GaN HEMT WITH AlGaN BACK-BARRIER FOR HIGH POWER MILLIMETRE WAVE APPLICATIONS

William, STATIC AND DYNAMIC CHARACTERISTICS OF Lg 50 nm InAlN/AlN/GaN HEMT WITH AlGaN BACK-BARRIER FOR HIGH POWER MILLIMETRE WAVE APPLICATIONS, Journal of Science: Advanced Materials and[r]

STATIC AND DYNAMIC CHARACTERISTICS OF Lg 50 nm InAlN/AlN/GaN HEMT WITH AlGaN BACK-BARRIER FOR HIGH POWER MILLIMETRE WAVE APPLICATIONS

P Murugapandiyan, Assistant Professor, S Ravimaran, Professor, J William, Professor

PII: S2468-2179(17)30006-0

DOI: 10.1016/j.jsamd.2017.08.004

Reference: JSAMD 118

To appear in: Journal of Science: Advanced Materials and Devices

Received Date: 21 January 2017 Revised Date: 21 July 2017 Accepted Date: August 2017

Please cite this article as: P Murugapandiyan, S Ravimaran, J William, STATIC AND DYNAMIC CHARACTERISTICS OF Lg 50 nm InAlN/AlN/GaN HEMT WITH AlGaN BACK-BARRIER FOR HIGH POWER MILLIMETRE WAVE APPLICATIONS, Journal of Science: Advanced Materials and Devices (2017), doi: 10.1016/j.jsamd.2017.08.004

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STATIC AND DYNAMIC CHARACTERISTICS OF Lg 50nm InAlN/AlN/GaN HEMT WITH AlGaN BACK-BARRIER FOR HIGH POWER MILLIMETRE WAVE APPLICATIONS

P.Murugapandiyan1, S.Ravimaran2, J.William3

1Assistant Professor, Department of Electronics and Communication Engineering, Agnel Institute of Technology and Design, Goa-India

2Professor, Department of Electrical and Computer Science, M.A.M College of Engineering, Trichy,Tamilnadu,

3Professor, Department of Electronics and Communication Engineering, M.A.M College of Engineering and Technology, Trichy,Tamilnadu, India

Email: murugavlsi@gmail.com

Authors

P.Murugapandiyan has received his B.E in Electronics and Communication Engineering

from Anna University , Chennai, Tamil Nadu, India in 2008 and he received Master of Engineering in VLSI Design from Anna University, Chennai, Tamil Nadu, India in the year 2013 He is pursuing Ph.D at Anna University, Chennai, Tamilnadu- India Now he is working as Assistant Professor in the Department of Electronics and Communication Engineering, Agnel Institute of Technology and Design, Goa-India His research focuses on modelling and simulation of III–N compound semiconductor materials and devices for future high speed with high power MMIC applications

Dr.S.Ravimaran , Principal and Professor in Computer Science and Electrical Engineering

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Transaction Management Using Surrogate Objects in Distributed Mobile Systems fromAnna University Chennai, India in 2013 His research interests are High speed wireless Communication Networks and wide band attenna design for MMIC RF applications

Dr.J.William, Principal and Professor in Electronics and Communication Engineering

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STATIC AND DYNAMIC CHARACTERISTICS OF Lg 50 nm

InAlN/AlN/GaN HEMT WITH AlGaN BACK-BARRIER FOR HIGH POWER MILLIMETRE WAVE APPLICATIONS

Abstract

In this paper, a novel 50 nm recessed T-gate AlN spacer based InAlN/GaN HEMT with AlGaN back-barrier is designed The static and dynamic characteristics of the proposed device structure are investigated using Synopsys TCAD tool The other device features are

heavily doped source/drain region, Al2O3 passivated device surface which are helped the

device to suppress the parasitic resistances and capacitances of the transistor for enhancing the microwave characteristics The proposed InAlN/GaN HEMT exhibits the

sheet carrier density (ns) of 1.9x1013 cm-2, drain current density (Ids) of 2.1 A/mm,

transconductance (gm) of 800 mS/mm, 40 V breakdown voltage (VBR), current gain cut-off

frequency (ft) of 221 GHz and power gain cut-off frequency (fmax) of 290 GHz The

superior static and dynamic characteristics of InAlN/GaN HEMT obtained, undoubtedly places the device at the forefront for high power millimetre wave applications

