Semiconductors Flashcards
(25 cards)
At very high temperatures the extrinsic semiconductors become intrinsic because…
A. drive in diffusion of dopants and carriers
B. band to band transition is dominant over impurity ionization
C. impurity ionization is dominant over band to band transition
D. band to band transition is balanced by impurity ionization
band to band transition
is dominant 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 the positive terminal
A diode is a
A. unidirectional device.
B. linear device
C. nonlinear device
Both A and C
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?
A. Selenium
B. Silicon
C. Copper
D. Germanium
Germanium
A semiconductor, such as silicon, has an electron valence of…
±4
Assertion (A): The reverse saturation current in a semiconductor diode is 4nA at 20°C and 32nA at 50°C.
Reason (R): The reverse saturation current in a semiconductor diode doubles for every 10°C rise in temperature.
A. Both A and R are true and R is
correct explanation of A
B. Both A and R are true but R is not
a correct explanation of A
C. A is true but R is false
D. A is false but R is true
Both A and R are true and R is
correct explanation of A
A disadvantage of gallium-arsenide devices is that
A. The charge carriers move fast
B. The material does not react to ionizing radiation.
C. It is expensive to produce
D. It must be used at high frequencies
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…
A. the type of semiconductor material
B. the cross-sectional area of the junction
C. the reverse current
D. the capacitance with reverse bias
the reverse current
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.
A. Both A and R are true and R is
correct explanation of A
B. Both A and R are true but R is not
a correct explanation of A
C. A is true but R is false
D. A is false but R is true
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…
A. The junction will be destroyed
B. The junction will insulate; no current will flow
C. The junction will conduct current
D. The capacitance will become extremely high
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…
A. is negative relative to the cathode
B. is positive relative to the cathode
C. is at the same voltage as the cathode
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…
A. minimize the diode capacitance
B. optimize the avalanche voltage
C. reduce the forward break over voltage
D. increase the current through the
diode
minimize the diode capacitance
To a first approximation, a forward-biased diode is treated like a…
closed switch with no voltage drop.
The capacitance of a varactor varies with…
reverse voltage
A photodiode, when not used as a photovoltaic cell, has…
A. reverse bias
B. no bias
C. forward bias
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?
A. The material becomes p-type
B. Current flows mainly in the form of holes
C. Most of the carriers have positive electric charge
D. The substance has an electron surplus
The substance has an electron surplus
