Bsc CSIT Semester 1 – Physics – Unit 5: Fundamentals of Solid State Physics (6 Hrs.)

Discuss single crystal growth by discussing following techniques:
$\quad$(a) Czochralski Method,
$\quad$(b) Bridgman-Stoclebarger Method,
$\quad$(c) Floating Zone Method and
$\quad$(d) Vapor-Phase Epitaxy.

The energy gaps of some alkali halides are KCl = 7.6 eV, KBr = 6.3 eV, KI = 5.6 eV. Which of these are transparent to visible light? At what wavelength does each become opaque?

Describe classical free electron model.

Give a brief account of Krongi-Penny model.

In neutron spectroscopy a beam of mono-energetic neutrons is obtained by reflecting reactor neutrons from a beryllium crystal. If the separation between the atomic planes of the beryllium crystal is 0.732 Å, what is the angle between the incident neutron beam and the atomic planes that will yield a monochromatic beam of neutrons of wavelength 0.1 A?

The density of aluminum is 2.70 g/cm3 and its molecular weight is 26.98 g/mole.

$\quad$ (a) Calculate the Fermi energy.
$\quad$ (b) If the experimental value of EF is 12 eV, what is the electron effective mass in alu-minum? [Aluminum is trivalent].

The density of aluminum is 2.70 g/cm3 and its molecular weight is 26.98 g/mole.

$\quad$ a. Calculate the Fermi energy

$\quad$ b. If the experimental value of EF is 12 eV, What is the electron effective mass in aluminum? Aluminum is

$\quad$ trivalent.

A current of 50A is supplied in a slab of copper 0.5cm thick and 2 cm wide is placed in a magnetic field B of 1.5 T. The magnetic field is perpendicular to the plane of the slab and to the current .The free electron concentration in copper is 8.4 × 1028 electrons/m3? . What will be the magnitude of the Hall voltage across the width of the slab?

Sodium has a body-centered cubic structure with a one-atom basis .The density and atomic weight of sodium are 0.971g/cm3 and 23 g/mole. What is the length of the unit cube of the structure?

A neutron spectroscopy a beam of mono energetic neutrons is obtained by reflecting reactor neutrons from a beryllium crystal. If separation between the atomic planes of the beryllium crystal is 0.732 A°, what is the angle between the incident neutron beam and the atomic planes that will yield a monochromatic beam of neutrons of wavelength 0.1 A°.

The energy gap in silicon is 1.1 eV, whereas in diamond it is 6eV. What conclusion can you draw about the transparency of the two materials to visible light(4000 A° to 7000 A°)?

Explain Bloch theorem? Discuss its use in the Kronig-Penny model and hence in band theory.

Assuming that atoms are in a crystal structure and arranged as close-packed spheres, what is the ratio of the volume of the atoms to the volume available for the simple cubic structure? Assume a one-atom basis.

Explain Hall Effect and discuss the impotence’s of hall voltage while manufacturing electronic devices.

A current of 50A is established in a slab of copper 0.5cm thick and 2 cm wide .The slab is placed in a magnetic field B of 1.5 T. The magnetic field is perpendicular to the plane of the slab and to the current .The free electron concentration in copper is 8.4 × 1028 electrons/m3? . What will be the magnitude of the gall voltage across the width of the slab?

Copper has a face -centered cubic structure with a one -atom basis .The density of copper is 8.96 g m c m − 3 and its atomic weight is 63.5 g/mole. What is the length of the unit .cube of the structure?