The smallest particle of an element that possesses the characteristics of that element
Barrier potential
the amount of energy required to produce full conduction across the PN junction in forward bias
Bias
The application of a DC voltage to a diode to make it either conduct or block current
Cathode
The N region of the diode which is negative
Crystal
A solid material in which the atom are arranged in a symmetrical pattern
Diode
A semiconductor device with a single PN junction that conducts current in only one direction.
Doping
The process of imparting impurities to an intrinsic (pure) semiconductive material in order to control its conduction characteristics
Forward Bias
The condition in which a diode conducts current
Free Electron
An electron that has aquired enough energy to break away from the valence band of the parent atom
Hole
The absence of an electron in the valence band of an atom
Ionization (positive ion, negative ion)
The removal or addition of an electron from or to a nuetral atom so that the resulting atom has a positive or negative charge.
PN junction
The boundry between two different types of semiconductive materials
Reverse Bias
The condition in which a diode prevents current. ( action like an open switch)
Semiconductor material
Silicon, Germanium and carbon
V-I characteristic
A curve showing the relationship of a diode voltage and current
N-type impurity atom
Pentavalent atoms which have five valence electrons
P-type impurity atom
Trivalent atoms which have three valence electrons
Covalent bond
is created by the sharing of valence electrons
Electron current
When a voltage is applied across the semiconductor the free electrons move towars the the positive end (to the right)and form the current
Hole current
This occurs as valence electrons move from hole to hole (left to right)creating a movement of holes from right to left
The majority carriers in N-type semiconductors
free electrons
The minority carriers in N-type semiconductors
holes
The majority carriers in P-type semiconductors
holes
The minority carriers in P-type semiconductors
free electrons
How a PN junction is formed
when part of a material is doped N-type and part is doped P-type. A depletion region forms by ionization and starts at the junction that is devoid of any majority carriers
The barrier potential for a silicon diode
0.7V
The barrier potential for a germanium diode
0.3V
What does the dig. multimeter display when the diode is in reverse bias but working properly?
OL
What does the dig. multimeter display when the diode is working in forward bias?
0.7V or 0.3V
Reverse breakdown voltage for a diode
greater than 50V
What does the dig. multimeter display when the diode is open?
OL in forward and reverse bias
What does the dig. multimeter display when the diode is shorted?
0V in forward and reverse bias
IF= forward current for ideal diode model
IF= VBias......RLimit
IF= Forward current for practical diode model
IF= Vbias-VF ..........RLimit
The ideal diode model
Used for troubleshooting and does not give exact voltage or current. It is represented as a switch. Forward bias =closed switch. Reverse bias= open switch.
The practical diode model
includes barrier potentail which is written as VF = 0.7V. VBias is the Voltage that is applied to the circuit