Consider the following assertions. $$S_1$$: For the Zener effect to occur, a very abrupt junction is required $$S_2$$: For quantum tunneling to occur, a very narrow energy barrier is required. Which of the following is correct?(GATE 2008 || EC || NAT ||1 MARK)

S1 and S2 are both true and S2 is a reason for S1.

S1 and S2 are both true but S2 is not a reason for S1.

GATE EC||ELECTRONIC DEVICES AND CIRCUIT||DEVICE TECHNOLOGY||PYQS(2000-2025)

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Question 1

Choose proper substitutes for X and Y to make the following statements correct. Tunnel diode and Avalanche photodiode are operated in X bias and Y bias respectively

(GATE 2003 || EC || MCQ ||1 MARK)

X : reverse, Y : reverse
X : reverse, Y : forward
X : forward, Y : reverse
X : forward, Y : forward

Question 2

Match items in Group-1 with items in Group-2, most suitably.

Group-1

P. LED

Q. Avalanche

R. Tunnel diode

S. LASER

Group-2

1. Heavy doping

2.Coherent radiation

3.Spontaneous emission

4. Current gain

(GATE 2003 || EC || MCQ ||1 MARK)

P - 1; Q – 2; R – 4; S–3
P – 2; Q –3; R – 1; S–4
P – 3; Q – 4; R –1; S–2
P – 2; Q – 1; R – 4; S–3

Question 3

Find the correct match between Group 1 and Group 2

Group 1

E. Varactor-diode

F. PIN diode

G. Zener diode

H. Schottky diode

Group 2

1. Voltage reference

2. High-frequency switch

3. Tuned circuits

4. Current controlled attenuator

( GATE 2006 || EC || MCQ ||1 MARK)

E–4, F–2, G–1, H–3
E–2, F–4, G–1, H–3
E–3, F–4, G–1, H–2
E–1, F–3, G–2, H–4

Question 4

Group I lists four types of p-n junction diodes. Match each device in Group I with one of the options in Group II to indicate the bias condition of that device in its normal mode of operation.

Group I Group II

P. Zener Diode 1. Forward bias

Q. Solar cell 2. Reverse bias

R. LASER diode

S. Avalanche Photodiode

(GATE 2008 || EC || MCQ ||1 MARK)

P–1, Q–2, R–1, S–2
P–2, Q–1, R–1, S–2
P–2, Q–2, R–2, S–1
P–2, Q–1, R–2, S–2

Question 5

Group I lists four different semiconductor devices. Match each device in Group I with its characteristic property in Group II.

Group-I	Group-II
(P) BJT	(1) Population inversion
(Q) MOS capacitor	(2) Pinch-off
(R) LASER diode	(3) Early effect
(S) JFET	(4) Flat band voltage

(GATE 2008 || EC || MCQ ||1 MARK)

P-3, Q-1, R-4, S-2
P-1, Q-4, R-3, S-2
P-3, Q-4, R-1, S-2
P-3, Q-2, R-1, S-4

Question 6

Consider the following assertions.

[Tex]S_1[/Tex]: For the Zener effect to occur, a very abrupt junction is required

[Tex]S_2[/Tex]: For quantum tunneling to occur, a very narrow energy barrier is required. Which of the following is correct?

(GATE 2008 || EC || NAT ||1 MARK)

Only S₂ is true.
S₁ and S₂ are both true but S₂ is not a reason for S₁.
S₁ and S₂ are both true and S₂ is a reason for S₁.
Both S₁ and S₂ are false.

Question 7

A Zener diode, when used in voltage stabilization circuits, is biased in

(GATE 2011 || EC || MCQ ||1 MARK)

reverse bias region below the breakdown voltage
reverse breakdown region.
forward bias region
forward bias constant current mode

Question 8

A pn junction solar cell of area 1.0 cm², illuminated uniformly with 100mW cm^-2, has the following parameters:

Efficiency = 15%, open circuit voltage = 0.7 V, fill factor
= 0.8, and thickness = 200 um. The charge of an electron 1.6 × 10^-19 C. The average optical generation rate (in cm^-3s^-1) is

(GATE 2020 || EC || MCQ ||1 MARK)

1.04 × 10¹⁹.
0.84 × 10¹⁹.
5.57 × 10¹⁹.
83.60 × 10¹⁹.

Question 9

A solar cell of area 1.0 cm², operating at 1.0 sun intensity, has a short circuit current of 20 mA, and an open circuit voltage of 0.65 V. Assuming room temperature operation and thermal equivalent voltage of 26 mV, the open circuit voltage (in volts, correct to two decimal places) at 0.2 sun intensity is ___.

(GATE 2018 || EC || NAT ||1 MARK)

0.59 to 0.63

Question 10

Red (R), Green (G) and Blue (B) Light Emitting Diodes (LEDs) were fabricated using p-n junctions of three different inorganic semiconductors having different band-gaps. The built-in voltages of red, green and blue diodes are V_R, V_G and V_B, respectively. Assume donor and acceptor doping to be the same (N_A and N_D) respectively in the p and n sides of all the three diodes.

Which one of the following relationship about the built-in voltages is TRUE?

(GATE 2018 || EC || MCQ ||1 MARK)

V_R > V_G > V_B
V_R < V_G < V_B
V_R = V_G = V_B
V_R > V_G < V_B

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