Electronics and Communication Engineering
GATE ECE Carrier transport PYQs
Build your understanding with focused practice from past exam papers.
Questions 11–17 of 17. Imported answers require independent review unless marked reviewed.
Question 10
Open questionECMCQ1 markNeeds review
A
-
Silicon device is fabricated with uniform and non-degenerate donor doping concentrations of
and
corresponding to the
and
regions respectively. At the operational temperature
, assume complete impurity ionization,
, and intrinsic carrier concentration to be
. What is the magnitude of the built-in potential of this device?Your answerChoose one option.
Log in to check the answer
You can attempt this question now. Sign in to view the answer key, explanations and discussion.Log in to check answerQuestion 11
Open questionECMCQ1 markNeeds review
For a narrow base PNP BJT, the excess minority carrier concentrations (
for emitter,
for base,
for collector) normalized to equilibrium minority carrier concentrations (
for emitter,
for base,
for collector) in the quasi-neutral emitter, base and collector regions are shown below. Which one of the following biasing modes is the transistor operating in? 
X and Y axes are not to scale
Your answerChoose one option.
Log in to check the answer
You can attempt this question now. Sign in to view the answer key, explanations and discussion.Log in to check answerQuestion 36
Open questionECNAT2 marksNeeds review
The dependence of drift velocity of electrons on electric field in a semiconductor is shown below. The semiconductor has a uniform electron concentration of
and electronic charge
. If a bias of 5 V is applied across a 1
m region of this semiconductor, the resulting current density in this region, in kA/cm
, is __________.
Log in to check the answer
You can attempt this question now. Sign in to view the answer key, explanations and discussion.Log in to check answerQuestion 37
Open questionECNAT2 marksNeeds review
As shown, a uniformly doped Silicon (Si) bar of length
with a donor concentration
is illuminated at
such that electron and hole pairs are generated at the rate of
,
, where
. Hole lifetime is
s, electronic charge
, hole diffusion coefficient
and low level injection condition prevails. Assuming a linearly decaying steady state excess hole concentration that goes to 0 at
, the magnitude of the diffusion current density at
, in A/cm
, is __________.
Log in to check the answer
You can attempt this question now. Sign in to view the answer key, explanations and discussion.Log in to check answerQuestion 38
Open questionECNAT2 marksNeeds review
As shown, two Silicon (Si) abrupt
-
junction diodes are fabricated with uniform donor doping concentrations of
and
in the
-regions of the diodes, and uniform acceptor doping concentrations of
and
in the
-regions of the diodes, respectively. Assuming that the reverse bias voltage is
built-in potentials of the diodes, the ratio
of their reverse bias capacitances for the same applied reverse bias, is ________. 
Log in to check the answer
You can attempt this question now. Sign in to view the answer key, explanations and discussion.Log in to check answerQuestion 39
Open questionECNAT2 marksNeeds review
In the figure shown, the
transistor acts as a switch. 
For the input
as shown in the figure, the transistor switches between the cut-off and saturation regions of operation, when T is large. Assume collector-to-emitter voltage at saturation
and base-to-emitter voltage
. The minimum value of the common-base current gain (
) of the transistor for the switching should be ________.Log in to check the answer
You can attempt this question now. Sign in to view the answer key, explanations and discussion.Log in to check answerQuestion 40
Open questionECNAT2 marksNeeds review
For the circuit shown, assume that the NMOS transistor is in saturation. Its threshold voltage
and its transconductance parameter
. Neglect channel length modulation and body bias effects. Under these conditions, the drain current
in mA is ____________. 
Log in to check the answer
You can attempt this question now. Sign in to view the answer key, explanations and discussion.Log in to check answer