QEMICONDUCTORS

GOVERED TOPICS
TO
BE

(3 +
(OMMONICATTON IN
1
3. 2. 1.
[ONE])
5. 4. S
Atplation
Irensitors fAfication
Biesing f Biasing lN
Gpe
and +KAy
anaysis Semicondue
tors OPTICS
 Commonieation (sN)
"aconni antena
"Elements of a
communiaton stem ; anlenra’ L.anlenna
Sousce mesge Redevd mess
Sgra Jnfbmton
IRASMITERCoded
mege
Channl
Recievs
"Laghof
antenna

Signal info
info fosm
*
* Foopgothion of EmM JaNes
2 Ampiioaion 2. AmplFreahen Gocound uoave’ tos Loo sgras.
) Redeve
.chane -oise ve gides oven the Buhace. The war
indoceb a cussent on dhe qaound OveH ohich passe and
t is atenuated a a aebult of absosbHon of
"T9ansducen ’ voice Convet Coded Jhe eadh.
ene by
sgnal. The attenuon of Suyre wqve i wj th inc in ,
(3sliyq Loo kltye hi use kte ye mtta)
ONLOanted
oignal. Layes of atnosphene -
"Attenutton’ Loss of sength (amplihde )
(orposite of ampificadton) nessgheve TheunoepheISb due to
high heat
"Amplificahion ’ (amplihude ) st Groce satosphee Jas paute
Bandoidth’age of in uahich
gedeice
Sonise
opeales (ooles) <Tsioposphèe Phee

Layen
"Modulaion->Jo Supecimpoge Demodulaion
sodiaien Jonasphoe
Commoni ater
(batho ciy) Baitha dye hue iofo ko
apao tasua
(at the tecjeve)
Energy Band theory Semiconductors

Isolated atoms has discrete energy Classification have - ve temp.

coefficient of
levels resistance
When two atoms form bond 1 Conductors 1
C.B & VB Overlap Ra
Valence shell interact & form
energy bands
CB
e in VBcan Ternp ‘ nt(m)t
Energy Conduct simultaneously R4
Eç E,
e- e e
2 Semiconductors Ternp
CB E 1ev
1T
He all e- in VB
All valence e in V.B.
Fcc Structure
Temp Te Jump to CB
VB
Er’ Min Energy in CB
E,’ Max. energy in V.B. SI = 1.1 ev, Ge = 0.7 V) Group - 14
3 Insulator
E- EE, = Energy barGap he electron
Qkelin
= Forbidden Energy CB E,3 ev At ékinsulators
At roomn temp e
= materialdependent Lattice Energy < E jump to CB
Noe can reside (Intrinsic) VB
No free e conduct
Temp. T, gap der slightly.
)240
he
Ehandgap
 Sy ooNCS} Space uoave
by ionispheir LOS-bne of sigrt.
aeslechon (T"gR)) d-d
30-40 of sadiatornb,
To
R=Rote h , anlenna

(lonispheàt Lye ’3to 30 MH)

ats
onosphen * Amplitode Moduladion
TR
Reciev
"messoge -’ y3-Am Sin (ot)
ase
fomolag puse ignal. E (Ac+ Am Sin(wnt)) Sn ogt - )
Caseie uve-) = Aç Sin(Oct +) = Ac

Modolaton. *mebsage Sigal cxmududy

Signa
[I+(Am Sn (wmt) Sin (wot)
As.
Am
Fm >- Am{sin (omt) igomevic
Aeloton
A

mebSgje sg nal Loo()

Looks Jndex
ie1,
Less distoron,
(high()
CoS (to-t MA cos (aetjt
022
Max = HetAm " Laoe side.rg0,-0m)
Amin Ae-Am rvotag Upper side
Vmay
Ve+Vm
Vmin- Ve EVm

"Jmyp fosm for quc.

