Quiz3_PN_Junction

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University of Alabama, Huntsville *

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310

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Electrical Engineering

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Feb 20, 2024

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12/9/2020 Quiz: Quiz3 - Requires Respondus LockDown Browser + Webcam https://uah.instructure.com/courses/46230/quizzes/99996/take?preview=1 1/12 Quiz3 - Requires Respondus LockDown Browser + Webcam  This is a preview of the published version of the quiz Started: Dec 9 at 10:45am Quiz Instructions 2 pts Question 1 True False Carrier density in the depletion region of a PN junction is zero. 2 pts Question 2 True False Energy barrier across the PN junction increases during reverse bias. 2 pts Question 3 Diode built-in voltage increases with higher temperature.

12/9/2020 Quiz: Quiz3 - Requires Respondus LockDown Browser + Webcam https://uah.instructure.com/courses/46230/quizzes/99996/take?preview=1 2/12 True False 2 pts Question 4 True False Built-in voltage of a PN junction diode increases with doping density. 2 pts Question 5 True False PN junction is used as a rectifier in the electronic circuit. 2 pts Question 6 True False A solar cell produce more photo-current in the forward bias than the reverse bias.

12/9/2020 Quiz: Quiz3 - Requires Respondus LockDown Browser + Webcam https://uah.instructure.com/courses/46230/quizzes/99996/take?preview=1 3/12 2 pts Question 7 True False Highly doped PN junction is more susceptible to reverse breakdown than the lightly doped junction. 2 pts Question 8 True False An LED emits more light in forward bias than reverse bias. 2 pts Question 9 True False The magnitude of electric field in a PN junction diode is minimum under equilibrium. 2 pts Question 10

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12/9/2020 Quiz: Quiz3 - Requires Respondus LockDown Browser + Webcam https://uah.instructure.com/courses/46230/quizzes/99996/take?preview=1 4/12 True False PN junction dissipates more power in the reverse bias than the forward bias. 4 pts Question 11 250 nm 100 nm 150 nm 200 nm A PN junction diode has a depletion width of 100 nm at equilibrium. What will be its depletion width when it is reverse biased with -2V? (Assume built-in voltage = 0.67 V) 4 pts Question 12 0.4V 0.3V 0.5V 0.2V If the current through a PN junction diode is 1 mA, what is the applied voltage, V ? (assume diode saturation current = 10 nA and V is applied on the P-side whereas N- side is grounded) A A

12/9/2020 Quiz: Quiz3 - Requires Respondus LockDown Browser + Webcam https://uah.instructure.com/courses/46230/quizzes/99996/take?preview=1 5/12 4 pts Question 13 Wn =100 nm and Wp = 300nm Wn =400 nm and Wp = 400nm Wn =200 nm and Wp = 200nm Wn =300 nm and Wp = 100nm Assume that the N-side doping density of a PN Junction diode is three times the doping density in the P-side. If the total depletion width = 400 nm, which of the following is correct? (Wn = depletion width in N-side and Wp = depletion width in P- side) 4 pts Question 14 Electric field magnitude is maximum exactly at the physical junction. Electric field direction is from N-side to the P-side All the options are correct Electric field magnitude increases with reverse bias Which of the following is true about the electric field at the PN junction? 4 pts Question 15 Which of the following is true regarding the electric field direction in a PN junction diode?

12/9/2020 Quiz: Quiz3 - Requires Respondus LockDown Browser + Webcam https://uah.instructure.com/courses/46230/quizzes/99996/take?preview=1 6/12 The direction of electric field is always from N-side to P-side The direction of electric field depends on the applied bias across the junction The direction of electric field is always from P-side to N-side Electric field direction in forward bias is opposite the field direction in reverse bias 4 pts Question 16 0 A 1 mA 1 nA Not enough information What is the magnitude of current through a PN junction diode under equilibrium? Assume diode saturation current = 1 nA. 4 pts Question 17 Capacitance of a PN junction diode increases with higher reverse voltage Capacitance of a PN junction diode increases with minority carrier lifetime Capacitance of a PN junction diode increases with higher electron mobility Capacitance of a PN junction diode increases with higher doping Which of the following is true regarding the capacitance of an PN junction diode?

