilities in a Si sample are 0.135 and 0.48m²/V-s respectively. ​Determine the conductivities of intrinsic Si at 300 K if the intrinsic carrier concentration is 1.5x10⁶ atom/m³. The sample is then doped with 10²³ phosphorus atom/m³. Determine the equilibrium hole concentration, conductivity, and position of the Fermi level relative to the intrinsic level.​

5.2​ Indicate on an energy level diagram the conduction and valence bands, donor and acceptor states and the position of Fermi level for

(i) an intrinsic semiconductor.

(ii) a n-type semiconductor.

(iii) a p-type semiconductor.​

Question 3

 If the velocity of sound in a solid is of the order 10³ m/s, compare the frequency of the sound wave λ = 20 Å for (a) a monoatomic system and (b) acoustic waves and optical waves in a diatomic system containing two identical atoms (M=m) per unit cell of interatomic spacing 2.2 Å.​​​​​​

Question 4

 4.1 ​The conductivity of silver is 6.5 x10⁷ per Ohm per m and number of conduction electrons per m³ is 6x10²⁸ Find the mobility of conduction electrons and the drift velocity in an electric field of 1 V/m. Given m = 9.1 x 10^-31kg and e=1.602 x 10^-19C.​​​​​​​

4.2​ What is Lorentz number? The thermal and electrical conductivities of Cu at 20^oC are 390 Wm^-1K^-1 and 5.87x10⁷W^-1m^-1 respectively. Calculate Lorentz number.​​

Question 1​​​​​​​​​​​​

 Compute the net potential energy of a simple Na⁺Cl^- pair. The equilibrium distance between the ions is 0.28nm. The potential energy due to repulsion between electrons is given by U_r= β/r⁸

Question 2

2.1​ α-Co has an hcp structure with lattice spacings of a= 2.51 A^o and c = 4.07 A^o, β Co is fcc, with a cubic lattice spacing of 3.55 A^o. What is the difference in density between the two forms?​​

2.2​ Sodium transform from bcc to hcp at about T = 23K. Assuming that the density remains fixed, and the c/ a ratio isideal, calculate the hcp lattice spacing given that the cubic lattice spacing is  a' = 4.23 A^o in the cubic phase.      ​​​

​Indicate on an energy level diagram the conduction and valence bands, donor and acceptor states and the position of Fermi level for

(i) an intrinsic semiconductor.

(ii) a n-type semiconductor.

(iii) a p-type semiconductor.