Semicon Flashcards
At very high temperatures the
extrinsic semiconductors become
intrinsic because
band to band transition dominants
over impurity ionization
To forward-bias a diode
the anode voltage must be
positive with respect to its
cathode.
When a voltage is applied to a
semiconductor crystal then the free
electrons will flow.
towards positive terminal
A diode is a
unidirectional device.
linear device
Avalanche voltage is routinely
exceeded when a P-N junction acts as
a:
Voltage regulator
Of the following, which material
allows the lowest forward voltage
drop in a diode?
Germanium
A semiconductor, such as silicon, has
an electron valence of
±4.
Assertion (A): The reverse saturation
current in a semiconductor diode is 4
nA at 20°C and 32 nA at 50°C.
Reason (R): The reverse saturation
current in a semiconductor diode
doubles for every 10°C rise in
temperature.
Both A and R are true and R is
correct explanation of A
Determine the diode current at 20 ºC
for a silicon diode with reverse
saturation current of 50 nA and an
applied forward bias of 0.6 V
7.19 mA
A disadvantage of gallium-arsenide
devices is that:
It is expensive to produce
At room temperature the current in
an intrinsic semiconductor is due to
holes and electrons
An unimportant factor concerning
the frequency at which a P-N
junction will work effectively is:
The cross-sectional area of the
junction
Assertion (A): The conductivity of p
type semiconductor is higher than
that of intrinsic semiconductor.
Reason (R): The addition of donor
impurity creates additional energy
levels below conduction band.
Both A and R are true but R is not
a correct explanation of A
If the reverse bias exceeds the
avalanche voltage in a P-N
junction:
The junction will conduct current
When a P-N junction does not
conduct, it is:
Reverse biased
When a diode is forward-biased, the
anode:
Is positive relative to the cathode
The sharing of valence electrons in a
silicon crystal is called
covalent bonding.
The purpose of the I layer in a PIN
diode is to:
Minimize the diode capacitance
When a silicon diode is conducting at
a temperature of 27 ºC, reverse
saturation current is 35 nA, what is
the new reverse current at 50C?
175 nA
To a first approximation, a forwardbiased diode is treated like a (n)
closed switch with a voltage drop
of 0 V
The capacitance of a varactor varies
with:
Reverse voltage
A photodiode, when not used as a
photovoltaic cell, has:
. Reverse bias
Zener voltage is also known as:
Avalanche voltage
An n-type semiconductor is a
semiconductor that has been doped
with
pentavalent impurity atoms.
The purpose of doping is to:
Give a semiconductor material
certain properties
Which of the following does not
result from adding an
acceptor impurity?
The substance has an electron
surplus
A pure semiconductor is often
referred to as a (n)
intrinsic semiconductor
If ac is applied to a diode, and the
peak ac voltage never exceeds the
avalanche voltage, then the output is:
When a P-N junction is reversebiased, the capacitance depends on
all of the following except:
The frequency
If an electron has a charge of -1 unit,
a hole has:
A charge of +1 unit
Holes flow the opposite way from
electrons because:
Charge carriers are passed from
atom to atom
In an n-type semiconductor, the
minority current carriers are
holes.
When used as a voltage regulator, a
zener diode is normally
reverse-biased.
The most commonly used
semiconductor material is
silicon
A crystal set:
Requires no battery
The forward break over voltage of a
silicon diode is:
About 0.6 V or 0,7 V
Which of the following is not an
advantage of semiconductor devices
over vacuum tubes?
Ability to withstand high
voltages.
. A neutral atom with an atomic
number of three has how many
electrons?
3
Which of these diode types might be
found in the oscillator circuit of a
microwave radio transmitter?
An IMPATT diode
A p-type semiconductor is a
semiconductor doped with
trivalent impurity atoms.
A diode detector:
. Is employed in some radio
receivers
Selenium works especially well in:
Photocells
A semiconductor material is made
into N type by:
Adding a donor impurity
The charge on a single electron is
1.6 x 10-19 C
Holes flow from:
Plus to minus
A diode audio limiter circuit:
Can cause objectionable signal
distortion
In a p-type semiconductor, the
majority current carriers are
holes.
A diode audio limiter circuit:
Can cause objectionable signal
distortion
Determine the temperature
coefficient of a 5 V zener diode
(rated 25˚C value) if the nominal
voltage drops to 4.8 V at a
temperature of 100˚C.
0.053 %/˚C
The term “semiconductor” arises
from:
The term “semiconductor” arises
from:
