solid state electronics
mean life time of carrier
The amount of time between creation and disappearance of a free electron or hole is called __________
zero; non zero
The average value of the input sine wave is ______ but when applied to a rectifier it converts it into a ________ average component
rectification.
The process of converting AC to DC is called _______
2; 8; 4
silicon has ____ electrons in the first orbit, ____ electrons in the second, ____ electrons in the outer valence orbit.
14
silicon has atomic number of ____, meaning that it has ____ protons and ____ electrons
N-type; P-type
■ Depending upon the type of impurity added, extrinsic semiconductors are classified in two types namely _______semiconductor and _______ semiconductor.
capacitor
○ A _______ passes AC easily but does not allow DC.
intrinsic semiconductor
○ A semiconductor in an extremely pure form is known as an _______
rectification.
○ One of the most important application of diode is ________
zener breakdown voltage
○ The zener should be selected in such a way that the required regulated output voltage V0 should be equal to ______.
batteries
● Almost all electronic circuits require a DC source of power, but for portable low power systems, _______ may be used.
NPN transistor
● Consider a silicon or germanium crystal in which a layer of P-type silicon is sandwiched between two layers of N-type silicon. Such a type of transistor is called __________
rectifier and the load
● Filter should be installed between the _______ and _______
diode.
A piece of component which converts a sinusoidal AC waveform into single polarity half cycles is _____
2; 8; 18; 4
According to equation N = 2n2 , Germanium has only _____ electrons in first orbit, __ electrons in the second, -___ electrons in the third and only _____ electrons in the outer valence orbit.
P-side; N-side
After diffusion, negative ions are formed on the ______ and positive ions are formed on the ______ closer to the junction.
1 part in 10 million
Generally to an extent not greater than _________ is added to a pure semiconductor, then it is called impurity or extrinsic semiconductor
applied to N-type
When external voltage V is __________semiconductor, the free electrons available in the semiconductor gain sufficient energy, breaks the bond and move in a direction towards positive terminal of battery. But the holes are less in number
hole current.
Since electrons are very less they move from negative terminal of V to positive terminal, but conventional direction of current is the direction of the _______
32
Since germanium has an atomic number of ___ meaning that it has ____ protons and ___ electrons
release of energy in the form of heat.
Such a recombination in semiconductors results in ___________ This amount of energy released as heat is equal to the energy required to break covalent bond.
1.Capacitor 2.Inductor 3.LC-filter or L-section or choke input filter 4.CLC filter or p-section of capacitor input filter
TYPES OF FILTER
junction transistor
The ________ is a three layer and three terminal semiconductor device,
equal number; covalent bond
While formation of covalent bonds, every atom in the semiconductor contribute ________ of valence electrons and hence these contributed electrons are shared by the atoms engaged in the formation of the ________
Capacitor Filter
______ is commonly used because of its low cost, small in size and negligible weight.
Transistor
_________ has now become the heart of most electronic applications and is increasingly used in all applications in the fast developing electronics industry.
'ISTOR'
__________ classifies it as a solid state element in the family of resistors.
filter
a device, which removes AC component of the rectifier output but allows the DC component to reach the load or it is a circuit, which converts pulsating output of the rectifier into a steady DC level
N-Type: In N-type,
current conduction is due to electrons, hence electrons are majority carriers and holes are minority carriers. Since a donor impurity donates an electron it becomes positive ion
drift current; drift velocity
drift towards positive terminal of supply. The current that is produced due to drifting of these free electrons is called =
power supply.
electronic equipment is energized by a ________
● P-Type
n P-type semiconductor, current conduction is due to excess holes, hence holes are majority carriers and electrons are minority carriers. Since an acceptor impurity has accepted an electron, it becomes negative ion.
Inductor
opposes AC but allows DC to pass through it
semiconductor
substance whose electrical properties lies between conductors and insulators.
diffusion current
tendency that the charge carriers move from higher density to lower density and this process is referred as ______
very small
the energy required to break covalent bonds and to release electrons from the valence band is ______
1μ sec to 1 millisecond.
the life time of either hole or electron is limited to ___________
having incomplete electrons
this makes the atom active in extracting electrons from other atoms.
emitter, collector, base
three regions of transistor
transistor
transfers a signal from a low resistance to high resistance.
true
true or false: covalent bonded ions cannot move around like free electrons and holes.
1.Half wave rectifier 2.Full wave rectifier
types of rectifier
N-side; donor atom; positively charged immobile ion
y when a hole diffuses into ____ they recombine with ________, this donor atom accepts additional hole and they become _________ and the electron disappears.
vacancy
○ When a valence electron drifts from valence to conduction band breaking a covalent bond, a _______ is created in valence band (orbit).
Filter circuit
○ ________ is used between rectifier output and load in order to remove AC component so that only the DC component passes to the load.
depletion region or space charge region
● In between, these immobile charges at the junction there exists no charge carriers such a region is called _______
Transistor; William Shockley in 1947
● _________ is one of the most important semiconductor devices invented by _________ in ______
alloying
n the temperature is lowered to form a single slab after solidification
tetravalent; 4
Both silicon and germanium are ______, having only _____ valence electrons in each atom which enters into covalent bond formation with the neighboring atoms.
zener diode
A _______ can be used as a voltage regulator, since it maintains a constant output voltage even though the current through the zener changes.
junction transistor; transistor.
A _______ is simply a sandwich of one type of semiconductor material (p- type or n-type) between two layers of opposite type, the resulting device is known as a________
inductors (L) and capacitors (C).
A filter circuit is generally a combination of ______ and ______
PNP transistor.
A junction transistor consists of a silicon (or germanium) crystal in which a layer of Ntype silicon is sandwiched between two layers of P-type silicon called ______
electron-hole pair
Whenever an electron becomes free, the corresponding hole gets generated, creating what is called __________
DONOR
Each pentavalent impurity atom is added to intrinsic semiconductor contributes or donates one free electron and is therefore referred to as _____
P-N junction
P-N junction is formed when a single crystal of semiconductor is added with acceptor impurity on one side and donor impurity on the other side
N-type
PNP transistor composed of two p-type semiconductors separated by a thin layer of __________
a. have crystalline structure. b. The resistivity is less than insulator, but more than conductor. c. With increase in temperature the resistivity decreases, hence conductivity increases. d. When a suitable impurity is added like gallium, arsenic, antimony, etc the properties change appreciably towards conductor. e. perfect insulator at low temperature but perfect conductor at very high temperature
Properties of Semiconductors:
room temperature
An intrinsic semiconductor at ________ absorbs heat energy from the surrounding
break up; valence band to conduction band
An intrinsic semiconductor at room temperature absorbs heat energy from the surrounding that causes some of the covalent bonds to ______ and causes some electrons to jump from __________ to ________
low resistance; rectifier.
Any electrical device used for rectification offers a _________ to the current in one direction but a very high resistance to the current in the opposite direction is called __________
same; large positive; negative; further migration
If the doping density is ______ for both semiconductor blocks, then _____charge gets accumulated on N-side and large ______charge gets accumulated on P-side near the junction, thus these charges at junction repel and doesn't allow _______ of carriers from one side to the other.
filled and stable.
If the outermost shell contains eight electrons then it is said to be completely _____ and ____
diffusion
In P-type excess holes move towards P-side similarly electrons from N-side move towards P-side, this process is called _____ and diffusion of charge carriers take place on either side.
equal to the number of holes
In an intrinsic semiconductor, the number of free electrons will be ________.
extracting electrons from other atoms
In doing so the atom may gain electrons or loose electrons with other atoms forming covalent bonds.
rate of recombination; free electrons and holes; equal
The __________ is proportional to the densities of _________ if the temperature increases then the densities of electrons and holes increase, until the resulting increased rate of recombination ______ to the increased rate of production
free electrons
The dislodged electrons in semiconductors are called ________ and are free to drift
crystalline in structure
The examples for intrinsic semiconductors are germanium and silicon, but both these materials are ________
Ntype semiconductor or negative type semiconductor
The impurity semiconductor containing donor atoms is called _________
germanium and silicon
The most widely used semiconductor materials are
pulsating
The output of a rectifier is _______
'TRANS'
The prefix _______ means the signal transfer property of the device
doping
The process of adding impurities to a pure semiconductor is known as ________
flows through the load.
The rectifiers are classified according to the period of time the current __________
"Transfer Resistor".
The term transistor is derived from ________
0.150; 0.001
The total width of the transistor is about _____inch and width of base is _______ inch and all the three portions are grown out of the same crystal by adding corresponding impurities
vanish
These holes and electrons in a semiconnductor move randomly within the crystal lattice when one such free electron meets a hole, they recombine to establish the covalent bond in a semiconductor, so both the electron and hole then _____.
bonding action of valence electrons
This bonding is due to the fact that it is the tendency of each atom of every element to complete its last orbit by extracting eight electrons into it
hole.
This vacancy of an electron is called _______
gain sufficient energy and break
When external voltage V is applied to P-type, the free holes available in semiconductor gain sufficient energy and break the covalent bonds and move in a direction towards negative terminal of V.
DRIFT CURRENT
When external voltage is applied to a semiconductor, the free electrons in the semiconductor gain sufficient energy and travels towards positive terminal of supply
Ptype; acceptor atoms; negatively charged immobile ion; valence electron.
When the migrating electron diffuse into ____and recombines with the _______ on P-side, the acceptor ion accepts this additional electron and becomes ________, and the hole disappears and free electron becomes a ______
N-type semiconductor
When a small amount of penta-valent impurity (having 5 valence electrons) is added to a pure semiconductor, the resulting semiconductor is known as ___________
P-type semiconductor
When a small amount of trivalent impurity (having 3 valence electrons) is added to a ________ the resulting semiconductor is known as
P-type semiconductor
When a small amount of trivalent impurity is added to a pure semiconductor the resulting semiconductor is known as p-type semiconductor.
thermal generation; random
When electrons and holes are generated due to _______, they move in ______ motion but cannot constitute any current in the device.
NPN transistor.
a transistor may consist of a layer of P-type silicon sandwiched between two layers of N-type silicon called __________
the bonding action of valence electrons
all the atoms of every element are held together due to?
NPN transistor
an_______ is composed of two N-type semiconductors separated by a thin layer of p-type
large number of electron-hole pairs
as the temperature is increased beyond the room temperature of an intrinsic semiconductor then ___________ are created.
intrinsic semiconductor
behaves as perfect insulators at absolute zero temperature
0.785eV
energy required to break covalent bonds and to release electrons from the valence band in germanium
1.2eV
energy required to break covalent bonds and to release electrons from the valence band in siliccon
Germanium, Silicon, Selenium, Gallium arsenide, Lead sulphide, etc
examples of semiconductors
108; one; light doping
for every _______ atoms of semiconductor, only ____ impurity atom is added. This type of doping is called _______
rectification.
he most important application of semiconductor diode.
Emitter
heavily doped, so that it can emit or inject large number of majority carriers from the emitter terminal into the device
steady drift; opposite
if an electric field is applied across the crystal, there is a ________ of these free electrons ________ to the direction of electric field, constituting electric current through the device.
8
most of the substances in which the last orbit is incomplete having less than ______ electrons.