Keywords

HEMT, 2DEG, static and dynamic characteristics, cut-off frequency, back-barrier

1.Introduction

Recently the lattice matched InAlN/GaN heterojunction high electron mobility transistors (HEMTS) are of great interest for high power switching and RF applications because of their high breakdown voltage, high current density and thermal stability The limitations of AlGaN/GaN HEMT have been reached now in particular for the bottom part of the mm-wave spectrum (30-300 GHz) Furthermore the unavoidable strain caused by the lattice mismatch between GaN and AlGaN limits the Al contents of the barrier to about 30% and therefore the

2DEG density to ~1013 cm-2 As a consequence, the maximum current density is limited to

A/mm The presence of strain has been identified as a source of failure for these devices (5, 6)

Lattice matched InAlN/GaN HEMTs presents several advantages with respect to AlGaN/GaN They allow for a more efficient downscaling of the transistor dimensions,

making easier to achieve the cut-off frequencies (ft and fmax) more than 200 GHz (8)

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HEMTs, are suffering from leakage currents and consequently low breakdown voltages reported (12), as well as strong short channel effects (13) The ohmic contacts were characterized to reduce the contact resistance of ~0.3 Ω.mm (13).Devices for high temperature operation on the other hand from high buffer leakage which strongly degrades the operating temperature of HEMT InAlN/GaN HEMTs Provide a better carrier confinement in the 2DEG than conventional AlGaN/GaN based HEMT due to larger spontaneous polarization between the barrier and channel (6) To reduce the alloy disorder scattering at the InalN/GaN interface, a very thin AlN spacer layer is placed between them which improves the 2DEG density

In this work we have proposed a novel 50 nm recessed T-gate InAlN/GaN HEMT with

AlGaN back-barrier The heavily doped source/drain region associated with Al2O3 passivated

device surface reduces the parasitic capacitances (Cgd and Cgs) and T-gate structure provides

low gate resistances (Rg) while maintaining large gate area (high mobility) A 1nm wide band

gap (6.02 eV) AlN spacer layer along with AlGaN back-barrier provides the effective confinement of electrons in the 2DEG region Moreover, the buffer leakage current is mitigated by the back-barrier and the gate leakage current is majorly suppressed by AlN spacer layer The symmetric gate position and back-barrier are helped the device to achieve higher breakdown voltage, which is essential key factor for high power applications

2 InAlN/GaN HEMT device structure and Band gap Diagram:

The vertical cross section of InAlN/AlN/GaN/AlGaN HEMT device structure is depicted in Fig.1 The device consists of inch SiC substrate to achieve good thermal stability, 1450 nm

Fe doped GaN buffer layer which isolate the channel from the substrate defects, 3.5 nm

Al0.07Ga0.93N back-barrier layer which helps to confine the more electron in the channel due

its effective conduction band notch at the interface with GaN channel and also it contributed

for higher carrier mobility in the 2DEG (~1500 Cm2/V-s) Moreover, the buffer leakage

current is effectively mitigated by the Al0.07Ga0.93N back-barrier The channel region is

defined by 30 nm GaN and 10 nm In0.17Al0.83N is used as barrier layer A very thin nm AlN

spacer layer is placed between the barrier and channel which improves the electron mobility in the 2DEG by reducing the interface roughness and alloy disorder scattering at the interface of InAlN/GaN The induced spontaneous and piezoelectric polarization electric field provides

an improved sheet charge carrier density of 1.9x1013 cm-2 in the 2DEG and also due to the

higher band gap of the barrier limits the gate leakage current and reduces the short channel effects in the device The source and drain regions are formed by heavily doped GaN (50 nm)

with Si in the order of ~ 7x1020 cm-3 to minimize the contact resistances The source and

drain ohmic contacts were designed by using Ti/Pt/Au metal stack and T-shaped recessed gate (6nm recess depth) is formed with the head size of 450 nm, stem height of 140 nm with 50 nm footprint is designed, which liftoff wide cross sectional gate area with smaller gate length and Schottky contact is formed by Ni/Pt/Au metal stack The reduction in the gate to drain space can causes the high electric field in the gate-source region which results in high

