ELECTRONICS 1 QUIZ #1 REVIWER
1. Knee Voltage - voltage at which the forward diode current increases rapidly; germanium is 0.3V &
for silicon is 0.7V
2. Dipole - the physical arrangement of two opposite charges (positive and negative)
3. Recombination - merging of a free electron and a hole
4. Extrinsic - a doped semiconductor
Intrinsic - a pure semiconductor
5. Reverse Region - the voltage present across a diode
during reverse biasing does not produce any significant
flow of current. Furthermore, this particular
characteristic is beneficial for changing alternating
current (AC) into direct current (DC).
Forward Region - occurs when the voltage across a
diode permits the natural flow of current, whereas
reverse biasing denotes a voltage across the diode in
the opposite direction
Breakdown Region - the region where the collector
voltage is too large that the collector-base diode
breaks down, causing a large, undesired collector
current to flow
6. Positive Ion - a neutral atom that has lost one or more electrons
Negative Ion - a neutral atom that has gained one or more electrons
7. PIV (Peak Inverse Voltage) or PRV (Peak Reverse Voltage) - the maximum reverse-bias potential that
can be applied before entering the Zener region
8. Forward Bias - the battery pushes holes and free electrons toward the junction; if the battery voltage
is less than the barrier potential, the free electrons do not have enough energy to get through the
depletion layer
Reverse Bias - the negative battery terminal is connected to the p side and the positive battery
terminal to the n side; depletion layer widens the negative battery terminal attracts the holes, and
the positive battery terminal attracts the free electrons
No Bias - each dipole has an electric field between the positive and negative ions; if additional free
electrons enter the depletion layer, the electric field tries to push these electrons back into the n
region
9. Avalanche Breakdown - when a high reverse voltage is applied across the diode; as we increase
the applied reverse voltage, the electric field across the junction increases ( applied reverse
voltage,
 electric field across the junction)
Zener Breakdown - the breakdown of PN junction in a semiconductor diode which occurs due to the
flow of free electrons across the junction, occurs at low reverse voltage whereas avalanche
breakdown occurs at high reverse voltage
10. Valence Band - energy band formed from those energy levels of the atoms which contain the
valence electrons
Conduction Band - band of electron orbitals that electrons can jump up into from the valence band
when excited; when the electrons are in these orbitals, they have enough energy to move freely in
the material; this movement of electrons creates an electric current
11. Reverse Saturation Current - reverse current caused by the thermally produced minority carriers, the
current that exists under reverse-bias conditions, is represented by Is
Surface Leakage Current - a small current flow on the surface of the crystal, caused by surface
impurities and imperfections in the crystal structure, surface-leakage current is directly proportional
to the reverse voltage (surface-leakage current = reverse voltage)
Then you can see that the skin of a crystal is like a p-type semiconductor. Because of this, electrons can
enter the left end of the crystal, travel through the surface holes, and leave the right end of the crystal. In
this way, we get a small reverse current along the surface.
12. Ambient Temperature - the temperature of the air outside the diode, the air that surrounds the
diode,
Junction Temperature - temperature inside a diode, right at the pn junction
When the diode is conducting, the junction temperature is higher than the ambient temperature because
of the heat created by recombination. The barrier potential depends on the junction temperature. Now we
can state a rule for estimating the change in barrier potential: The barrier potential of a silicon diode
decreases by 2 mV for each degree Celsius rise.
13. Barrier Potential - the electric field between the ions is equivalent to a difference of potential
(electric field between the ions = difference of potential
14. Depletion Region or Depletion Layer – a charge-empty region, as the number of dipoles builds up,
the region near the junction is emptied of carriers
15. Lifetime - the amount of time between the creation and disappearance of a free electron
16. Valence Electron – electrons found in outermost shell or valence shell
17. Biasing - direct current (DC) deliberately made to flow, or DC voltage deliberately applied,
between two points for the purpose of controlling a circuit; to apply fixed dc voltage to an
electronic component (active component) like a transistor in order to establish proper operating
conditions for the component.
18. Semiconductor - a material that has a conductivity level somewhere between the extremes of an
insulator and a conductor, metalloids
Insulator - a material that offers a very low level of conductivity under pressure from an applied
voltage source, non-metals
Conductor - any material that will support a generous flow of charge when a voltage source of
limited magnitude is applied across its terminals, metals
19. P-type Material – Majority carriers are holes, minority carriers are electrons; created when
semiconductor materials are doped with trivalent atoms
N-type Material – Majority carriers are electrons, minority carriers are holes; semiconductor materials
are doped with pentavalent atoms
20. Trivalent - Boron, Aluminum, Gallium; acceptor atom; excess electrons
Pentavalent - Antimony, Arsenic, Phosphorous; donor atom; excess holes
21. 1st Approximation of a Diode - the diode is considered as a forward-biased diode and as a closed
switch with zero voltage drop, not apt to use in real-life circumstances but used only for general
approximations where preciseness is not required
2nd Approximation of a Diode - the diode is considered as a forward-biased diode in series with a
battery to turn on the device; For a silicon diode to turn on, it needs 0.7V. A voltage of 0.7V or
greater is fed to turn on the forward-biased diode. The diode turns off if the voltage is less than 0.7V
3rd Approximation of a Diode - is a switch in series with a barrier potential of 0.7 V and a resistance of
RB.; when the diode voltage is larger than 0.7 V, the diode conducts. During conduction, the total
voltage across the diode is: VD = 0.7 V + IDRB. Often, the bulk resistance is less than 1 Ω, and we can
safely ignore it in our calculations. A useful guideline for ignoring bulk resistance is this definition:
Ignore bulk: RB < 0.01RTH
22. Bulk Resistance - sum of the ohmic resistances of the diode, depends on the size of the p and n
regions and how heavily doped they are, less than 1Ω.