no' of tatBons
velength must be geter than hegt of anknra
Bankoidth2m)hessage sisad
Concept of Holes Classification of semicond uctors
1 2
Doped
External Impurities
Intrinsic Extrinsic e LowconcentrationBop
"Sie" Sie SiL Si". Sio. Si. e Pure form Si, Ge Similar sizedopant
|"Sjo Si Sji" Si Si. No external Impurities dopart
Occupy lattic points
Caseuet.
e Motion ‘ie n=nn
Temp. dependent current
T=hole motion‘TI, Group 13 elements t
Missing ein lattice Electrically neutral
Act as +ve Carriers
develops I,
Ntype P-type n, >>n,l,>>
Mobility isless than e Group 15 elements
Effective mass more than e doping
-

Bto B B

No physical charge on it. Electrically neutral Site

n >>n,>>Ih CB
CB

akptor le
E,= Fermilevel energy donar level
E, Shif to CB.
Near to
e

= weighted avg,energy of VE
EF near
VB
(Te
(Jec
occupied & vacant states to VB

Founi leve of P- typG oll holeoJomp

douonsaod and that ot -type
oil go uPed coher
9 upued depig
level s incHeased X> Guoup 15 elengt’5 Valencee X= GurougP(Rlemert-’ 3
baa ilke te dono inSigna->
Jo modulated
save silgne briig HighcOave’
aoBignal- mesbage
Stodiated
4oMHz above req- ’At At coave Bpace 3.
Suhace.
km) Jo4o0 (5 avdh trem
Sonesphee of
Range
MHE) 4oq’(30
do
Qveb’ Sky 2.
(MH2) teo than les» breq sove Guound 1.
THE) ib00 D0
do Hz 1T bbres
(
optole
GHz eodo
ktz hunded feo OaNes Rodio
1BGHZ) t on Les (beq Cable
MHz 450 Coaxial
cahenPoaled rcq of
RtnOge Bantuth
mediom.Transmisslon Bandclth
of
(6MHz) Banduoi
ofdh *
Signals Video #
(20KHe)
eg Banduhf
Signals: Benduoth
oh *
202) un mJee
Resistivity of semi - conductors
PN Junction Dlode
*1,=I+ junction recombination ? N
1=ne Av, +n, e Av, 1) e & Holes near
&B- + P* become expose
2) HoBes (P’NHi
Hi|
V
1 electron (N’P}P(PN)
1dit oo O00O
Tleee t]helh 3) B- &P+ become exposed.
4) EF set up at boundary
(depletion Region) P
P N
N-Type P-Type m
5) EF dir. N’P
Idiffusion
1 1 EF dft Idrift

leele
6) Ife jump,comes back, Jarit. 1 n
7) Potential developed in Region
Summary ’V, (Potential barrier
So for conduction biasing ooeo oeeoooeee'
potentlal
eletru free electron
hole

Apply external battery

PN Junction diode
Forward Bias = V, > V, (F.B) (Vp - Vy= + ve) |Barrier Heght)
F.B. R.B
Reverse Bias =V, <V(R.B) (V, - VE=- Ve)
 Kay OPTICS *
invoted. eluous.
"ight’ ogm of enegy Propgate d s EMW (ú)gmage u lateal objext.
Heght of
Gin Haght of image =and mioS
folaos aw fop of EMW) *Rotation cf object
17obj ot->
Tng in opp Sense.
Cesmic| -y X-Rayl U"v| Visbe siay Infamicso Rodio Jmg sotale
SayV I BG Y OR Hed ays
0Nesoave

(40c09) ( (zooon) cohen moOT Hotates

SncHeases

"MonochsOmatic Liq ht single begpeny. by b Image stotates

Sbe.
by 2e in Same
"oheneve ligt hals on ary susface 3 phenomenon cra
(. Rehiecton 2. Re7acicon 3. Absorbton)
# object’ POI of in cident ays, yelocty magnihcaton
ob)
+ Trage-’ pOT of elecked/ uelsraeted CUJS. cbj Smg also
Real dhject/ Real image-’ hen Joteeton of RkR s seal. no impat
Reblection (Lauss) moving ri to
TR
(ii) TR, RR,N al ie in Same plane. Jength
NOTE: al angles meObHed om clock prcblern ; 3f time inludes
muteb al
Nogind.. ex: obË = 2:15 ocloek
inidence
C noYmal nddence Guazing Obj =5:00 Smgll16 o- 25945)
clock Jmage
2-5 4hea 4f me Jndudes set. also
" Ref lechon som plane ex: obj = 8:20 s0 o clock
(i) (Jmage diestance
miecdistance) aloays.
objec Tncopt 1]? 5960 -8: 20 5C
Jmage
) h and image aways of opp natune, ÷3:39|0
yhi
"obj’sêl, SmgvihuaJ hoga.
 (DO

