a) What do you mean by Fermi level? By indicating the position of Fermi level in intrinsic, n-type and p- type semiconductor, describe its significance in semiconductors?
b) Sketch V-I characteristics of a PN diode for the given conditions:
i) Rf = 0, Vγ = 0, Rr = ∞
ii) Rf = 0, Vγ= 0.6V, Rr = ∞
iii) Rf = Non-zero, fixed value, Vγ = 0, Rr = ∞
iv) Rf = Non-zero, fixed value, Vγ = 0. 6V, Rr = ∞
Where Vγ is the cut-in voltage, Rf is the forward dynamic resistance & Rr is the reverse dynamic resistance of the diode.
a) What do you understand about the depletion region at a PN junction, with the help of essential diagrams and derive expression for barrier potential.
b) Derive the expression for transition capacitance, CT of a PN diode.
a) With the help of necessary sketches describe the potential distribution in an open circuited PN junction.
b) With the help of V-I Characteristics, describe the operation of a PN Diode under Forward bias and Reverse bias.
a) Describe Avalanche and Zener break down mechanisms in semiconductors and also compare them?
b) For Zener diode circuit shown in figure below, find out VL, VR, IZ & R.
a) Describe the V-I characteristics of Zener diode and distinguish between Avalanche and Zener Break downs.
b) In a Zener diode regulator, the supply voltage = 300V, Vz = 220V, Iz = 15mA and load current = 25mA. Compute the value of resistor required to be connected in series with the Zener diode.
a) Describe the effect of temperature on V-I characteristics of a diode.
b) Differentiate between drift and diffusion current in a semiconductor. Illustrate continuity equation.