Define absorption, spontaneous emission and stimulated emission for bulk semiconductors.
[3 marks]Write a short note on P-Njunction diode.
[4 marks]Give assumptions of classical free electron theory and discuss its limitations.
[7 marks]Find the temperature at which there is 1% probability that a state with energy 2eV is occupied. Given that Fermi energy is 1.5 eV.
[3 marks]What is drift and diffusion current in p-n junction diode?
[4 marks]Explain the Kronig-Penny model of solids and show that how it explains the origin of band gap in solids.
[7 marks]Explain intrinsic and extrinsic (N & Ptype) semiconductors with the help of energy band diagram.
[7 marks]In an N-type semiconductor, the Fermi level lies 0.3 eV below the conduction band at room temperature. If the temperature is increased to 330K, Find the position of Fermi level.
[3 marks]Write an expression for Fermi Dirac distribution function f(E). Show that at all temperatures (T > 0K) probability of occupancy of Fermi level is 50%.
[4 marks]Discuss the effect of temperature on the Fermi level in extrinsic (N & P type) semiconductors.
[7 marks]Find the concentration of holes and electrons in N-type silicon if the conductivity is 0.1 -cm-1, mobility of electrons is 1300 cm2/V-s and total carrier concentration is 1.5x1010 carriers / cm3.
[3 marks]Establish the relation between Einstein’s coefficients.
[4 marks]Explain Meissener’s effect in detail and show that for superconductor, χ = –1. m
[7 marks]Write a short note on effective mass of electron.
[3 marks]What is mass action law? Explain Schottky junction.
[4 marks]Explain Drude model and discuss how it is used for Hall measurements and magnetoresistance.
[7 marks]What is an exciton? What is DLTS? Define Hall mobility.1
[3 marks]What is Fermi level and Fermi energy? What is Photovoltaic Cell?
[4 marks]Explain four point probe method with diagram for the measurement of resistivity of bulk sample.
[7 marks]Explain Fermi Golden rule for transition probability.
[3 marks]What is Josephson junction? Write a short note on SQUID.
[4 marks]Explain how to measure band gap of the semiconductor using UV-Vis spectroscopy.
[7 marks]Calculate the critical current for a superconducting wire of lead having a diameter of 1mm at 4.2 K. Critical temperature for lead is 7.18 Kand H (0) = 6.5 x 104A/m. c
[3 marks]Write a short note on Hot-point probe measurement technique.
[4 marks]What is superconductivity? Explain any six properties of superconductor.
[7 marks]