Higher
e ForwardBias Reverse Bias P’ Positive
1. Potential Barrier reduces 1. Potential Barrier increases N’negative
2. Width of depletion layer decreases (Vg 2. Width of depletion layer increases (Vet)
3. P-N junction provides very small 3. P -N junction provides high resistance. P’Negative
resistance N’ Positive

4. Forward current flow in circuit. (N)4. Reverse current lowincircuit. (P<N) Knee or cut in voltage
5. Order of forward current is milli 5. Order of current is micro ampere (Ge) Breakdown voltage
ampere MA) or Nano ampere (Si)
Ge =25V, Si =35 V
6. Mainly CASHiet
majority current flows 6. Mainly minority current flows.
VoBtmeter (V)
7. Forward Characteristic curve 7. Reverse Characteristic curve
-V, (volt) V P
MIlllameter
(mA) (mA) Switch
knec
voltage (a) forward bias
0
0.7 i.4
V, (volt) V'oltrmeter (V)

8. Forwardresistance * =017V 8. Reverse resistance

Ge03\. Milliameter
(mA) Switch

P N Symbol of PN Junction of diode

(b) revese bias
symbol
4 Hoo to ind Dynamic R.
/pote spcit IA
RDyoamic R at V-)?
ke justpr 6-5
de bi Slope
Isq value nke 4 12
 "Feld of vie’ Qhateve SPH6RICAL mIRROR
may be Size of
t aleoays foms eomplete msge Con vex muS

"Jnpastant Point : ZFoléGP.ais

"Sze of mirsos ^ Rehsectirg ase1 Pole
Concqve m9oy Gerve
SConveging mirror) Divegin

QSL for Solirg mrer (Plase) queottons Reflecion propextieb.

)) SHay to P:A ’ pas) theough tocs &o
L (Gog su ency of A iS Used
sed mijorly) appeast Jo pass oom focus.

(i) evebe ot
Jmages goes undeviated
() ay nddert cdt pole eblecs cbliqudy
20+9 ConceVe miseAo
2y+ okject Tnage Natune and ize
Case Real &Iny: , highiy diminshed
+Case (
Real & InN, diminhed
I
ondy
Jmegeb coill obj (o n¡ o
'Sarne Size , eal Snu:
fosm, Amagcs/gobjw c&oFbeyodc Recl & nv magnified
2. Tcoo ioros o3 Real &Tnv', highy magifi ed
Cabe l, 3 Smageb Coe2, vi) bjeo FaPbehind
I
coill foom "
Viadual & eyed, magnified.
I oill ´foom) Conv ex mio
) ot oo
vistoal &eHest, highy nigo
dii
Gi) at any distanceblo F& P
"I b/oP and oo. Ütual & Net, diminsed.
3, ohen doo misoTs indned at an
gee. obj at ang bisec,f=
* Misuor fomula
(f"g)
obat ahgs bissy a6o-)
evôn itegee odd stege not
ny
No Tmy =(-) (lsme f bhi sign covechon k ac
mhai
riessage sgm
(3 Baroidth 2 Um)
Types Tener Breakdown
Breakdown
of Avalanche Breaikdown Diode is R.B
Where covalent bonds of depletion Here covalent bonds of depletion layer are broken Ideal (Infinite Reverse Resistance
layer, itself break, due to high by collision of "Minorities" which acquire high PN
electric field of very high Reverse kinetic energy from high electric field of very
bias voltage. very high reverse bias voltage.

This phenomena takes place in This phenomena takes place in R Vr Rre

() P-N junction haing "High 1) P-N junction having "Low doping"
doping" main
2021 Xi) P-N junction having thick depletion layer RB
(i) P-N junction having thin ldeal given
depletion layer Real Case (High Res. in R.B)
Here P-N junction does not damage Here P-N junction damages permanently due to R
permanentBy abruptly increment of nminorities during
repetitive collisions.

