Match the following : Choose the correct answer from the codes given below:List – I List – II a. Gunn diode i. degenerate silicon b. Tunnel diode ii. n-type Ga As c. BJT iii. Silicon d. Diode (P-N junction) iv. \(I_o\left[\exp\left(\dfrac{qV}{kT}\right)-1\right]\)
a-ii, b-i, c-iii, d-iv
Three of the four entries name a material and one gives an equation, so the equation pairs itself first and the rest follow from what each device is made of.
a → ii. Gunn diode — n-type GaAs. The Gunn effect is not a junction effect at all; it needs a bulk semiconductor with a particular band structure, one having a low-energy central valley and a nearby satellite valley of higher effective mass. Electrons transferred to the upper valley become heavier and slower, so the drift velocity falls as the field rises — bulk negative differential resistance. Gallium arsenide (and InP) have that two-valley structure; silicon does not, which is why a Gunn diode cannot be made from it.
b → i. Tunnel diode — degenerate silicon. The word degenerate is the giveaway: both sides are doped so heavily (1019–1020 cm−3) that the Fermi level enters the bands and the junction becomes only ~10 nm wide, thin enough for electrons to tunnel through.
c → iii. BJT — silicon. The ordinary bipolar transistor is the classic silicon device; nothing exotic is required.
d → iv. P-N junction diode — the Shockley equation.
\(I=I_o\left[\exp\left(\dfrac{qV}{kT}\right)-1\right]\)
which describes the exponential rise in forward bias and the saturation at −Io in reverse.
The quickest route through the question. Pair d with iv immediately, since it is the only equation. Then note that "degenerate silicon" can only describe the tunnel diode — degeneracy is its defining feature — leaving plain "silicon" for the BJT and n-type GaAs for the Gunn diode. Two independent deductions settle all four.
Hence, the correct matching is a-ii, b-i, c-iii, d-iv.
Similar Questions
A PIN diode can not be used as
i. Microwave switch
ii. Microwave mixer
iii. Microwave detectorWhich is correct ?
________ diode is not used as a microwave mixer or detector.
Match the given lists :
List – I (Name of the Device) List – II (Application) a. Diode i. Rectification b. Tunnel diode ii. Microwave switching c. Zener diode iii. An oscillator d. PIN diode iv. Voltage regulation Codes :
Varacter diodes have the following properties :
A. Junction capacitance varies with bias voltage
B. Junction capacitance varies with time
C. Non linearity of varacter diodes makes them suitable for frequency multipliers
D. Linearity of varactor diode makes them suitable for frequency multipliers.
Choose the correct answer from the options given below:
In a tunnel diode, the degeneracy on the n-side can be expressed as
The static current voltage characteristics of a tunnel diode consist of
(a) Tunneling current and thermal current
(b) Thermal current and excess current
(c) Tunneling current only
(d) Tunneling current, excess current and thermal current
Out of these which are correct ?
A TRAPATT diode has the doping concentration NA = 2 x 1015/cm3 and a current density of 20 kA/cm2. The value of avalanche zone velocity is given by :
Assertion (A) : The Gunn diode characteristics shows the region of negative resistance.
Reason (R) : The Gunn diode is made of n-type and p-type degenerate semiconductor.
Select your answer using the codes given below.
Which of the following statements are correct for Tunnel Diode ?
(a) 1 impurity atom in 103 atoms
(b) Very high doping in both p and n regions
(c) 1 impurity atom in 108 atoms
(d) used as a voltage controlled devices
Out of the above, the following is the correct answer :
Which of the following statements are true for a zener diode ?
(a) The voltage across the zener resistance is zero.
(b) The diode is used as a constant voltage device.
(c) The diode is used as a varactor diode.
(d) The diode is formed of heavily doped p and n-type semiconductor.
Options :
Important Questions from Types of Diode
A PIN diode can not be used as
i. Microwave switch
ii. Microwave mixer
iii. Microwave detectorWhich is correct ?
________ diode is not used as a microwave mixer or detector.
Match the given lists :
List – I (Name of the Device) List – II (Application) a. Diode i. Rectification b. Tunnel diode ii. Microwave switching c. Zener diode iii. An oscillator d. PIN diode iv. Voltage regulation Codes :
Varacter diodes have the following properties :
A. Junction capacitance varies with bias voltage
B. Junction capacitance varies with time
C. Non linearity of varacter diodes makes them suitable for frequency multipliers
D. Linearity of varactor diode makes them suitable for frequency multipliers.
Choose the correct answer from the options given below:
In a tunnel diode, the degeneracy on the n-side can be expressed as
