THEORETICAL AND APPLIED ELECTRICAL ENGINEERING VOLUME: 20 |NUMBER: 1 |2022 |MARCH
Impac o Wo k Func ion Tunabili y on The mal and RF
Pe o mance o P- ype Window Based Junc ionless
T ansis o
P iyansh TRIPATHI 1, Na end a YADAVA2, Mangal Deep GUPTA1,
Rajee Kuma CHAUHAN 1
1Depa men o Elec onics and Communica ion Enginee ing, Madan Mohan Mala iya Uni e si y o
Technology, Deo ia Road, Go akhpu , 273016 U a P adesh, India
2Depa men o Elec onics and Communica ion Enginee ing, Ins i u e o Enginee ing & Technology,
Deen Dayal Upadhyay Go akhpu Uni e si y, Go akhpu , 273009 U a P adesh, India
p iy[email p o ec ed], na end ayada [email p o ec ed], [email p o ec ed],
kc[email p o ec ed]
DOI: 10.15598/aeee. 20i1.4258
A icle his o y: Recei ed Jun 10, 2021; Re ised Oc 17, 2021; Accep ed Oc 19, 2021; Published Ma 31, 2022.
This is an open access a icle unde he BY-CC license.
Abs ac . The choice o ga e me al echnology o
junc ionless ansis o s needs o ha e di e se cha ac-
e is ics as me als ha e dis inc wo k unc ions and
hence, hey show incompa ibili y while ailo ing h esh-
old o he de ice. In such a scena io, bime allic s acked
ga e can be a p omising candida e o p esen wide
ange o unable wo k unc ions equi ed o nano-
egime junc ionless ansis o s. This pape explo es he
elec onic phenomena occu ing a me al-me al in e -
ace and he impac o Pla inum (P )/Ti anium (Ti)
bime allic s acked ga e-based wo k unc ion unabil-
i y on he RF and he mal pe o mances o p- ype
window-based Silicon on Insula o Junc ionless T an-
sis o (SOI JLT) using nume ical simula o SILVACO
ATLAS. The pa ame e s conside ed o pe o mance
e alua ion a e ON-s a e cu en (ION ), OFF-s a e cu -
en (IOF F ), ION /IOF F a io, ansconduc ance (gm),
cu o equency ( T), T ansconduc ance F equency
P oduc (TFP), In insic Ga e Delay (IGD), in in-
sic gain (AV), and Global De ice Tempe a u e (GDT).
The gm, T, TFP, AVand GDT imp o e o modi-
ied o e con en ional in he ON s a e a highe wo k
unc ion, while IGD imp o es a lowe wo k unc ion.
The imp o emen s o 11.7 % and 2.21 % a e ob ained
in maximum gmand T, espec i ely, o modi ied an-
sis o o e con en ional. The indings sugges ha
bime allic s acked ga e modi ied SOIJLT is a be e op-
ion han con en ional o low-powe RF applica ion.
Keywo ds
Bime allic s acked ga e, Junc ionless T ansis-
o (JLT), Radio F equency (RF), Silicon-on-
Insula o (SOI), he mal pe o mance and un-
able wo k unc ion.
1. In oduc ion
Minia u iza ion o MOS de ices aces majo challenges
such as Sho Channel E ec s (SCEs) in he nanoscale
egime [1]. Downscaling o in e sion mode FET de-
ices has led o c ea ion o e ec s like ho ca ie
e ec , D ain-Induced Ba ie Lowe ing (DIBL), poo
sub h eshold swing, e c. inside he de ice due o which
pe o mance has deg aded [1]. Ul a-shallow junc ion
is one o he solu ions o SCEs in he in e sion mode
de ices bu is e y complex and di icul om ab ica-
ion cos and p ocess poin s o iew [2]. The e o e, in
2010, esea che s came up wi h a new de ice, popu-
la ly known as “Junc ionless FET (JLFET)” o “ga ed
esis o ”, as a plausible solu ion o in e sion mode de-
ices [3]. I is hea ily doped semiconduc o de ice wi h
sou ce, channel, and d ain and all h ee a e doped wi h
he same uni o m doping ype and same concen a ion
[3]. Hence, he e is no p-n junc ion exis ing inside he
semiconduc o de ice. The ope a ion o his ga ed e-
sis o shi s om olume deple ion (o channel egion
in OFF s a e) in o pa ial deple ion and subsequen ly
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in la band condi ion and accumula ion egion wi h
he applica ion o ga e ol age [3].
Wo k unc ion is conside ed as one o he impo -
an pa ame e s o he selec ion o ga e me al ma e-
ial. The ga e elec ode wo k unc ion is u ilized as an
e icien ool o u n o he JLFETs by accomplish-
ing olume deple ion in he OFF s a e [4]. As he
ac i e laye in JLFET is hea ily doped, he ull de-
ple ion is achie ed in JLFET a VGS = 0 V. A ga e
elec ode wi h a high wo k unc ion (>= 5.1eV) is e-
qui ed o n-JLFETs, while one wi h low wo k unc ion
(<= 4.1eV) is equi ed o p-JLFETs [4]. This is in
di ec con as o he wo k unc ion equi emen s o
con en ional FET de ices [5]. In e es ingly, a sui able
ange o wo k unc ions (5.0 eV o 5.3 eV), also e med
as wo k unc ion window, has been sugges ed o ob ain
op imum pe o mance om junc ionless ansis o o
low-powe applica ions in a nanoscale egime [6]. The
e ec o single me als on RF pe o mance o junc ion-
less ansis o s has al eady been p esen ed in [7].
