11. Schottky barrier is created due to the difference in
A. voltages
B. thickness
C. work function
D. density
Answer: C
The Schottky barrier is an electrostatic potential barrier created at the interface as a result of the difference in the work function of the two materials.
12. As the separation between metal-semiconductor surface is reduced, induction charge
A. increases
B. decreases
C. remains constant
D. is not affected
Answer: A
As the separation between metal-semiconductor surfaces is reduced, the induction charge in the semiconductor increases, and also the space charge layer widens.
13. In MESFET for gate _____ junction is used.
A. PNP junction
B. NPN junction
C. Schottky junction
D. n junction
Answer: C
The metal-semiconductor field-effect transistor is similar to JFET. In this instead of using the PN junction for the gate, the Schottky gate is used.
14. MESFET is constructed in
A. SiC
B. InP
C. GaAs
D. All of the mentioned
Answer: D
MESFET is constructed in compound semiconductor technologies lacking high-quality surfaces such as GaAs, InP, and SiC.
15. Gallium arsenide crystals are grown from
A. boron oxide
B. silicon oxide
C. silicon nitride
D. boron nitride
Answer: D
The growth of gallium arsenide crystals from high purity boron nitride cubicles is becoming the primary growth technique.
16. Wafers in GaAs fabrication are thermally unstable.
A. true
B. false
Answer: B
The fabrication of GaAs includes the production of round wafers and they are thermally stable and have superior semi-insulating properties.
17. The sequence of the steps followed in the fabrication of GaAs is
A. lapping
B. polishing
C. grinding
D.All of the above
Answer: D
The steps followed in the fabrication of GaAs are grinding the As-grown boules, wafering, edge rounding, lapping, polishing, and then wafer scrubbing.
18. Which devices are fabricated using a planar process?
A. enhancement mode MESFET
B. depletion mode MESFET
C. enhancement mode MOSFET
D. depletion-mode MOSFET
Answer: B
The depletion-mode devices are fabricated using a planar process where n-type dopants are directly implanted into semi-insulating GaAs.
19. Threshold voltage can be varied by
A. varying impurity concentration
B. varying doping level
C. varying channel length
D. varying source voltage
Answer: B
Threshold voltage in GaAs can be varied by varying the channel thickness and the doping level of the active region.
20. Stable native oxide was produced by
A. oxidation of silicon
B. oxidation of gallium
C. oxidation of boron
D. oxidation of aluminum
Answer: A
The driving force of silicon technology was brought about as the result of the presence of stable native oxide which was readily produced through the oxidation of silicon.
