VLSI Multiple Choice Questions on “Technology Development in VLSI Structures-1 “.
1. The GaAs fabrication has _________ gate geometry.
A. less than one micron
B. less than two micron
C. more than one micron
D. more than two micron
Answer: A
Clarification: The GaAs fabrication has characteristics such as having less than on-micron gate geometry and less than two-micron metal pitch.
2. The GaAs structure has upto _______ metal.
A. two-layer
B. three-layer
C. four-layer
D. one-layer
Answer: C
Clarification: The GaAs fabrication has the feature of having four-layer metal and four-inch diameter wafer.
3. Electron mobility of gallium arsenide is _______ that of silicon.
A. greater than
B. lesser than
C. same as
D. does not depend on
Answer: A
Clarification: Electron mobility of gallium arsenide is six to seven times that of silicon resulting in very fast electron transit times.
4. Saturated drift velocity of gallium is _______ to that of silicon.
A. greater
B. lesser
C. approximately same
D. does not depend on
Answer: C
Clarification: Saturated drift velocity of gallium and silicon are approximately equal. For GaAs saturation velocity occurs at a lower threshold field than for silicon.
5. Larger energy bandgap _____ parasitic capacitances.
A. increases
B. decreases
C. maintains constant
D. does not affect
Answer: B
Clarification: Large energy bandgap offers bulk semi-insulating substrate and minimizes parasitic capacitances and allows easy electrical isolation.
6. In gallium arsenide, radiation resistance is
A. stronger
B. weaker
C. absent
D. very weak
Answer: A
Clarification: In gallium arsenide radiation resistance is stronger due to the absence of gate oxide to trap charges.
7. In gallium arsenide, wider operating temperature range is possible.
A. true
B. false
Answer: A
Clarification: In gallium arsenide, wider operating temperature range is possible due to the larger bandgap. GaAs devices are tolerant to wide temperature variations.
8. _______ can be used as light emitters.
A. forward biased pn junction
B. reverse biased pn junction
C. forward biased pnp junction
D. reverse biased pnp junction
Answer: A
Clarification: Direct bandgap of GaAs allows efficient radiative recombination of electrons and holes and thus forward biased pn junction can be used as light emitters.
9. In GaAs __________ has more intrinsic mobility.
A. electron
B. holes
C. proton
D. neutron
Answer: A
Clarification: In GaAs, electrons have intrinsic mobility of 8000 cm^2/V.sec whereas in silicon holes has more intrinsic mobility as 500 cm2/V.sec.
10. Which has greater intrinsic resistivity?
A. silicon
B. gallium arsenide
C. gallium
D. silicon and gallium
Answer: B
Clarification: Gallium arsenide has greater intrinsic resistivity of 1×108 ohm.cm whereas silicon has intrinsic resistivity of 2.2×105 ohm.cm.
11. Silicon has a greater density than GaAs.
A. true
B. false
Answer: B
Clarification: GaAs has greater density than silicon. Density of silicon is 2.33 gm/cm3 whereas for GaAs it is 5.32 gm/cm3.
12. Which has low breakdown field?
A. silicon
B. GaAs
C. gallium
D. silicon and gallium