Large-Signal Performance of AlInN/GaN-on

Transcription

Session:
Millimeter-Wave PAs for 5G and Beyond
Large-Signal Performance of
AlInN/GaN-on-Silicon HEMTs at 94 GHz
C.R. Bolognesi
Millimeter-Wave Electronics Group (MWE)
ETH-Zürich, Gloriastrasse 35, Zürich 8092, Switzerland
http://www.mwe.ee.ethz.ch/
September 15, 2014
PA Symposium 2014 / San Diego CA
1
Collaborators
 ETHZ
– S. Tirelli
– D. Marti
– Dr. V. Teppati
September 15, 2014
 EPFL
–
–
–
–
–
–
L. Lugani
M. Malinverni
J.-F. Carlin
E. Feltin
M.A. Py
Prof. N. Grandjean
2
Considerations / Outline
 AlInN/GaN Materials
– Lattice-Matching to GaN
– Reduced Surface Depletion vs. AlGaN/GaN
 Requirements for mm-Wave HEMTs
–
–
–
–
–
Gate-Channel Spacing / Source-Drain Separation
Short-Channel Effects (SCEs)
Series Resistances / Ohmic Contacts (Annealed vs. Regrown)
Large-Signal on Silicon (W-Band)
PDK and W-Band Prototype on Silicon
September 15, 2014
3
Lattice Matching (Al0.83In0.17N:GaN)
EG~ 4.7 eV
In: 17%
September 15, 2014
4
Materials
Lattice Matching: A Reliability Enhancer (?)
G. Meneghesso et al.
Park et al. (TRIQUINT)
Cumulative Strain (Mismatch + Piezo) Correlated to Device Degradation
September 15, 2014
5
Materials
AlInN/GaN High Temperature Stability (1000⁰C)
F. Medjdoub et al., IEDM 2006
AlInN/GaN HEMTs Survive 1000⁰C
Temperatures
(Potential for High-T Electronics)
September 15, 2014
6
Materials
Substrate Choices
Silicon:
1,030 cm2/Vs @ 2×1013 /cm2
300 Ω/ (–17% mismatch)
SiC:
1,300 cm2/Vs @ 2.4×1013 /cm2
205 Ω/ (–3.5% mismatch)
Excellent Mobility in 2DEG:
Dislocations are screened by the high
carrier density
Appl. Phys. Lett. 89, 062106 (2006)
September 15, 2014
7
Materials
Surface Depletion: InP vs. GaAs HEMT Analogy
Reduced Gate-to-Channel Distance
Theoretical Advantages:
 Higher GM
 Higher Current Drive, IDMAX
 Improved Aspect Ratio LG/d
 Weaker Short-Channel Effects
 Textbook Approach to High-Speed
All Recent Record GaN HEMTs:
 Thin Barriers (AlInN or AlN)
 Higher Channel Sheet Density
Proc. IEEE, p.494 (1992)
September 15, 2014
8
Requirements: Reduced S/D Spacing
The Original Studies of RS and RD Effects on
GaN HEMT Bandwidth…
(Essentially, re-work Hughes/Tasker pHEMT
analysis)
September 15, 2014
9
–
–
–
–
Large-Signal on Silicon (94 GHz)
September 15, 2014
10
Ohmic Contacts (1)
Metallization:
Ti / Al / Mo / Au
Yields
RC ≈ 0.3 to 1 Ω∙mm
(strong variability)
September 15, 2014
Requirements:
• Good Morphology
• Low Contact Resistance
Rapid Thermal Annealing
T ~ 850ºC
11
Regrown Contacts (2)
Drain
Regrown:
Channel
Source
RSD
RC
RSD
2DEG
RC
Beneficial for Short LSD Spacings (RSD < RC)
Better Reproducibility with Respect to Annealed Ohmics
(Best Example: Shinohara et al., HRL)
September 15, 2014
12
Regrown Contacts (3)
Annealed
W = 50 µm LSD = 1 µm
Gain (dB)
50
40
H21
30
U
fMAX(U) = 230 GHz
fMAX(U) = 250 GHz
fT= 170 GHz
fT= 128 GHz
20 MSG
10
0
1
September 15, 2014
Regrown
VDS= 10 V
VGS= -1 V
10
VDS= 9 V
VGS= -1.1 V
100 1
Frequency (GHz)
10
100
13
–
–
–
–
Large-Signal on Silicon (94 GHz / W-Band)
September 15, 2014
14
Large-Signal Operation
Class A
ID,MAX
ID
apse
Large-signal
current coll
IDC
Small-signal
IDC
VKnee short-channel eff.