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distance are kept at 30 nm and 80 nm respectively to maintain a low electrostatic field in the gate-drain space channel region while maintaining enhanced breakdown voltage In order to reduce the parasitic capacitances of the device, finally the device surface is fully passivated

by 10 nm Al2O3 layer which greatly helped for achieving higher cut-off frequencies Usually

Si3N4 is the commonly used passivation layer to avoid the current collapses, but the larger

thickness of passivation layer is needed, which will increases the gate capacitance

particularly gate-drain capacitance (Cgd) In this model a 10 nm Al2O3 is used as passivation

layer which assists to unfasten the dispersion effects and it provides a root to good transport property in the 2DEG

Figure.1 Vertical Cross-sectional view of InAlN/AlN/GaN/AlGaN heterostructure

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The Polarization charge distribution and conduction band offset diagram of InAlN/AlN/GaN/InGaN is depicted in Fig.2 (a) and (b) respectively The InAlN/GaN

heterojunction benefits the high 2DEG density (~1013 cm-2) without doping and high electron

mobility (~2000 cm2/V-s) because of the large conduction band discontinuity between the

InAlN/GaN The high 2DEG density is achieved by the large spontaneous and piezoelectric polarization field inside the InAlN layer Due to induced piezoelectric polarization between AlGaN and GaN there will be a sharp raised potential barrier is formed at the back of 2DEG channel Such a sharp notch helps to confine the electron in better manner in the channel region and also it mitigates the buffer leakage current, which also contributed for improving the breakdown voltage of the transistor A very thin nm wide band gap (6.01 eV) AlN spacer is placed between barrier and channel to offer large effective conduction band offset and also it helps to reduce the gate leakage current

3 Result and discussion

In this article, we have proposed and investigated the static and dynamic characteristics of a novel 50 nm x 20 µm T-gate InAlN/GaN HEMT with AlGaN back-barrier Fig.3 depicts the

sheet charge carrier density (ns) dependence on barrier thickness (tbarrier) for AlGaN/InAlN

barrier materials A 10 nm InAlN barrier layer achieved a sheet carrier density of 1.9 x1013

cm-2 which is comparatively higher than with the AlGaN barrier layer and the measured

mobility in the 2DEG is 1450 cm-2/V-s

Fig.4 shows the V–I characteristics of Lg = 50 nm and W = 20 µm InAlN/AlN/GaN HEMT

The simulation result gives a supreme current density of 2.1 A/mm at Vgs = 2V and the

device is pinched off perfectly at Vgs = -2V This higher current density is achieved mainly

because of the enhanced mobility with greater sheet charge carrier density in 2DEG channel The lattice-matched InAlN/GaN with nm SiN spacer provides effective conduction band offset and it reduces strain induced surface defects at the interface Moreover, the AlGaN notch helps to provide better confinement of charge carriers in the channel and also it

suppressed the buffer leakage current in the device The device on resistance (Ron) is the

source of power dissipation when the transistor working in linear region, the extracted very

low Ron of the proposed device from the drain characteristics is 0.3 Ω.mm

The breakdown voltage (VBR) of the device is the most essential parameter for high power RF

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Fig.6.shows the transconductance variation with the gate bias voltage The maximum

transconductance of the device is measured from the plot is 800 mS/mm at Vgs = -1 V and the

associated drain voltage is V The extracted threshold voltage of the device from the transfer characteristics shown in Fig.7 is -1.5 V

The short channel effects (SCEs) are the major problems in nanometer regime gate length

devices, the drain current variation with gate-source bias for different Vds is displayed in