23. Power Rating of a Diode - power that a PN junction or diode can dissipate without damaging the
device itself or can safely dissipate
24. Diode Specification Sheet
 The forward voltage VF (at a specified current and temperature)
 The maximum forward current IF (at a specified temperature)
 The reverse saturation current I R (at a specified voltage and temperature)
 The reverse-voltage rating [PIV or PRV or V(BR), where BR comes from the term “breakdown”
(at a specified temperature)]
 The maximum power dissipation level at a particular temperature, P D
 Capacitance, CD
 Reverse recovery time, trr
 Operating temperature range
25. Maximum DC Forward Current of a Diode - the maximum value of the forward current that a PN
junction or diode can carry without damaging the device
26. Reverse Breakdown Voltage - the amount of reverse bias that will cause a p-n junction (diode) to
break down and conduct in the reverse direction, the reverse anode voltage at which the diode
conducts a specified amount of reverse current
27. Covalent Bond - sharing of electrons between atoms, occurs between two atoms of the same
element or of elements close to each other in the periodic table, occurs primarily between
nonmetals; however, it can also be observed between nonmetals and metals
Ionic Bond - atoms transfer electrons to each other, require at least one electron donor and one
electron acceptor, bond is typically between a metal and a non-metal
28. Transient Current - if there is inductor or capacitor in a circuit, the current will not become maximum
from zero or from maximum to zero in no time. The current will take a finite time or one can say it is a
gradual process. Thus, the electric current which takes finite time to become maximum from zero or
zero from maximum in circuits having inductors and capacitors (condensers), then such time of
currents
29. Ideal Diode - a switch that can conduct current in only one direction, a short circuit for the region of
conduction. RF = VF / IF = 0V / 1mA or any positive current, RF= 0Ω (short circuit), an open circuit in the
region of nonconduction. RR = VR /IR = -1 or any negative voltage/0 mA, RR = ꝏΩ(open-circuit)
Practical Diode - a two terminal devices, which allow most of the electric current under forward
bias, and block most of the electric current under reverse bias; can’t act as a perfect conductor
and perfect insulator
30. Characteristic Curve - a plot between voltage and current, where the horizontal axis is the voltage
while the vertical axis is the current
BASES FOR COMPARISON FOR CONDUCTOR, INSULATOR, AND SEMICONDUCTOR
CONDUCTOR
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The term conductor is applied to any material that will support a generous flow of charge when a
voltage source of limited magnitude is applied across its terminals.
Metals: Copper, aluminum, silver, gold, nickel, lithium, tin
Conductivity: Good conductor
Energy Band: No band gap. Conduction band and valence band overlap each other.
Temperature Coefficient: Positive temperature
Charge Carriers: Electrons.
Current Flow: Current flow due to electrons.
Number of Charge Carriers: Very High.
Valence Electron: 1
Effect of temperature on conductivity: Conductivity decreases. In metals, conductivity is due to the
movement of free electrons. When T increases, the vibration of metal ions increases. These vibrating
ions collide with the electrons. This results in the increase in R of metal and hence, resistivity increases
and conductivity decreases.
Bonding Types: Metallic and Ionic bond.
Behavior at Absolute 0K temperature (very low temperature): Behaves like superconductor
INSULATOR
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I - The elements which do not allow any flow of electric charge Dielectric, non-metals). An insulator
is a material that offers a very low level of conductivity under pressure from an applied voltage
source
Non-Metals: Wood, Rubber, Glass (SiO2), Mylar, Mica
Conductivity: Poor conductor
Energy Band: Large band gap. Conduction band and valence band are separated by >5eV.
Temperature Coefficient: Negative Temperature
Charge Carriers: They do not contain any charge carriers.
Current Flow: Current does not flow.
Number of Charge Carriers: Negligible. (Almost zero)
Valence Electron: 8
Effect of temperature on conductivity: Conductivity increases. The resistance will decrease with
increasing temperature, mainly due to the large energy gap.
Bonding Types: Ionic Bond and Covalent Bond.
Behavior at Absolute 0K temperature (very low temperature): Behaves like an Insulator
SEMICONDUCTOR
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S - The elements whose conductivity lies between insulators and conductors, metalloids. A
semiconductor, therefore, is a material that has a conductivity level somewhere between the
extremes of an insulator and a conductor
Metalloids: Germanium, Silicon
Conductivity: Intermediate. Pure semiconductor material (intrinsic) acts as insulator, becomes good
conductor when added with impurities (extrinsic).
Energy Band: Small Band gap. Conduction band and valence band separated by 1.1eV (Si), 0.67V
(Ge) and 1.41eV (GaAs), GaAs does have a considerably higher bandgap than silicon does and
has an indirect band gap.
Temperature Coefficient: Negative Temperature
Charge Carriers: Intrinsic charge carriers are holes and electrons.
Current Flow: Current flow due to holes and electrons.
Number of Charge Carriers: Low.
Valence Electron: 4
Effect of temperature on conductivity: Conductivity increases. An increase in temperature of a
semiconductor can result in a substantial increase in the number of free electrons in the material. As
the temperature rises from absolute zero (0 K), an increasing number of valence electrons absorb
sufficient thermal energy to break the covalent bond and contribute to the number of free carriers
as described above. This increased number of carriers will increase the conductivity
Bonding Types: Covalent Bond
Behavior at Absolute 0K temperature (very low temperature): Behaves like an Insulator.