Looking for help with question 3 – 6. The questions relate to semiconductors/BJTs.?

Bachelor of Engineerine in Electronic Engineering (Year-4)
Semiconductor

Devices

'

Problem Sheet #2 : BJT Desisn. Operation & Fabrication

I COMPLETE & HAND IN FOR

Question

I :-

draw and label the electrical symbol for a BJT. Illustrate and explain how a BJT can be configured
rimple amplifier. Draw and explain the associated IV characteristic.
t" ,.t
"
"r
Question 2 : Draw and label the cross-section of a modern BJT. Illustrate and explain the basic fabrication
r.q,rrr* f". thrs device. Further explain the function of each of the fotlowing components 9f the
(iii) the sinker diffrrsion'
structure: (i) the buried fuv"r, (ii) tt. epitaxial layer, (ii) the isolation wells,

Question 3 : Using a carrier concentration plot, illustrate and explain the internal operation of a PNP bipolar
type of
transistor structure; relate you answer to the typical IV characteristic exhibited by this
device.

Question 4 : With reference to Figure 2.1 (see overleaf): (i) explain what is meant by the term 'emitter injection
the
effrciency (y),, (iD .*ptui, what is meant by the term 'base transport factor (o1)' and calculate
current gain
explain what is meant by the term 'common base DC
value olthir
(aps),and calculate the value of this parameter, (iii) explain what is meant by the term 'DC current
gain (poc)' and calculate the value of this parameter for the structure shown.

p-r*ioJii)

Question 5 : (ii)
With reference to Figure 2.2: (i) identify each of the CMOS devices in the cross-section shown,
identiff the functioi of each of the CMOS devices present, (iii) identifu any parasitic bipolar
by the term
devices present in the cross-section shown, (iii) illustrate and explain what is meant
probability of latch-up can be significantly
latchup,lir; ,"r"u.ch a structural means by which the
reduced.

Question6:-

nrd I _-___.^c
a BJT structure for
Discuss in detail the design trade-off s that must be considered when optimizing
high-power versus high-frequency operation'

7/

N++

N

P+

Nr:

10l8cm-3

y:0.999

WE

:

1.0pm

Ns:

1016cm-3

Ls:

10pm

WB:

0.2ytm

Nc:

l0lacm-3

W6:

5pm

Figure-2.1 : Bipolar Transistor Cross-Section

Figure-2.2 : CMOS Integrated Circuit Cross-Section