Fig.8 (semilog scale) A small threshold voltage (Vth) shift of proposed HEMT device result

of good aspect ratio (Lg/d) maintained by recessed gate structure, where d is the distance from

gate to channel From the log-scale plot, a very small 63 mV/V drain induced barrier

lowering (DIBL) and 80 mV/dec subthreshold swing (SS) at Vds = V is extracted from the

subthreshold characteristics shown in Fig.8 Moreover, the improved Ion/Ioff ratio of ~105 is

achieved, which is important factor for high speed switching applications The gate leakage

current (Ig) depends on the band gap of the barrier and channel materials The wide band gap

of nm AlN spacer layer effectively suppressed the gate leakage current for such a smaller

gate length device in the order of 1x10-13 A/mm displaying in Fig.9 at Vds = 2V

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Figure.4 V-I Characteristics of Lg = 50 nm and w = 20 µm InAlN/GaN HEMT

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Figure.6 Dependences of gm on the gate bias of Lg = 50 nm and w = 20 µm InAlN/GaN

HEMT

Figure.7 Dependences of Id on the gate bias of Lg = 50 nm and w = 20 µm InAlN/GaN

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Figure.8.Subthreshold characteristics of Lg = 50 nm and w = 20 µm InAlN/GaN HEMT

Figure.9 Gate leakage current verses gate–source bias of Lg = 50 nm and w = 20 µm

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Figure.10 ft and fmax variation with Vgs of Lg = 50 nm and w = 20 µm InAlN/GaN HEMT

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The expression for ft and fmax are as follows;

Current gain Cut-off frequency:

 = /

    ./  

(1)

Power gain cut-off frequency:

 = !"

#  !"

(2)

Where the source resistance $% = &'

() + &  +.,-

( ) and drain resistance $/ = & '

() +

& +.,.0

( ) $1 and $%2 are the contact resistance and channel sheet resistance respectively

345 and 356 are gate to source and gate to drain spacing respectively is the width of the

gate $ is the gate access resistance and 8/% represents drain conductance The gate to drain

capacitance is 9/ is an essential parameter for high-frequency operation of the device A 10

nm Al2O3 passivated device surface reduces the overall gate capacitance in our proposed

device model

The simulation of current gain cut-off frequency (ft) and power gain cut-off frequency

(fmax) of Lg = 50 nm InAlN/GaN HEMT is depicted in Fig.10 For fixed Vds = V, the HEMT

device exhibited a peak ft/fmax of 221/290 GHz at Vgs = -1 V The ft/fmax dependence of gate

length (Lg) of proposed HEMT is shown in Fig.11 The obtained results are best cut-off

frequencies of 50 nm gate length GaN-based HEMT with a high current density of 2.1 A/mm

simultaneously maintaining VBR of 40 V and low gate leakage current among any materials

so far from author’s knowledge This ft/fmax is achieved by drastic reduction in the contacts

resistances (Rd and Rs), gate resistance (Rg) and parasitic capacitances (Cgs and Cgd) of the

device mainly because of heavily doped (n++ GaN) source / drain regions has direct contacts with the channel, combined with drain /source access region, passivated device surface, and a

T-gate structure The features of recessed T-gate structure are to minimize the Rg and

enhancing the mobility by providing large gate area Moreover, the minimum short channel

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Table.1 Recent Research Progress in GaN-based HEMTs for High Power RF applications

Reference Lg in nm Idmax(A/mm) ft/fmax

(GHz)

VBR

(V)