Behaviour of diodes in F.B &R.B in electrical circuit Special Case

R
HilH R,
Behaviour of diodes Vext - Vknee In F.Bbias if V,ae iS not given or neither it ismentioned
Si = V=0.7 V it Si or Ge based diode
Diode Ge =Vnee= 0.3 V Rf F.B R,
FB Replace
linear (Diodenec) R Vext
(F8) Vest
(opposing batey) Rext t Rf
Vat Ru
Vext 4deal ase
(Vkne given neithex
Gie& Si meoticned )
Replace t ’ Sht iye
 Reflechion sules , * focal leglhs in medium
(i) Di of Tncident say oll be conbideed ve dis, ’lenses’ 'chan ge> ohen edium charge
! semas Same even b med
(in al dintance MeasLLed rom pole. ’ miYOY’
(N) distoances meaSuHEd to PA. NOTE
"Upusad = (tve) " doonuoMd (-ve) m=-ve
objyet
Jeal tveted opposite,
mag nification:
(m=-ve)w nyeted Same size Rebra chion
ho
b ea age
Sbending of light on moving from med to md,
(m=+v)~ect o\m|>1 ( ’ sarme) RI=Js¬r=C
Lvtua Smagenlged ,A’ chnge)
"Lateual mag nification " |m) <1 # Refra cive indec
diminished RI= Ao
(n,: h Ube oith
)sgn V Am
(for 'mede) forvcc um)

"LongitudionaJ magnitcahion: 12= ehoacive index of medz 4elatve to meda

only applicable
to (9-(matoa fos object of
"agniftoation mutple eechon thicknes *Laos ah sebvackon: sìng

9TR, RR, NR al lie in dame plane

velociy magni foathon ’ obj mevigg to Pf:
cbj ioving to Pa
"Sate denpen,mel. ) 8epeed
ight bends
" hen obj eS D’R
along prineipal axis R
(To bind masnification (ToLoaGHdB nosma) (ausay frem nosma)
bos Small dhicknes> bo extenderd hob * RebactB on rom Gikas slab
’ Solve Smage dist epfor A &B thireby(=e)
no
Smogc
(mg -tI)
Latera) h t =t.
CaS sin-7
 Jee2024u NNTE: To RamoJe AC Cenporert -’Tust like a cpao
Connect an idoctoy n
Seues oth Rod

Application of PN junction Diode Important Points

Rectifier efficiency :11Half=40.6%

Rectifier ACRectifierDC Full =80.2%
Half Wave : Input Freg. = 50 Hz, Repple v= 5O Hz
Input
There are twotypes of Recti6or Full Wave : Input Freq. = 50Hz, Ripple v= 100Hz
Is= lo/2| Half Igms =lo/V2| Full
oo00000
1) Half Wave Rectifier Output
A Ripple factor (HWR) r= 1.21
D
AAER AAAR (FWR)r= 0.48
-B B To remove AC component We use
iltet ckt
For positive half cycle For negative half cycle
IFilter Circuit Half Wave
Partial
2)Full Wave RectifierO000.00.OJ 'eWithout filter,
o00000D D Input/NCKT Rectifier Full Wave
DC
TdetIns de
R, R, D
Output
Output of ER,
D, D,
Tectifier
Output
For positive half cycle For negative half cycle
oubes (20)
halt () a or do usoent
Tine Potoc
(no dc CuHent passe
AC eusorerd
only 6oill ps thcyh Capacker)
 * Psisn and ts ypes
* Total tntenal Reblection
deiaion
cohen light move (D’R), trtets bends aoay om nosma
# RebU lts
at eemeHges iol to Suce beyond he angle ’ TIR
f Roex med=aH e
#o= gin *c= in- ()
" =ite -A
" gn TIR-’ no loss of Üntensily
ân Sieflecion fyom mìTOT Loss o O Conditon os minìnLSn deato:
oY Tebrachen om leess Sntensitg So(in =21-A= Qe-A)
tif) at &min ebered uy in psbm
VIBG yOR RI-L« Paale to base,
>inc deviaton
of PiSm at mËn
+A
Lao of Hevesbily H= Sin ( min
Din changes poth
ecoveb one
maximum devsakon CondiHOS at angle ot
deiaton 2i’max cn
(H eore? Helad) ) ohen be aeheived,
clgedig
#}sin-! 4+ Becond angle forma ight
angte of punch
angle of emegerce hen
bor crtical Cond f, optica) jree dence
calble.
Goazig Jnidence concept TIR n psm Li
Cane2. GI brom ohen A2n; (E then ot all
Casel, Grazing Incdence n
Dengsn med R thee coillbe TIR Jight oll not pb pism.
R
 , hemly deped
"operated at
on FFBody0olight emi in RB. Jee Q023 (Vee <Vzne)
LED PN junction diodes, on E.Bcondition,le jumps ove
depletion layer to combine with holes, they release Photo Diode
E-he
viste energy (lies is visible spectrum), hence Ernit light When light is incident on depletion
hc layer, bonds break & develop e-& hole O
Ereleased=
pair earlier saturation was due to
(LED mínority carrier, the current is
Dep Laye enhanced by the e- hole pairs
developed by light in dep. Regio
Koueent inceases tI(mA)
I(mA) F.B Other Reverse bias
Darkturneni
Zener Diode Application EF
v(Volt)