The SOI JLTs (Silicon-on-Insula o Junc ionless
T ansis o s) ha e he plana a chi ec u e compa i-
ble wi h Complemen a y Me al Oxide Semiconduc o
(CMOS) echnology, and hey ha e a single op ga e.
The polysilicon ga es ha e been eplaced by he me al
ga es due o he poly-deple ion e ec s and he pen-
e a ion o dopan s h ough he ga e dielec ic laye
[8]. The a ailable op ions o me als ha e di e en wo k
unc ions which a e sui able o n- ype and p- ype JLTs
[9]. The bene i o polySi ga e is ha i s e ec i e wo k
unc ion (EWF o Φme ) could be modi ied depending
on doping concen a ion, bu he pu es me als ha e
inhe en alue, so hei EWF canno be modi ied [10].
I some me al has he equi ed alue o wo k unc ion
needed o he desi ed h eshold ol age a ga e, hen
he e a e p oblems wi h i s he mal s abili y and ad-
hesi eness o dielec ic and semiconduc o ma e ials.
To ailo he h eshold ol age o he de ice, a s ong
app oach is ca ied ou when he ga e ma e ial should
ha e a unable wo k unc ion [5]. The e o e, ga e me -
als wi h unable wo k unc ion a e highly p e e able o
CMOS in eg a ion [11].
Va ious ga e elec ode echnologies o achie e un-
able wo k unc ion ha e been in es iga ed, such as
me al silicides [12], me al ni ides [13], [14] and [15],
bina y me al alloys [16], [17], [18] and [19] and bime al
s acks [20], [21] and [22]. Among hese, bime allic
s acked ga e has shown a wide ange o wo k unc-
ion unabili y and ease o deposi ion [20].
This pape aims o explo e he elec onic phenom-
ena aking place a me al-me al in e ace. Then,
he impac o Pla inum (P )/Ti anium (Ti) bime allic
s acked ga e-based wo k unc ion unabili y is s ud-
ied on he RF and he mal pe o mance o p- ype
window-based SOI JLT. The pa ame e s conside ed o
pe o mance e alua ion a e ON cu en (ION ), OFF-
s a e cu en (IOF F ), ansconduc ance (gm), cu o
equency ( T), T ansconduc ance F equency P od-
uc (TFP), In insic Ga e Delay (IGD), in insic gain
(AV), and Global De ice Tempe a u e (GDT). The
emaining pa o his pape is o ganized as ollows:
Sec. 2. explains he elec onic phenomena ak-
ing place a he me al-me al in e ace. The p oposed
de ice s uc u e, i s p ocess low and i s simula ion
me hodology a e discussed in Sec. 3. , Sec. 4.
and Sec. 5. co espondingly. Sec ion 6. discusses
he simula ion esul s o he p oposed JLT ansis o
and compa es he pe o mance pa ame e s wi h con-
en ional JLT. Sec ion 7. concludes he wo k.
2. Tunable Wo k Func ion
Using Bime allic S acked
Ga e
In a bime allic s acked ga e, wo di e en me als a e
g own o e he ga e dielec ic sequen ially in s acked
manne , p o iding ha bo om me al ouching he di-
elec ic should be much hinne han he op me al.
He ein, he wo k unc ion can be uned o desi ed alue
by a ying he bo om me al hickness, assuming ha
op me al is hick enough [20]. The e ec i e wo k unc-
ion alue anges be ween he wo k unc ions o wo
me als used.
The mo e accu a e explana ion o his wo k unc-
ion unabili y is based on quan um size e ec s as he
hickness o he bo om me al dec eases con inuously
[20]. The wo isola ed dis inc me als possess he same
acuum le el (E ac) bu hei espec i e Fe mi le els
(EF1 o me al-1 and EF2 o me al-2) a e di e en o
hem due o he a ying o wo k unc ion (Φm) om
me al o me al [23], as shown in Fig. 1(a) [20]. I is
assumed ha me al-1 has lowe wo k unc ion han
me al-2 (Φm1<Φm2).
Conside ing he sha p a omic p o iles and no in e -
di usion be ween he wo me als, when wo me als
a e in elec ical con ac wi h each o he , an in e ace
is o med in in ima e con ac . By i ue o chemical
equilib ium, he chemical po en ial should be cons an
h oughou he in e ace, which means ha Fe mi le el
o wo me als should be cons an a equilib ium nea
he in e ace [24].
The e o e, elec ons will low om lowe wo k unc-
ion o me al-1 o highe wo k unc ion o me al-2
and inc ease he densi y o s a es, un il Fe mi le el
ge s aligned and becomes he same o bo h me als
(Fig. 1(b)). As a esul , me al-1 is deple ed o elec ons
and me al-2 has an excess o elec ons. The concluding
space cha ge, posi i e in me al-1 and nega i e in me al-
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2, o ms an in e ace dipole laye composed o posi i e
ion co es (me al-1) and displaced ee elec ons (me al-
2) [23]. The esul ing po en ial dis ibu ion (Φ(x)) and
cha ge densi y (ρ(x)) is depic ed in Fig. 1(b).