SCEs

[24],2009 150 0.8 47/81 - -

[25],2010 130 1.9 93/127 - -

[26],2014 80 1.1 114/230 95 -

[27],2013 27 348/340 10.7 -

[28],2015 110 1.25 60/101 21 -

[29],2016 70 1.65 162/176 - -

[10],2013 30 1.9 400/33 - DIBL 240 mV/V

[30],2011 30 1.57 245/13 - -

[13],2011 30 2.18 205/220 - -

[16],2010 30 1.8 300/33 16 -

[31],2011 60 2.1 210/55 50 DIBL 530 mV/V

[32],2013 75 0.8 170/210 - DIBL 63 mV/V

[33],2010 160 1.19 79/113.8 23.6 -

[3],2012 30 1.5 370/30 - DIBL 220 mV/V

[34],2011 70 1.2 115/310 - -

[35],2011 500 1.5 26.5/17 - -

[36],2009 120 2.4 132/17.5 24 -

[37],2013 100 1.65 80/200 - -

[38],2015 80 1.13 115/150 - -

[39],2015 140 1.2 65/100 34 -

This work 50 2.1 221/290 40 DIBL 63 mV/V,

SS 80 mV/dec

Conclusion

The static and dynamic characteristics of a novel 50 nm recessed T-gate InAlN/GaN HEMT with AlGaN back-barrier has been studied by using Synopsys TCAD tool The

proposed device features are heavily doped (n++ GaN) source/drain regions with Al2O3

passivated device surface, which are helped to reduce the contact resistances and parasitic

capacitances of the device to uplift the microwave characteristics of the HEMTs Lg of 50 nm

HEMT shows a ft/fmax of 221/290 GHz The peak drain current density of 2.1 A/mm is

achieved by offering effective conduction band offset by using InAlN barrier material associated with back-barrier by enhancing the sheet charge carrier density in 2DEG region

1.9Χ1013 cm-2 with higher carrier mobility of 1450 cm2/V.s A 40 V off-state breakdown

voltage (VBR) is achieved by keeping the large gate to drain separation than gate to source

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The authors acknowledge the Nanoelectron Device Laboratory of Electronics and Communication Engineering Department at M.A.M College of Engineering, Trichy-India for providing all facility to carry out this research work

References

[1] D Marti, S Tirelli, V Teppati, L Lugani, J.-F Carlin, M.Malinverni, N Grandjean, and C R Bolognesi, 94-GHz large-signal operation of AlInN/GaN high-electron-mobility transistors on silicon with regrown ohmic contacts, IEEE Electron Device Lett (2015)

[2] G Perillat-Merceroz, G Cosendey, J.-F Carlin, R Butté, N Grandjean, Intrinsic degradation mechanism of nearly lattice-matched InAlN layers grown on GaN substrates, J Appl Phys (2013) [3] Y Yue, Z Hu, J Guo, B Sensale-Rodriguez, G Li, R Wang, F Faria,T Fang, B Song, X Gao, S

Guo, T Kosel, G Snider, P Fay, D Jena, H Xing, InAlN/AlN/GaN HEMTs with regrown ohmic contacts and fT of 370 GHz, IEEE Electron Device Lett 33 (2012) 988-990 https://doi.org/ 10.1109/LED.2012.2196751

[4] J Guo, G Li, F Faria, Y Cao, R Wang, J Verma, X Gao, S Guo, E Beam, A Ketterson, M Schuette, P Saunier,M.Wistey, D Jena, H Xing, MBE-regrown ohmics in InAlN HEMTs with a regrowth interface resistance of 0.05 -¢mm, IEEE Electron Device Lett (2012)

[5] S.Y Parka, C Florescaa, U Chowdhuryb, J L Jimenezb, C Leeb, E Beamb, P Saunierb,T Balistrerib, M J Kim, Physical degradation of GaN HEMT devices under high drain bias reliability testing, Microelectron Rel (2009)

[6] E Zanoni,M.Meneghini, A Chini, D.Marcon, G.Meneghesso, AlGaN/GaN-based HEMTs failure physics and reliability:Mechanisms affecting gate edge and Schottky junction, IEEE Trans Electron Devices (2013)

[7] Nanjo T, Motoya T, Imai A, Enhancement of drain current by an AlN spacer layer insertion in AlGaN/GaN high-electron-mobility transistors with Si-ion-implanted source/drain contacts, Japanese J Appl Phys (2011) https://doi.org/ 10.1143/JJAP.50.06410

