A. first-level metal phase
B. second-level metal phase
C. encapsulation phase
D. ion implantation phase
Answer: C
The encapsulation phase is the first phase and it includes wafer preparation. Encapsulation is a process of deposition of first-level insulator Si3N4.
122. Steps involved in the ion implantation phase are
A. metallization
B. anneal
C. alignment mark mask
D. lift-off
Answer: B
Anneal is a process involved in the ion implantation phase along with other processes like si+ implant mask, channel implant, source-drain mask, etc.
123. For the formation of E-MESFET _______ is used.
A. n- implantation
B. n+ implantation
C. p- implantation
D. p+ implantation
Answer: A
An n- implantation is used for the formation of E-MESFET and n+ implantation for the formation of D-MESFET.
124. To activate a dopant, _______ is necessary.
A. low-temperature stable gate
B. low-temperature stable drain
C. high-temperature stable gate
D. high-temperature stable drain
Answer: C
The anneal cycle requires a stable temperature of 850 degrees Celcius to activate the dopants it is necessary to choose a high-temperature stable gate.
125. The voltage swing for the Schottky barrier gate should be
A. low
B. high
C. very high
D. very low
Answer: A
Schottky barrier gates on GaAs cannot be forward biased above 0.7 to 0.8 volt, the permissible voltage swing should be relatively low.
126. The E-MESFET is defined by the intersection of
A. red and yellow masks
B. green and red masks
C. brown and red masks
D. green and yellow masks
Answer: B
E-MESFET is defined by the intersection of green and red masks and D-MESFET is defined by the intersection of green, red, and yellow masks.
127. E-JFET technology has
A. low voltage swing
B. high current swing
C. high power requirements
D. high voltage swing
Answer: D
E-JFET technology for ultra-high-speed VLSI has reduced power requirements with larger logic voltage swings.
128. In a CE-JFET, the ratio of electron mobility to hole mobility is equal to
A. 4
B. 10
C. 5
D. 20
Answer: B
In a CE-JFET, the ratio of effective channel electron mobility of the n-channel device to hole mobility of the p-channel device is equal to 10.
129. An equal number of p and n devices in a device will consume
A. small area
B. large area
C. all of the mentioned
D. none of the mentioned
Answer: B
The circuits requiring equal numbers of p and n devices will consume large areas. Thus one must use other design methods such as precharge techniques.
130. In high electron mobility transistor, the electrons are
A. far apart
B. high mobility
C. nearby and low mobility
D. far apart and high mobility
Answer: B
The electrons in high electron mobility transistors are spatially separated from ionized donors and they exhibit high mobility.
131. MESFETs are _______ modulation devices.
A. channel area
B. channel voltage
C. channel current
D. channel variation
Answer: A
MESFETs are channel area modulation devices and they depend upon the capacitance of the Schottky barrier.
132. Gallium arsenide has _____ regions of operation.
A. two
B. three
C. four
D. five
Answer: B
Gallium arsenide devices have three regions of operation – cutoff, linear, and saturation.
133. Drain to source current is due to
A. flow of majority carriers from drain to source
B. flow of minority carriers from drain to source
C. flow of majority carriers from source to drain
D. flow of majority carriers from drain to source
Answer: D
The current Ids results due to the flow of electrons, the majority carrier from source to drain. Ids can be given as the ratio of charge induced in the channel to electron transit time.
134. Transit time can be given as the ratio of
A. channel length to velocity
B. electron distance to velocity
C. source length to velocity
D. drain length to velocity
Answer: A
The transit time is given as the ratio of channel length to velocity and the carrier velocity can be further given as the product of electric field and electron mobility.
135. The average potential is given as
A. Vgs – Vt
B. 0.5(Vgs – Vt)
C. 0.25(Vgs – Vt)
D. 2(Vgs – Vt)
Answer: B
The average potential difference between the gate and the channel (VgB. owing to the shape of the depletion layer can be given as 0.5(Vgs-Vt).
136. Average electric field is _______ to implant depth.
A. directly proportional
B. indirectly proportional
C. does not depend
D. exponentially dependent
Answer: B
The average electric field is indirectly proportional to implant depth and this electric field can be given as (Vgs-Vt)/a.
137. The range of kp in MESFET is
A. 0.1 to 1 mA/V2
B. 1 to 5 mA/V2
C. 0.1 to 0.5 mA/V2
D. 0 to 1 mA/V2
Answer: C
β is a common parameter used in MESFET and it is denoted by kp. Kp is in the order of 0.1 to 0.5 mA/V2.
138. The hyperbolic tangent function is used to describe the
A. channel conductance
B. channel length
C. channel strength
D. channel depth
Answer: A
The hyperbolic tangent function tanh(aVds) is used to describe the channel conductance at the low drain to source voltage Vds.
139. The magnitude of the depletion region decreases when
A. Vgs decreases
B. Vgs increases
C. Vds increases
D. Vds decreases
Answer: B
When the gate to source voltage Vgs increases, the magnitude of the depletion region beneath the gate decreases.
140. Current saturation occurs when
A. Vgs < Vt
B. Vgs > Vt
C. Vgs > Vds
D. Vgs = Vt
Answer: A
When Vgs < Vt the increase in the drain to source voltage above the saturation voltage leads to current saturation.