Φm2
Φm1
E ac
EF2
EF1
Me al-1Me al-2
[Assump ion]
1) Φm1 < Φm2
2) The Me al-1 is much hinne han
Me al-2 (bulk).
Be o e con ac o ma ion
(a)
EF1
EF2
Φm1
Φme
E ac
E ac
Φm2
Me al-2 Me al-1
ρ(x)
E(x)
φ(x)
+
-
A e con ac o ma ion
d’’m1
dm1
(b)
Fig. 1: Band s uc u e o me al-me al in e ace (a) be o e con-
ac o ma ion and (b) a e con ac o ma ion [20].
Due o dipole c ea ed, he e lies an elec ic ield
(E(x)) which con i ms ha he acuum le el (E ac)
becomes sloppy in na u e [24], as shown in Fig. 1(b).
Because o ‘sc eening’ phenomena in me als, ee elec-
ons nea cha ge in dipole dis ibu ion ge pola ized
and edis ibu e o lowe he ene gy o he sys em. The
dipole wid h emains limi ed o a ew Angs oms only.
In he bulk egion, his e ec anishes no ab up ly
bu con inuously. Hence, he posi ion o E ac also
changes con inuously mo ing om in e ace o bulk
and he sepa a ion o EF(Fe mi le el) and E ac) ( ac-
uum le el) a ains cons an alue in he bulk o me al.
F om Fig. 1(b), i is obse ed ha in he case o hick
me al-1 ( hickness dm1), he elec on edis ibu ion
p ocess (elec on ans e om me al-1 o me al-2) will
cause less change in elec on densi y as compa ed o he
bulk s a e in me al-1. Thus, in hick me al-1, junc ion
dep h will be sho e and, a ga e dielec ic, alue o
wo k unc ion Φm1will appea . In he case o e y
hin me al-1 ( hickness d′′
m1), he elec on densi y will
be d as ically educed. Consequen ly, his will inc ease
junc ion dep h and a modi ied alue o wo k unc ion
will appea on he ga e dielec ic (Φm1<Φme ) [20].
Some esea che s ha e p esen ed a model o band
alignmen o he mul i-me al ga ed MOS s uc u e [8].
An analy ical model o he E ec i e Wo k Func ion
(EWF) o a bime allic s acked ga e has been p oposed
[25]. Acco ding o his,
Φme =dm1
τΦm1+1−
dm1
τΦm2,(1)
whe e 0< dm1< τ. ‘τ’ is known as he ansi ion
leng h nea he in e ace, which depends on he an-
nealing condi ions, and is he leng h o e which he en-
i e ange o unable wo k unc ion is ob ained, a ying
om wo k unc ion o he i s me al o ha o he sec-
ond me al. He e, Φme is he e ec i e wo k unc ion,
Φm1is wo k unc ion o me al-1, Φm2is wo k unc-
ion o me al-2 and dm1 is hickness o me al-1. This
model conside s no in e mixing be ween he op me al
and he ga e dielec ic and, hence, he bo om me al
also se es as a ba ie laye be ween he wo. The
analy ical a ia ion o bime allic s acked ga es such as
Ti/Au and Ni/Au has been ound o be in consis en
wi h expe imen al esul s [10].
The ela i e o de o me al laye s p o oundly a ec s
he elec ical beha io o ansis o s. I elec ons a e
dominan in he ga e s uc u e, hen he bo om me al
ha ing a lowe Φmand op me al ha ing a highe Φm
will make imp ope a angemen as du ing he edis-
ibu ion p ocess bo om will become deple ed o elec-
ons, which will ul ima ely p oduce ga e deple ion e -
ec s, hus slowing down he swi ching speed o he
ansis o . Bu i o de is e e sed ( op me al wi h
low Φmand bo om me al wi h high Φm), elec ons
will accumula e in bo om me al, hus inc easing he
popula ion densi y, which successi ely dec eases ga e
deple ion and inc eases he cu en d i e and speed o
ansis o . The ga e s uc u e wi h dominan ca ie s
as holes o ms p ope a angemen when bo om me al
has low Φmwhile he op me al has high Φm[26].
The P /Ti bime allic s ack is used in his wo k be-
cause i shows a wide EWF ange a ying om Ti
(3.9 eV) o P (5.3 eV), nea ly ∼1.4eV and his ange
is ob ained a e 300 ◦C FGA annealing wi h τ∼6nm
[27]. Due o he conside a ion o n-channel JLT he e,
P ha ing a highe Φmhas been placed a he bo om
laye .
3. De ice S uc u e &
Speci ica ion
The c oss-sec ional iews o he p oposed bime al-
lic s acked ga e-based con en ional SOI JLT
(BSG_CSJLT) and modi ied SOI JLT (BSG_MSJLT)
de ice s uc u es a e shown in Fig. 2(a) and Fig. 2(b)
espec i ely. The BSG_MSJLT has a plana SOI
s uc u e wi h sou ce, d ain, and channel doped wi h
he same n- ype impu i y and concen a ion, hus
elimina ing me allu gical junc ions like hose ha
exis in con en ional SOI-MOSFET.