Pside N-side
(Order of ntensities)(b)
(a)
R.B
N
Representation In RB Sollar cell’ Develops cell Solar Cell Depletion
Can be operated is Vappied 2 Vzeaer reglon
Atypical illuminaled
F.B as well as R.Bis then current in diode Light Rays From sun p-ajunctíon solar cel!
in FBit behave like increase Rapidly No biasing(noVext gPpp
(a)
normal Diode
Reglonpj
IfaZener diode is in R.B Light Falls on dep.
bond fe & Hole
Ve(open circuitsoltage)
V, >V,Voltage Regular & current is charging Break The N
rapidly, then voltage pair) NShort circuit current
function across diode is e imove towardss N due to ER IV characteristics of a solar cell

very less
(Same o P c h o
The concentraltion
side prencmenan) (a Jee 2022,)

bdoy
 * Motion of object
* Thin psàsm ;-Fska (A <5) A’mal
)&- (u-1) A gall angle apox )Along Psincipal ois 2) long t
Dispesion om Poism
pie ymys PoA
1s spHng of ohite hghd rto
Tcolou, VI o P.ATmteral
Angua (E)
devìton dispesion(daya) # Dispeive o
Poien (o);Dim
S-4-1)A
Fo deviadton cothout
DisPESonnet Fos dispetbion (Hy-1)
coithout
ispesion) deviaien,’ net
Sarg 1+ ag2 =0 (deiajeny
’A'= -

Retracton som bpheiea Sutce

" Hadiu of eovadre
toom P.
Rt values utth bign aloays)
MagneeaHon;
Olteal mag @Lorgitodiona mag
hi
ho
+(Mong- ( )
"ony vald tor omall thicknes
tps Jage thidknes Sdve foy
both erd
 Boh10nd 2a4caemerd1’ 0P tantor peemit mere overt than PRP
Jue o RSn: npn’ myoy asoJeN’e
Coyyct erpln pnP’ma ’hde hee máun
of A. 2022
Stademert-2:e have grcae
mobility asachoqc caoues

Behaviour of Zener Diode in electrical CKT

Gue) Transistors
Three terminal two
R, Transfer of resistors
Forward Bias Casel
junction rnote
SNormal diode 14 R +R RB RB
C
P IL^)
P N Vneegiven
Or Rat
-0.7V Bn
0.7VEB t Bn
EB P
V=0.7 V short wire E
=0.3 V
(19BA)(99At
V R,at R = Forward 14
(198A)(99A)

Resistance R (2A)
Vat Ren (100 A)
Siva) Cagezi
(nothg (armplcalion) (:00A)
2001A
200A

R,
I,’twice, I,’twice; I, > >>I,
Reverse Bias (V, < V)(V-V,=-V) Bp
PN Normal diode
Case - 1 R.e R
Rreverse given Ras /p R o/p
Vext <V, other =0
(Rrevere =0)
CB (npn) CE (pnp)
Ren
*{Case -2) Comnon
PN
V Voltage Reglator
Rt
Replace the diodeby a
lsaturatlon opposing battery of
voltage (V) Rea
l(ut) R BUSe

nikab favesh
Ikuga Cwoiet
Kegq usent
(orposing Væ) emiten sdesc Gmilte sidese
 Medim size High diping
Application as an Amplifier Emitter