[8] S Liu, S Yang, Z Tang, Q Jiang, C Liu, M Wang, K J Chen, Al2O3/AlN/GaN MOS-channel-HEMTs with an AlN interfacial layer, IEEE Electron Device Lett 35 (2014) 723-725 https://doi.org/ 10.1109/LED.2014.2322379

[9] F.Medjdoub, J.-F Carlin, M Gonschorek, E Feltin,M A Py, D Ducatteau, C Gaquiere,N Grandjean, , E Kohn, Can InAlN/GaN be an alternative to high power / hightemperature AlGaN/GaN devices?, IEDM Tech Dig (2006) 673

[10] Yuanzheng Yue., Zongyang Hu., Jia Guo1., Berardi Sensale-Rodriguez, Guowang Li., Ultrascaled InAlN/GaN High Electron Mobility Transistors with Cutoff Frequency of 400GHz, Japanese Journal of Applied Physics 52 (2013) http://dx.doi.org/10.7567/JJAP.52.08JN14

[11] D Maier, M Alomari, N Grandjean, J.-F Carlin, M.-A Diforte-Poisson, C Dua,A Chuvilin, D Troadec, C Gaquière, U Kaiser, S L Delage, E Kohn, Testing the temperature limits of GaN-based HEMT devices, IEEE Trans Device Mater Rel (2010)

[12] J Kuzmík, A Kostopoulos, G Konstantinidis, J.-F Carlin, A Georgakilas, D Pogany, InAlN/GaN HEMTs: A first insight into technological optimization, IEEE Trans Electron Devices 55 (2008) 937 [13]S Tirelli, D Marti, H Sun, A.R Alt, J.-F Carlin, N Grandjean, C.R Bolognesi, Fully passivated

AlInN/GaN HEMTs with ft /fMAX of 205/220 GHz, IEEE Electron Device Lett 32 (2011) 1364 [14] H.-C Chiu, J.-H Wu, C.-W Yang, F.-H Huang, H.-L Kao, Low-frequency noise in

enhancement-mode GaN MOS-HEMTs by using Stacked Al2O3/Ga2O3/Gd2O3 gate dielectric, IEEE Electron Device Lett 33 (2012) 958-960 https://doi.org/10.1109/LED.2012.2194980

MAN

USCR

IPT

ACCE

PTED

[16] D S Lee, X Gao, S Guo, D Kopp, P Fay, T Palacios, 300-GHz InAlN/GaN HEMTs with InGaN back barrier, IEEE Electron Device Lett 32 (2011) 1525–1527 https://doi.org/ 10.1109/LED.2011.2164613

[17] O Ambacher, J Majewski, C Miskys, A Link, M Hermann, M Eickhoff, M Stutzmann, F Bernardini, V Fiorentini, V Tilak, B Schaff, L F Eastman, Pyroelectric properties of Al(In)GaN/GaN hetero- and quantum well structures, J Phys Condens Matter (2002)

[18] Wood C, Jena D, Polarization Effects in Semiconductors, Springer-Verlag, New York, NY, USA, 2008

[19] Khandelwal S., Fjeldly T.A., A physics-based analytical model for 2DEG charge density in AlGaN/GaN HEMT device, Solid-state Electronics 76 (2012) 60–66

[20] Y.-F Wu, A Saxler, M Moore, R P Smith, S Sheppard, P M Chavarkar, T Wisleder, U K Mishra, P Parikh, 30-W/mm GaN HEMTs by field plate optimization, IEEE Electron Device Lett 25 (2004) 117–119 https://doi.org/10.1109/LED.2003.822667

[21] Xia L, Hanson A, Boles T, Jin D, On reverse gate leakage current of GaN high electron mobility transistors on silicon substrate, Appl.Phys Lett (2013) https://doi.org/10.1063/1.4798257

[22] Sourabh Khandelwal, T.A.Fjeldly, A Physics based compact model of I-V and C-V characteristics in AlGaN/GaN HEMT devices, Solid state electronics (2012) https://doi.org/10.1016/j.sse.2012.05.054 [23] Parvesh Gangwani, sujata Pandey, Subhasis Haldar, Mridula gupta, Polarization dependent analysis of