In addi ion, a p- ype window is opened in he bu ied
oxide laye and is in e ical alignmen wi h he chan-
nel and ga e. The eason is ha i will help o achie e
ull deple ion and educed OFF s a e leakage by educ-
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ing he e ec i e channel hickness. The opened win-
dow has leng h 22 nm, i.e. he same as ha o he
channel. The s uc u al pa ame e s o designing he
p- ype window-based modi ied SOI JLT a e abula ed
in Tab. 1. I me i s e e encing ha s uc u al pa am-
e e s o modi ied SOI JLT a e ca e ully coo dina ed ac-
co ding o he desc ip ion in [28]. The p oposed modi-
ica ion o he ga e elec ode is implemen ed by s ack-
ing pla inum (bo om me al) and i anium ( op me al)
o e ga e oxide. Ti anium (Ti) has a ixed hickness o
30 nm while pla inum (P ) hickness is kep a iable
as i will help o une he desi ed wo k unc ion bu is
kep below he ansi ion leng h (τ∼6nm) [27]. To
analyze he impac on he pe o mance pa ame e s o
he junc ionless de ices, he wo k unc ion ange con-
side ed is om 5.0 o 5.3 eV. The speci ica ions o
BSG_CSJLT a e he same as hose o BSG_MSJLT
excep ha i does no ha e a p- ype pocke window.
P-subs a e
Bu ied Oxide
N+
Ga e oxide
D ainSou ce
Ti anium (Ti)
Pla�num (P )
N+ N+
Ga e
(a)
P-subs a e
Bu ied Oxide
N+
p- ype
window
Ga e oxide
D ainSou ce
Ti anium (Ti)
Pla�num (P )
N+ N+
Ga e
(b)
Fig. 2: Two-dimensional s uc u es o (a) BSG_CSJLT and (b)
BSG_MSJLT.
4. P ocess Flow
The p ocess low o ab ica ing he BSG_MSJLT is
included in Fig. 3. To ob ain he inal s uc u e o he
p oposed de ice, sma -cu echnique [29] o gene a e
a silicon ilm hickness o 10 nm is used and is ollowed
by he s ages as ou lined.
Low-dose Sepa a ion by Implan ed Oxygen (SIMOX
me hod) can be used o p oduce oxide on bo h sides
o he doped pocke [30] and [31]. As demons a ed in
Fig. 3, oxygen ions can be implan ed wi h app op ia e
doses and op imal implan ene gies (2.5−4.8·1017 O+
cm−2a op imized implan ene gies o 70 −140 KeV)
[31] and [32].
The o ma ion o he ga e can be ca ied ou by
sequen ially deposi ing he wo me als wi h di e en
wo k unc ions o e ga e oxide using he E-beam e ap-
o a ion me hod. La e , he ga e s ack is subjec ed o
Fo ming Gas Anneal (FGA) a e he plasma ga e e ch
[27]. The annealing empe a u e decides he ansi ion
leng h o med a he con ac o wo me als, o e which
a unable wo k unc ion ange is ob ained.
N- ype silicon
Bu ied Oxide
Subs a e
(a) n- ype doped op laye o SOI wa e .
p- ype pocke implan
N- ype silicon
Oxide
Bu ied Oxide
Subs a e
Ni ide
(b) Oxida ion, Ni ida ion and e ching ga e o
implan p- ype pocke .
Bu ied Oxide
N- ype silicon p- ype
Pocke
Subs a e
Oxide
(c) Oxide ealisa ion using low dosage SIMOX
echnique.
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Tab. 1: S uc u al pa ame e s conside ed o BSG_MSJLT de ice simula ion.
S. no. Pa ame e name Symbol Pa ame e alue Uni
1Ga e leng h Lg22 nm
2Channel hickness si 10 nm
3Ga e oxide hickness (EOT) ox 1 nm
4Bu ied oxide hickness box 80 nm
5Ga e wo k unc ion Φm5, 5.1, 5.2 and 5.3 eV
6Opened window hickness Tow 25 nm
7Ac i e egion doping (n- ype) ND1·1019 cm−3
8Opened window doping (p- ype) Now 1·1013 cm−3
9Subs a e doping (p- ype) NA1·1018 cm−3
N- ype silicon
Bu ied Oxide
Subs a e
(d) Top laye ga e oxida ion.
Subs a e
Bu ied Oxide
N- ype silicon
Me al-1 Me al-2
(e) Sequen ial deposi ion o wo dis inc ga e
me als by E-beam e apo a ion ollowed by
annealing.
Bu ied Oxide
N- ype silicon
Subs a e
Sou ce D ain
Pocke
( ) Sou ce and D ain con ac o ma ion.
Fig. 3: P oposed p ocess low o ab ica ing BSG_MSJLT.
