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Electronics > Semiconductors > Flashcards

Semiconductors Flashcards

1
Q

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

A

band to band transition
is dominant over impurity
ionization

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2
Q

To forward-bias a diode…

A

the anode voltage must be
positive with respect to its
cathode

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3
Q

When a voltage is applied to a semiconductor crystal then the free electrons will flow…

A

towards the positive terminal

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4
Q

A diode is a
A. unidirectional device.
B. linear device
C. nonlinear device

A

Both A and C

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5
Q

Avalanche voltage is routinely exceeded when a P-N junction acts as a…

A

voltage regulator

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6
Q

Of the following, which material allows the lowest forward voltage drop in a diode?
A. Selenium
B. Silicon
C. Copper
D. Germanium

A

Germanium

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7
Q

A semiconductor, such as silicon, has an electron valence of…

A

±4

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8
Q

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

A

Both A and R are true and R is
correct explanation of A

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9
Q

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

A

It is expensive to produce

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10
Q

At room temperature, the current in an intrinsic semiconductor is due to…

A

holes and electrons

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11
Q

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

A

the reverse current

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12
Q

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

A

Both A and R are true but R is not a correct explanation of A

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13
Q

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

A

the junction will conduct current

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14
Q

When a P-N junction does not conduct, it is…

A

reverse biased

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15
Q

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

A

is positive relative to the cathode

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16
Q

The sharing of valence electrons in a silicon crystal is called

A

covalent bonding

17
Q

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

A

minimize the diode capacitance

18
Q

To a first approximation, a forward-biased diode is treated like a…

A

closed switch with no voltage drop.

19
Q

The capacitance of a varactor varies with…

A

reverse voltage

20
Q

A photodiode, when not used as a photovoltaic cell, has…

A. reverse bias
B. no bias
C. forward bias

A

reverse bias

21
Q

Zener voltage is also known as…

A

avalanche voltage

22
Q

An n-type semiconductor is a semiconductor that has been doped with…

A

pentavalent impurity atoms

23
Q

The purpose of doping is to…

A

give a semiconductor material
certain properties

24
Q

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

A

The substance has an electron surplus

25
Q
A

Electronics (1 decks)

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