Review exam:ELEC04: Electronic Devices & Circuits 1 Flashcards
For a PN-junction we generally have
I. Width of depletion layer
Il. Junction barrier voltage
IlI. Reverse leakage current
Which of the above parameters will decrease when the temperature of the junction rises?
I and II only
At absolute zero temperature a semi-conductor behaves as:
Insulator
In a semiconductor avalanche breakdown takes place:
Reverse bias exceeds the limiting value
Before doping the semiconductor material is generally
Purified
What is considered the maximum forward current for silicon diode rectifier?
600 A
An electron in the conduction band:
Has higher energy than the electron in the valence band
What is considered the maximum peak inverse voltage for silicon diode rectifier?
1000V
An electron in the conduction band:
Has higher energy than the electron in the valence band
What is considered the maximum peak inverse voltage for silicon diode recrifier?
1000V
The ayomic mass unit in grams is the reciprocal of
Avogadro’s number
The ayomic mass unit in grams is the reciprocal of
Avogadro’s number
At room temperature when a voltage is applied to an intrinsic semi conductor
Electron move towards positive terminal and holes towards negative terminal
Which of the following decays decreases the number of both protons and neutrons by two and may result in a stable nucleus?
Alpha Decay
Majority carriers in an n-type semiconductor are
Electrons
Majority carriers in an n-type semiconductor are
Electrons
Calculate the maximum fraction of the volume in a simple cubic crystal occupied by the atoms. Assume that the atoms are closely packed and that they can be treated as hard spheres. This fraction is also called the packing density.
52%
(Volume ka sphere with radius (a/2) over volume ka cube (a^3)
What is the other name of negative electron
Negatron
In the reverse-bias region the saturation current of a silicon diode is about 0.1uA(T=20degrees). Determine its approximate value if the temperature is increased 40 degrees.
1.6uA
In case a PN junction is forward biased
Depletion region decreases
Which of the following is the first postulate of Niels Bohr to support his atomic structure theory?
Electron orbits are discrete non-radiating and the electron may not remain between these orbits
In a diode, the region near the junction consisting of positive and negative ions is called the
Depletion region
Calculate the effective densities of states in the conduction band or germanium at 300 degree K.
1.02x10^25 m^-3
What crystalline structure has a coordination number of 12?
Face centered cubic
Given Pmax=14mW for each diode, determine the maximum current rating of each diode (using the approximate equivalent model)
20mA
=14mW/0.7
Determine the diode current at 20 degrees C for a silicon diode with Is=0.1uA at a reverse-bias potential of -10V.
0.1uA
Shockley equation
The two types of current in a semiconductor are
Electron current and the whole current
Determine the temperature coefficient of a 5V zener diode(rated 25degrees C) if the nominal voltage drops to 4.8V at a temp of 100 degrees C.
0.053%/degrees C
A conductor material has a free electron density if 10^24 electrons per cubic meter. When a voltage is applied a constabt drift velocity of 1.5x10^-2 m/s is attained by the electrons. If the cross sectional area of the material is 1 cm^3 , calculate the magnitude of the current. Electron charge is 1.5x10^-19
0.24A
EG for silicon is 1.12 eV and for germanium is 0.73eV thus it can be concluded that
Less number of electron whole pairs will be generated in silicon than in germanium at room temperature