5. Simula ion En i onmen
and Me hodology
The simula ion o de ice s uc u es and ex ac ion o
a ious pa ame e s has been ca ied ou using he SIL-
VACO ATLAS-2D de ice simula o . To ep esen ex-
ac e-enac men , a ious physical models a ailable in
ATLAS 2D de ice simula o , which a e essen ially de-
si ed o deep submic on de ice simula ion, ha e been
employed [35]. The e midi ac s a is ics is used due
o hea y doping in he channel egion. The Ene gy
Balance T anspo model is enabled using hc e in he
model s a emen , which se s he solu ion o elec on
and hole balance. In ene gy balance model: Pois-
son’s equa ion, ca ie con inui y equa ions, and en-
e gy balance equa ions o mobile ca ie s a e sol ed
sel -consis en ly. The sel -hea ing equa ion is com-
bined wi h he a o emen ioned equa ions o conside
he hea gene a ion wi hin he de ice. Selbe he ’s
impac ioniza ion model is se using an impac selb
s a emen . The la . emp model is also ini ialized o
accoun o solu ion o la ice ene gy balance equa ion.
The equi ed he mal bounda y condi ion is included
by de ining a he mal con ac a bo om o he de ice
ixed a 300 K using he he mcon ac s a emen . Va i-
ous o he physical models included a e bgn o conside
bandgap na owing e ec s, bb .s d model o analyze
he e ec s o band- o-band unneling, c o inco po-
a e mobili y dependence on channel doping and bo h
ans e se and longi udinal elec ic ields, s h o in-
clude Shockley-Read- Hall ecombina ion o he ixed
mino i y ca ie li e ime, and auge model o conside
Auge ecombina ions.
The nume ical me hod chosen is block new on o
calib a e he de ice solu ions o gi en bias ol ages.
To app o e he SILVACO ATLAS ool, he simula ion
se up is calib a ed wi h simula ion esul s o [28] which
a e al eady calib a ed wi h expe imen al esul s o [33].
6. Resul s and Discussion
The expe imen al and analy ical a ia ions o e ec-
i e wo k unc ion (Φme ) wi h changing hickness
(dm1) o bo om me al-1 pla inum (P ) a e plo ed in
Fig. 4, conside ing he equi alen MOS capaci o s uc-
u e (included in Fig. 4). He e, he ansi ion leng h
(τ) is conside ed o be 6 nm, ob ained a 300 ◦C FGA
(Fo ming Gas Anneal) condi ion [27]. I can be seen
ha he e ec i e wo k unc ion anges om 3.9 eV (Ti
only) o 5.3 eV (P only) o P hickness a ia ion
0< dm1<6nm [27]. Thus, a wide ange o un-
able wo k unc ion (∼1.4eV) can be achie ed wi h
he P /Ti bime allic s acked ga e. The pe cen age di -
e ence be ween expe imen al and analy ical EWF is
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ound o be a maximum o 6.68 %, which is e y sa is-
ac o y (less han 10 %).
0 1 2 3 4 5 6
3,8
4,0
4,2
4,4
4,6
4,8
5,0
5,2
5,4
P only
Ti only
P /Ti [27]
P /Ti analy ical
P Thickness, dm1 (nm)
E ec i e wo k unc ion, ϕme (eV)
Ti
P
SiO2
Si
Fig. 4: The expe imen al and analy ical a ia ion o e ec i e
wo k unc ion (Φme ) wi h pla inum me al hickness
(dm1).
The ole o ga e me al wo k unc ion in ope a ing
junc ionless de ices is e y c i ical. The de ice pe o -
mance is al e ed by he ga e me al wo k unc ion, since
he la band ol age a ies linea ly wi h wo k unc ion.
No mally, JLT is an ON de ice, so he channel should
be ully deple ed o s op conduc ion in he OFF s a e.
Wi h inc easing ga e me al wo k unc ion, he h esh-
old shi s owa ds posi i e alue in n-channel JLT.
Figu e 5 shows he ans e cha ac e is ics (ID-VGS)
o SOI JLTs plo ed on loga i hmic scale. The OFF
s a e is assumed o be a VGS = 0 V and ON s a e a
VGS =VDS = 1 V. The OFF-s a e cu en (IOF F )
dec eases wi h inc easing wo k unc ion because in-
c eased Φm esul s in he educ ion o minimum po-
en ial in he channel egion, hus p o iding be e su-
pe ision in OFF s a e. This e ec i ely educes s a ic
powe dissipa ion inside he de ice. As obse ed om
Fig. 5, he BSG_MSJLT shows lowe leakage han he
BSG_CSJLT, due o be e deple ion achie ed in chan-
nel egion owing o educed channel hickness in he
BSG_MSJLT. Table 2 clea ly depic s his leakage cu -
en educ ion imp o emen o BSG_MSJLT a each
wo k unc ion alue. The basic weakness o SOI JLT
is ela i ely low ION /IOF F a io and can be co ec ed
by g ading he d ain doping le el [34].