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12/9/2020 Quiz: Quiz3 - Requires Respondus LockDown Browser + Webcam https://uah.instructure.com/courses/46230/quizzes/99996/take?preview=1 7/12 4 pts Question 18 Maximum resistivity point is on N-side Electric field is more in the P-side compared to N-side Most of the depletion layer is on the P-side Most of the band-bending is on the N-side Consider a PN junction with N-side doping density much greater than the P-side. Which of the following is true? 4 pts Question 19 Diode saturation current increases with higher temperature Diode resistance increases with higher temperature Diode built-in voltage increases with higher temperature All the options are correct Which of the following correctly describes the effects of temperature on a PN junction diode? 4 pts Question 20 If the built-in voltage of a symmetrically doped (N = N ) Silicon PN junction diode = 0.6V at room temperature; what is the doping density? A D

12/9/2020 Quiz: Quiz3 - Requires Respondus LockDown Browser + Webcam https://uah.instructure.com/courses/46230/quizzes/99996/take?preview=1 8/12 1 0 cm 1 0 cm 1 0 cm 1 0 cm 17 -3 16 -3 15 -3 18 -3 4 pts Question 21 1 nA Not enough information 10 nA 1 mA What is the magnitude of current through a PN junction diode which is reverse biased at -1V? Assume diode saturation current = 10 nA 4 pts Question 22 N-side is connected to positive voltage and P-side is grounded Polarity of voltage connection does not matter, only voltage magnitude decides forward biasing P-side is connected to negative voltage and N-side is grounded N-side is connected to negative voltage and P-side is grounded Which of the following is a necessary condition for a forward biased PN junction diode?

12/9/2020 Quiz: Quiz3 - Requires Respondus LockDown Browser + Webcam https://uah.instructure.com/courses/46230/quizzes/99996/take?preview=1 9/12 4 pts Question 23 Low-band gap semiconductor Asymmetric doping density on N and P side Diode with higher minority carrier lifetime All the options are correct A solar cell is made of a PN junction diode. Which of the following will improve solar cell's output current? 4 pts Question 24 Design the diode with asymmetric doping density on the N and P side Design the diode with higher electron/hole mobility Design the diode with higher doping density Design the diode with symmetric doping density in the N and P-side High electric field in a PN junction degrades diode reliability. Which of the following strategy you will take to minimize the max field in the diode keeping the built-in voltage same? 4 pts Question 25 Which of the following is true for a light emitting diode (LED)?

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12/9/2020 Quiz: Quiz3 - Requires Respondus LockDown Browser + Webcam https://uah.instructure.com/courses/46230/quizzes/99996/take?preview=1 10/12 Blue LED is made of higher bandgap semiconductor than red LED Doping density of blue LED is lower than red LED Blue LED is made of lower bandgap semiconductor than red LED Doping density of blue LED is higher than red LED 4 pts Question 26 Higher the built-in voltage more is diode saturation current Higher the minority carrier lifetime more is saturation current Higher the diode saturation current more is the leakage during reverse bias Higher the doping density more is diode saturation current Which of the following is true regarding the diode saturation current? 4 pts Question 27 Both N and P side are doped with donor atoms P-side is doped with acceptor atoms whereas N-side is doped with donor atoms Both N and P side are doped with acceptor atoms P-side is doped with donor atoms whereas N-side is doped with acceptor atoms Which of the following is true regarding the dopant atoms in a PN junction diode? 4 pts Question 28

12/9/2020 Quiz: Quiz3 - Requires Respondus LockDown Browser + Webcam https://uah.instructure.com/courses/46230/quizzes/99996/take?preview=1 11/12 All the options are correct Resistivity of a PN junction reduces in the reverse bias Resistivity of depletion region is lower than the neutral region Resistivity of a PN junction reduces in the forward bias Which of the following is true regarding the resistivity of a PN junction diode? 4 pts Question 29 30000 V/cm 30 V/cm 3000 V/cm 300 V/cm If a PN junction diode has a built-in voltage of 0.75V and total depletion width = 500 nm, what is the magnitude of peak electric field in the diode? 4 pts Question 30 Not enough information Forward bias Reverse bias If the depletion width of a symmetric (N = N = 10 cm ) Silicon PN junction diode is 1 micrometer, what is the bias condition? A D 17 -3

12/9/2020 Quiz: Quiz3 - Requires Respondus LockDown Browser + Webcam https://uah.instructure.com/courses/46230/quizzes/99996/take?preview=1 12/12 Quiz saved at 10:45am Equilibrium Submit Quiz

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