Smallest size Low doping

Base
Medium dopping
Vo/e =VcE =Vcc-IRc CB O/P Collector Largest size
basiS of
Transistor have two P - Njunction .g and J. On the
CE R.
N
junction condition transistor work in four regions
Collector - Base Region of Work1ng
intput Emitter - base
signal
Forward biased Reverse biased Active
LV< output signal Reverse biased Forward biased Inverse active

CE O/P Reverse biased Reverse biased Cutt off

common emitter amplifier NPN transistor Forward Biased Saturation

Forward biased
than the emitter.
I,’ Input (small current) The collector region is made physically larger
has to dissipate much gre ater power
Because collector
I ’ Large output
Application of transistor as a switch From transistors characteristics
Cut off
region
Acttve
(CE
(i) Input resistance rin =

VCE=Constant

(ii) Output resistance r= (SVCE

Saturation
regkon
Alc T=Constant
'st A

TrarsBe: charactenstic
(iii) Current gainß= \AlB CE=Constant

Jor Vg-0:7V i Vaghied <Vnee)

knee
o no cuseent devlop
Vi>o"V VoVke-IoRe)
I,-o Te-0 ootput Nee Qcive oteebn
+ Cusoet gain fo) Ic tnde Gan Woutput
IeE Crnput

E E
B --B B -B
-C
B
E E
B -B
Input Resistance Low (100 2) High (750 2)
Output Resistance Very High Hight
Current Gain (A, or ) B=lc/I, >1
a=l/ <1
Voltage Gain |A, =V/V,=IR/R, Ay =V/V,=IR/R
|A, =a RR, |Ay =BR/R,
Power Gain Ap = Po/P A, = Po/P,
A, =áR/R |Ap =B'R/R
Phase difference Same phase Opposite Phase
(B/w output and input)
B
B= 1-a,a= 1+ß
 Logic Gates
Logical input ’ Logical output
Follows Boolean Algebra 2) Combination (Universal) Gates
AND Gate ekbhi o.
1 Basic Gates A do outpet
Y 1. Nand
Input 2. Nor
(ek bhi 1 do D output (And + NOT)
-) B (OR + NOT)
A
-Y=A + B A Ao A
B
Gale B Not Gate () Bo y B

Truth Table
A B Nand B Nand
A Y 0 1 0 0
0 0 0 0 1 1 0 1 0
0 1 0 1 0 1 1 0 0
1 0 1 1 0 0 1 0 1 1 0
1 1 1 1
Y=A Y=A.B Y =A+B
Boolean Y=A+B Y=AB
Exp.
Shoat cisuâed She clclited
AND Gate NOR Gate

dNVERTER
 Important ldentities Useful Identities

() A+ AB = A (ii) A · (A + B) = A
OR AND NOT (iv) A -(Ã + B) = A -B
(i) A+ (AB) = A + B
1. A+0=A 4. A.0 =0 7. A + Ã=1 (v) A+ (B ·C) = (A + B)· (A + C)
+2. A+ 1=1 5. A. 1 =A 8. A. Å=0 (vi) (A + B)· (A + C) =A:C+B·A + B·C
3.A+ AA=A 46. A. A=A 1) 2) Ex-OR & Ex - Nor Gate
Ex- OR Ex - NOR
B Y
De Morgen's Law Y 0

B 0 1 0
Break the line charge the sign En-NDR E-0
(r) mglestet1
Exclusively = NoR
0
A + B=A. B #Y=A. B+ B.A 1 1 11
Y=A B +Y=A. B+ AB
A.B =A+B
A B Bx-0R Ex -NOR
(A. B)T- (A" B) + 0 Y= +BA = AB. B. A
=(A+B)+ 1 1
=(k+ B) (B +)
1 0 1

1 1 0 =(A+ B).(B +A) =(4+ B). (B +A)

= AB + AA + BB + BÃ