In he ON s a e, a educ ion in ON cu en (ION )
is obse ed a highe wo k unc ion alues as he
p esence o elec ons in he channel is no eased a
highe wo k unc ion. Imp o ed ION is ob ained in
BSG_MSJLT (Fig. 5(b)) o e BSG_CSJLT (Fig. 5(a))
because o enhanced elec on mobili y due o mi iga ed
la ice hea ing. Hence, he combined e ec o lowe
IOF F and highe ION inc eases he ION /IOF F a io o
BSG_MSJLT mo e han ha o BSG_CSJLT, as p e-
sen ed in Table 2. Thus, he ela i e swi ching powe
will always be g ea e han 1. The e ec o highe
Φmis mo e p onounced in IOF F han in ION , hence,
ION /IOF F a io also enhances a highe wo k unc ion.
This imp o emen na u e is consis en wi h esul s o
[2].
0,0 0,2 0,4 0,6 0,8 1,0 1,2 1,4 1,6
2×10-4
4×10-4
6×10-4
8×10-4
10-3
1,2×10-3
1,4×10-3
ϕm
VDS=1 V
Ga e ol age, VGS (V)
5.0 eV
5.1 eV
5.2 eV
5.3 eV
D ain cu en , ID (A∙µm-1)
(a)
0,0 0,2 0,4 0,6 0,8 1,0 1,2 1,4 1,6
2×10-4
4×10-4
6×10-4
8×10-4
10-3
1,2×10-3
1,4×10-3
VDS=1 V
Ga e ol age, VGS (V)
5.0 eV
5.1 eV
5.2 eV
5.3 eV ϕm
D ain cu en , ID (A∙µm-1)
(b)
Fig. 5: D ain Cu en (IDS ) a ia ion agains ga e ol age
(VGS) on loga i hmic scale o (a) BSG_CSJLT and
(b) BSG_MSJLT.
Figu e 6 depic s ansconduc ance (gm) a ia ion
agains ga e ol age (VGS) o di e en ga e me al wo k
unc ions a a d ain ol age o 1 V. The ansconduc-
ance (in Eq. (2)) beha io s a di e en wo k unc ions
a e e y much simila o each o he . The only di e -
ence is ha he ga e ol age a which maximum gm
appea s shi s owa ds a posi i e ol age alue wi h
inc easing wo k unc ion. This ga e ol age shi is ex-
plained by he linea dependence o la band ol age
on he wo k unc ion. F om Fig. 6, i is e iden ha in
compa ison o BSG_CSJLT (Fig. 6(a)), an imp o e-
men o 11.7 % is achie ed in he maximum gm o
©2022 ADVANCES IN ELECTRICAL AND ELECTRONIC ENGINEERING 78
THEORETICAL AND APPLIED ELECTRICAL ENGINEERING VOLUME: 20 |NUMBER: 1 |2022 |MARCH
BSG_MSJLT (Fig. 6(b)). This e ec o wo k unc ion
on he maximum gmo bo h de ices is abula ed in
Tab. 2.
0,0 0,2 0,4 0,6 0,8 1,0 1,2 1,4 1,6
0,3
0,4
0,5
0,6
0,7
ϕm
VDS=1 V
gm=∂ID/∂VGS
T ansconduc ance, gm (mS)
Ga e ol age, VGS (V)
5.0 eV
5.1 eV
5.2 eV
5.3 eV
(a)
0,0 0,2 0,4 0,6 0,8 1,0 1,2 1,4 1,6
0,3
0,4
0,5
0,6
0,7
ϕm
VDS=1 V
gm=∂ID/∂VGS
T ansconduc ance, gm (mS)
Ga e ol age, VGS (V)
5.0 eV
5.1 eV
5.2 eV
5.3 eV
(b)
Fig. 6: T ansconduc ance (gm) a ia ion agains ga e ol age
(VGS) o (a) BSG_CSJLT and (b) BSG_MSJLT.
gm=∂ID
∂VGS
.(2)
Figu e 7 shows ou pu cha ac e is ics (ID-VDS ) a
di e en ga e wo k unc ions o bo h de ices. The
ga e ol age is a ied om 0.5 V o 2 V wi h a s ep
o 0.5 V. Highe wo k unc ion esul s in a dec eased
ON-s a e cu en in he sa u a ion egion. A di e en
ga e ol ages, he BSG_MSJLT (Fig. 7(b)) is d i -
ing la ge amoun o cu en han he BSG_CSJLT
(Fig. 7(a)). This pe o mance imp o emen is e-
lec ed a each wo k unc ion alue, hus, making
he BSG_MSJLT mo e sui able o d i ing a la ge
amoun o cu en e en a smalle d ain ol age (VDS )
han he BSG_CSJLT.
0,0 0,2 0,4 0,6 0,8 1,0 1,2 1,4 1,6
0,0
2,0×10-4
4,0×10-4
6,0×10-4
8,0×10-4
1,0×10-3
1,2×10-3
1,4×10-3
1,6×10-3
ϕm
VGS= 2 V, ΔVGS= -0.5 V
D ain ol age, VDS (V)
5.0 eV
5.1 eV
5.2 eV
5.3 eV
D ain cu en , ID (A∙µm-1)
(a)
0,0 0,2 0,4 0,6 0,8 1,0 1,2 1,4 1,6
0,0
2,0×10-4
4,0×10-4
6,0×10-4
8,0×10-4
1,0×10-3
1,2×10-3
1,4×10-3
1,6×10-3
1,8×10-3
ϕm
VGS= 2 V, ΔVGS= -0.5 V
D ain ol age, VDS (V)
5.0 eV
5.1 eV
5.2 eV
5.3 eV
D ain cu en , ID (A∙µm-1)
(b)
Fig. 7: D ain cu en (IDS ) a ia ion agains d ain ol age
(VDS) o (a) BSG_CSJLT and (b) BSG_MSJLT.
