GaAs has a greater density than silicon. The density of silicon is 2.33 gm/cm3 whereas for GaAs it is 5.32 gm/cm3.
12. Which has a low breakdown field?
A. silicon
B. GaAs
C. gallium
D. silicon and gallium
Answer: A
Silicon has a low breakdown field in the range of 3×105 V/cm whereas for GaAs it is 4×105 V/cm.
13. Which has a greater effective electron mass?
A. silicon
B. GaAs
C. free electron
D. gallium
Answer: A
Silicon has a greater effective electron mass than GaAs. Silicon has electron mass in the range of 0.97 times the mass of the free electron.
14. Which has low power dissipation?
A. CMOS
B. bipolar
C. GaAs
D. NMOS
Answer: A
CMOS has low power dissipation whereas bipolar has high and GaAs have medium power dissipation.
15. Which device has low input impedance?
A. CMOS
B. bipolar
C. GaAs
D. NMOS
Answer: B
A bipolar transistor has low input impedance and high drive current whereas CMOS and GaAs have high input impedance.
16. Which device has a low noise margin?
A. CMOS
B. bipolar
C. GaAs
D. NMOS
Answer: C
GaAs has a low noise margin whereas bipolar has a medium noise margin. CMOS has high noise margin than the other two devices.
17. ______ has a high packing density.
A. CMOS
B. bipolar
C. GaAs
D. CMOS and GaAs
Answer: D
CMOS and GaAs have high packing density whereas bipolar transistors have low packing density than CMOS and GaAs.
18. Which has low delay sensitivity to load?
A. CMOS
B. bipolar
C. GaAs
D. CMOS and GaAs
Answer: B
Bipolar transistors have low delay sensitivity to load and fan-out whereas CMOS and GaAs have high delay sensitivity to load, fan-in, and fan-out.
19. Which is a direct band-gap semiconductor?
A. CMOS
B. bipolar
C. GaAs
D. bipolar and GaAs
Answer: C
GaAs is a direct band-gap semiconductor and can be used as a good light-emitter whereas CMOS and bipolar are indirect band-gap semiconductors.
20. Factors significant in high-speed semiconductors are
A. carrier mobility
B. carrier saturation velocity
C. existence of semi-insulating substrate
D. all of the mentioned
Answer: D
FOr very high-speed operation in a semiconductor medium, three factors are significant – carrier mobility, carrier saturation velocity, and the existence of a semi-insulating substrate.