AlGaN/GaN HEMT for high power applications, Solid State Electronics (2006) https://doi.org/ 10.1016/j.sse.2006.11.002

[24]T Palacios, AlGaN/GaN High Electron Mobility Transistors With InGaN Back-Barriers, IEEE Electron Device Lett 27 (2005) https://doi.org/ 10.1109/LED.2005.860882

[25]Nidhi, fT and fMAX of 47 and 81 GHz, Respectively, on N-Polar GaN/AlN MIS-HEMT, IEEE Electron Device Lett 30 (2009) 599 https://doi.org/10.1109/LED.2009.2020305

[26]K Shinohara, 220 GHz fT and 400 GHz fmax in 40 nm GaN DH-HEMTs with Re-grown Ohmic, IEDM Tech Dig (2010) 672

[27]Brian P Downey, David J Meyer, D Scott Katzer, Jason A Roussos, Ming Pan, Xiang Gao, SiNx/InAlN/AlN/GaN MIS-HEMTs With 10.8 THz·V Johnson Figure of Merit, IEEE Electron Device Lett 35 (2014) https://doi.org/10.1109/LED.2014.2313023

[28]Michael L, Gate-Recessed Integrated E/D GaN HEMT Technology With fT / fmax >300 GHz, IEEE Electron Device Lett 34 (2013) https://doi.org/10.1109/LED.2013.2257657

[29]Han Tingting, 70-nm-gated InAlN/GaN HEMTs grown on SiC substrate with fT=fmax > 160 GHz, J.Semiconductors 37 (2016)

[30]Dong Seup Lee, 245-GHz InAlN/GaN HEMTs With Oxygen Plasma Treatment, IEEE Electron Device Lett 32 (2011) https://doi.org/10.1109/LED.2011.2132751

[31]Ronghua Wang, 210-GHz InAlN/GaN HEMTs With Dielectric-Free Passivation, IEEE Electron Device Lett 32 (2011) https://doi.org/10.1109/LED.2011.2147753

[32]D.M Geum, S.H Shin, M.S Kim, J.H Jang, 75 nm T-shaped gate for In0.17Al0.83N/GaN HEMTs with minimal short-channel effect, Electronics Letters 49 (2013) 1536–1537

[33]A Crespo, High-Power Ka-Band Performance of AlInN/GaN HEMT With 9.8-nm-Thin Barrier, IEEE Electron Device Lett 31 (2010) https://doi.org/10.1109/LED.2009.2034875

[34]D.J Denninghof, N-polar GaN HEMTs with/max> 300 GHz using high-aspect-ratio T-gate design, IEDM Tech Dig (2011)

[35]Nidhi, Self-Aligned Technology for N-Polar GaN/Al(Ga)N MIS-HEMTs, IEEE Electron Device Letters, 32 (2011) https://doi.org/10.1109/LED.2010.2086427

[36]Nidhi, N-polar GaN-based highly scaled self-aligned MIS-HEMTs with state-of-the-art fT.LG product of 16.8 GHz-µm, IEDM Tech Dig (2009)

MAN

USCR

IPT

ACCE

PTED

IEEE Electron Device Letters (2015) https://doi.org/10.1109/LED.2014.2379664

10.1016/j.jsamd.2017.08.004 ...

AlGaN /GaN HEMT for high power applications, Solid State Electronics (2006) https://doi.org/ 10.1016/j.sse.2006.11.002

[24]T Palacios, AlGaN /GaN High Electron Mobility Transistors With. .. T-shaped gate for In0.17Al0.83N /GaN HEMTs with minimal short-channel effect, Electronics Letters 49 (2013) 1536–1537

[33]A Crespo, High- Power Ka-Band Performance of AlInN /GaN HEMT With 9.8-nm-Thin... T-gate InAlN /GaN HEMT with AlGaN back-barrier has been studied by using Synopsys TCAD tool The

proposed device features are heavily doped (n++ GaN) source/drain regions with Al2O3