Figu e 8 shows he plo s o ga e- o-sou ce capaci-
ance (Cgs) and ga e- o-d ain capaci ance (Cgd) mea-
su ed agains he ga e ol age a di e en wo k unc-
ions. I is ob ained by pe o ming small signal analysis
wi h VDS = 1 V and equency o 100 MHz, a e dc
analysis. The capaci ances inc ease wi h inc ease in
ga e ol age. No imp o emen was ob ained in he ca-
paci ance alues wi h inc easing ga e me al wo k unc-
ion, only he posi ion o occu ence has shi ed o-
wa ds posi i e ga e ol age due o change in la band
ol age. In compa ison, i is obse ed ha a each ga e
wo k unc ion alue, Cgd is educed o BSG_MSJLT
(Fig. 8(b)) o e ha o BSG_CSJLT (Fig. 8(a)), bu
BSG_MSJLT shows inc eased Cgs o e BSG_CSJLT.
This is only due o he addi ional capaci i e coupling
e ec a ising be ween he ga e and sou ce e minal due
o he p-n junc ion o med in he e ical di ec ion o
he n- ype channel and p- ype window.
©2022 ADVANCES IN ELECTRICAL AND ELECTRONIC ENGINEERING 79
THEORETICAL AND APPLIED ELECTRICAL ENGINEERING VOLUME: 20 |NUMBER: 1 |2022 |MARCH
0,0 0,2 0,4 0,6 0,8 1,0 1,2 1,4 1,6
0,24
0,26
0,28
0,30
0,32
0,34
0,36
ϕm
ϕm
VDS=1 V
5.0 eV
5.1 eV
5.2 eV
5.3 eV
Ga e ol age, VGS (V)
Ga e-sou ce capaci ance, Cgs ( F/μm )
0,05
0,10
0,15
0,20
0,25
0,30
Ga e-d ain capaci ance, Cgd ( F/μm )
(a)
0,0 0,2 0,4 0,6 0,8 1,0 1,2 1,4 1,6
0,28
0,30
0,32
0,34
0,36
ϕm
ϕm
VDS=1 V
5.0 eV
5.1 eV
5.2 eV
5.3 eV
Ga e ol age, VGS (V)
Ga e-sou ce capaci ance, Cgs ( F/μm )
0,05
0,10
0,15
0,20
0,25
Ga e-d ain capaci ance, Cgd ( F/μm )
(b)
Fig. 8: Ga e- o-sou ce capaci ance (Cgs) and ga e- o-d ain ca-
paci ance (Cgd) measu ed agains he ga e ol age
(VGS) o (a) BSG_CSJLT and (b) BSG_MSJLT.
Figu e 9 shows he e ec o di e en ga e wo k unc-
ions on cu o equency o ansi ion equency ( T)
o junc ionless ansis o s. I is he equency a which
he de ice e lec s uni y gain. Hence, highe Tis al-
ways desi able o sui o RF applica ion. Also, he po-
si ion o plo has shi ed o mo e posi i e ga e ol age
wi h inc easing wo k unc ion due o inc eased de ice
h eshold.
As illus a ed in Fig. 9(b), BSG_MSJLT shows
a maximum To 279.51 GHz, which is app oxi-
ma ely 2.21 % imp o emen o e he maximum To
273.45 GHz shown by BSG_CSJLT (see Fig. 9(a) and
Tab. 2). The inc ease in Cgs was compensa ed by in-
c eased gmand dec eased Cgd and BSG_MSJLT s ill
manages o p oduce highe T.
T=gm
2π(Cgs +Cgd).(3)
0,0 0,2 0,4 0,6 0,8 1,0 1,2 1,4 1,6
75
100
125
150
175
200
225
250
275
ϕm
VDS=1 V
T = gm/(2π(Cgs+Cgd))
Cu o equency, T (GHz)
Ga e ol age, VGS (V)
5.0 eV
5.1 eV
5.2 eV
5.3 eV
(a)
0,0 0,2 0,4 0,6 0,8 1,0 1,2 1,4 1,6
100
125
150
175
200
225
250
275
ϕm
VDS=1 V
T = gm/(2π(Cgs+Cgd))
Cu o equency, T (GHz)
Ga e ol age, VGS (V)
5.0 eV
5.1 eV
5.2 eV
5.3 eV
(b)
Fig. 9: Cu o equency ( T) a ia ion agains ga e ol age
(VGS) o (a) BSG_CSJLT and (b) BSG_MSJLT.
Figu e 10 shows Global De ice Tempe a u e (GDT)
o bo h de ices changing wi h d ain ol age, wi h a y-
ing wo k unc ion. Global empe a u e o de ice in-
c eases wi h inc easing d ain ol age as elec on mo e-
men in he channel ises wi h VDS due o which mo e
he mal hea is ans e ed om ca ie o he la ice.
