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PN-Diode Test
Version 1
The purpose of this test is to verify your understanding of the PN - diode. Please
respond to all the questions.
What is your nanoHUB account?
A semiconductor is characterized by the idealized energy-band diagram shown in the
figure below.
In which of the figures below the potential and the electric field profile are sketched as a
function of x?
PN-Diode Test
Version 1
none of the above
Considering the previous figure, what is the magnitude of the electron drift current
density at x = xa?
Negative
Positive
Zero
Considering the previous figure, is there any electron diffusion current at x = xb?
Yes
No
If there is diffusion current at x=xb, what is the direction of the current?
From left to right.
From right to left.
If there is diffusion current, what is the magnitude of the total current at x = xb?
Positive.
Negative.
Zero.
In an ideal diode model it is assumed that:
there is generation-recombination in the depletion region
there isn’t generation-recombination in the depletion region
PN-Diode Test
Version 1
none of the above
In a diode operated under forward bias conditions:
generation effect dominates
recombination effect dominates
none of the above
In a diode with NA > ND, the width of the depletion regions at the p- and n-side are such
that:
Wp > Wn
Wp < Wn
Wp = Wn
If the doping of the p-side (NA) doubles, the width of the depletion region in the p-side
Increases
Decreases
Stays the same
If the doping of the p-side (NA) doubles, the peak electric field at the metallurgical
junction:
Increases
Decreases
Stays the same
When is the width of the total depletion region of a diode larger?
Under forward bias conditions
Under reverse bias conditions
none of the above
When is the peak electric field value at the metallurgical junction larger?
Under forward bias conditions
Under reverse bias conditions
PN-Diode Test
Version 1
none of the above
When does high level injection dominate?
Reverse bias
Small forward bias
Large forward bias
When does series resistance effect in a diode become important?
Reverse bias
Small forward bias
Large forward bias
In a p+-n junction, the n-doping ND is doubled. How does the junction
capacitance changes if everything else remains unchanged?
increases
decreases
stays the same
In a p+-n junction, the n-doping ND is doubled. How does the built-in potential changes
if everything else remains unchanged?
increases
decreases
stays the same
In a p+-n junction, the n-doping ND is doubled. How does the breakdown voltage
changes if everything else remains unchanged?
increases
decreases
stays the same
In a p+-n junction, the n-doping ND is doubled. How does the Ohmic losses change if
everything else remains unchanged?
PN-Diode Test
Version 1
increase
decrease
stay the same
Consider the following figure:
From the options below, which one sketches a qualitative energy band diagram and
electric-field profile in thermal equilibrium for an-i-p-i-n structure where the p-layer in the
middle is very thin and the concentration of acceptors in the p-type layer, NA, is
relatively small?
PN-Diode Test
Version 1
none of the above
Considering a qualitative energy band diagram and electric-field profile in thermal
equilibrium for a n-i-p-i-n structure where the p-layer in the middle is very thin and the
concentration of acceptors in the p-type layer, NA, is relatively small. The dielectric
permittivity of the semiconductor is epsilon.
What is the profile of the electric field in the i-regions under reverse bias conditions?
Constant.
Spatially varying.
None of the above.