The GDT has dec eased conside ably wi h inc easing
wo k unc ion alue. The highes ise in empe a u e
in BSG_MSJLT (Fig. 10(b)) a VDS = 1.5V and a
Φm= 5.0eV is s ill less han 500 K, while GDT ises
up o 600 K in BSG_CSJLT (Fig. 10(a)). Thus, i is
e iden ha BSG_MSJLT g ea ly educes he de ice
he mal hea ing issue. This educ ion in empe a u e
is a ained due o he inse ion o ligh ly doped p- ype
window in BSG_MSJLT which acili a es dissipa ion
o hea on inc easing d ain ol age.
In Tab. 2, he p oposed de ice BSG_MSJLT shows
ON/OFF a io be e han BSG_CSJLT wi h open
window doping (Now = 1 ·1013 cm−3) bu i is no ap-
©2022 ADVANCES IN ELECTRICAL AND ELECTRONIC ENGINEERING 80
THEORETICAL AND APPLIED ELECTRICAL ENGINEERING VOLUME: 20 |NUMBER: 1 |2022 |MARCH
Tab. 2: Pe o mance compa isons o BSG_CSJLT, BSG_MSJLT and R_DGJLFET [6] in wo k unc ion ange om 5.0 eV o
5.3 eV.
S. No. Pa ame e s
Wo k unc ion
5.0 eV 5.1 eV
BSG_
CSJLT
BSG_
MSJLT
(Now = 1
·1013
cm−3)
BSG_
MSJLT
(Now = 1
·1020
cm−3)
R_DG
JLFET
[6]
BSG_
CSJLT
BSG_
MSJLT
(Now = 1
·1013
cm−3)
BSG_
MSJLT
(Now = 1
·1020
cm−3)
R_DG
JLFET
[6]
1IOF F (mA) 0.472 0.453 8.41e−10 1.1e−90.416 0.404 1.5e−11 3e−11
2ION (mA) 1.098 1.152 0.387 1.09 1.046 1.087 0.221 0.859
3ION /IOF F 2.32 2.54 7.15e89.8e82.51 2.69 1.4e10 2.7e10
4gm(max) (mS) 0.666 0.744 1.83 ∼2.20.666 0.744 1.83 ∼2.2
5 T(max) (GHz) 273.45 279.51 751.03 - 273.45 279.51 751.03 -
S. No. Pa ame e s
Wo k unc ion
5.2 eV 5.3 eV
BSG_
CSJLT
BSG_
MSJLT
(Now = 1
·1013
cm−3)
BSG_
MSJLT
(Now = 1
·1020
cm−3)
R_DG
JLFET
[6]
BSG_
CSJLT
BSG_
MSJLT
(Now = 1
·1013
cm−3)
BSG_
MSJLT
(Now = 1
·1020
cm−3)
R_DG
JLFET
[6]
1IOF F (mA) 0.371 0.367 2.69e−11 8.9e−13 0.337 0.335 5.17e−12 2.9e−14
2ION (mA) 0.988 1.02 0.058 0.608 0.928 0.943 0.009 0.365
3ION /IOF F 2.66 2.77 2.1e96.7e11 2.75 2.81 4.6e91.2e13
4gm(max) (mS) 0.666 0.744 1.83 ∼2.20.666 0.744 1.83 ∼2.2
5 T(max) (GHz) 273.45 279.51 751.03 - 273.45 279.51 751.03 -
p eciable due o e y low alue. Howe e , by inc easing
he doping le el o open window o Now = 1·1013 cm−3
[36], he ON/OFF a io can be inc eased by mani olds
e en g ea e han 106, hus, main aining he eliabili y
o he de ice.
Table 3 summa izes he RF and he mal pe -
o mance compa ison be ween BSG_MSJLT and
BSG_CSJLT. Va ious alues o analog/RF pa ame e s
a e calcula ed o di e en wo k unc ions in he ON
s a e (a VGS =VDS = 1 V) using small signal ac
analysis a 100 MHz.
0,0 0,2 0,4 0,6 0,8 1,0 1,2 1,4 1,6
300
350
400
450
500
550
600
ϕm
Global de ice empe u e (K)
D ain ol age, VDS (V)
5.0 eV
5.1 eV
5.2 eV
5.3 eV
VGS=1 V
(a)
0,0 0,2 0,4 0,6 0,8 1,0 1,2 1,4 1,6
300
350
400
450
500
ϕm
VGS=1 V
Global de ice empe a u e (K)
D ain ol age, VDS (V)
5.0 eV
5.1 eV
5.2 eV
5.3 eV
(b)
Fig. 10: Global de ice empe a u e a ia ion agains d ain ol -
age (VDS) o (a) BSG_CSJLT and (b) BSG_MSJLT.
AV=gm
gd,(4)
TFP =gm
IDS · T,(5)
IGD =VDD
ION ·Cgg.(6)
The ansconduc ance (gm) alue is obse ed o in-
c ease wi h inc easing wo k unc ion in he ON s a e o
bo h de ices bu gmis always highe o BSG_MSJLT
©2022 ADVANCES IN ELECTRICAL AND ELECTRONIC ENGINEERING 81