VKnee
VDS
September 15, 2014
BVOFF
+ Output Impedance Matched for max POUT
+ Current Collapse and SCEs Limit POUT
15
(On Silicon)
d = 7.5 nm, LG = 50 nm, LSD = 2 µm on HR-Silicon.
Improved Buffer / Channel Design. Regrown Contacts.
800
2.0
Vds=5 V
700
600
gm (mS/mm)
1.6
IDS (A/mm)
1.6
1.2
0.8
1.2
500
400
0.8
300
0.4
200
0.4
IDS (A/mm)
VGS= 2 to -4 V in -2 V steps
100
0.0
0
2
4
6
VDS (V)
DC Characteristics
+ GM > 650 mS/mm
+ Adequate Pinch-Off
September 15, 2014
8
10
0
-4
-3
-2
-1
VGS (V)
0
1
0.0
2
+ Good Transport: µ = 1200 cm2/Vs (300 Ω/sq)
+ Back-Barrier not Implemented
16
Power gain (Gp), output power
(Pout), power added efficiency
(PAE) at VGS = – 1.2 V and VDS = 9
V at 94 GHz for a 50 nm gatelength
device, with source-drain spacing of
2 µm, source-gate spacing 0.5 µm
and a total gate width of 100 µm
d = 7.5 nm, LG = 50 nm, LSD = 2 µm on HR-Silicon.
Improved Back-Buffer / Channel Design. Regrown Contacts
24
fMAX(U) = 232 GHz
fT = 141 GHz
30
20
VDS = 6.5 V
VGS = -1.3 V
10
1
10
Frequency (GHz)
PAE
Pout
Gp
20
16
12
8
12
PAE (%)
Gp (dB) , Pout (dBm)
LG = 50 nm
40
Gain (dB)
16
8
4
4
100
0
0
6
9
12
15
18
Pin,del (dBm)
94 GHz Initial Results
1 W/mm / PAE = 12% / GP = 4 dB @ PIN,Del = 16 dBm
(Better than 1 W/mm Result on SiC)
September 15, 2014
17
@ 94 GHz on SiC
d = 6 nm, LG = 100 nm, LSD = 1 µm on SiC.
No Back-Barrier. Regrown Contacts.
8 24
1.51 W/mm
POUT (dBm), PAE (%)
21
8
1.69 W/mm
7 21
7
18
6 18
6
15
5 15
5
12
1 W/mm, 8.5% 4 12
4
9
3 9
6
2 6
3
1 3
0
6
GP
POUT
PAE
3
2
1.2 W/mm, 5%
0 0
8 10 12 14 16 18 20 22
6
GP (dB)
24
1
0
8 10 12 14 16 18 20 22
PIN,DEL (dBm)
PIN,DEL (dBm)
(VGS, VDS) = (-1.2, 11) V
(VGS, VDS) = (-1.3, 15) V
Best results at 94 GHz for AlInN-based HEMTs on SiC
September 15, 2014
18
PDK and PA Prototype Development (1)
Large-Signal Model (Angelov)
Harmonic Balance Simulation
in ADS) vs. Load Pull
Measurement at 94 GHz for a
2x50um AlInN/GaN on Si
device.
Process Design Kit PDK
Scalable Large-Signal Model
(Gate Width & Fingers)
September 15, 2014
19
MMIC Process based on Grounded Coplanar Waveguides
Ground
Signal Ground
Via
Ground
September 15, 2014
20
3 Stage PA Simulation
(2x50 um Devices for all Stages)
2 x 50um
AlInN HEMT
Input
Network
2 x 50um
AlInN HEMT
2 x 50um
AlInN HEMT
Inter-Stage
Network
Inter-Stage
Network
2 x 50um
AlInN HEMT
Inter-Stage
Network
2 x 50um
AlInN HEMT
2 x 50um
AlInN HEMT
Output
Network
2 x 50um
AlInN HEMT
Input, Inter-Stage and Output Networks Simulated with
Lumped Elements (Full Characterization and Modeling of
Passives Elements are Underway)
September 15, 2014
21
• 3 Stage PA Simulation Results
• Additional Losses of 1 to 3 dB Expected with Lossy
Interconnects in Implementation.
September 15, 2014
22
Conclusions
 Excellent Progress with mm-Wave AlInN/GaN HEMTs
– Process Integration Developments (Back-Barrier / Regrown Ohmics)
 GaN-on-Silicon is mm-Wave Ready
 Impressive POUT at 94 GHz on Silicon (1.3 W/mm)
 Improved Large-Signal Stability
 PDK and PA Prototype Development on Silicon
– W-Band Gain Block Feasible: 15 dB at W-Band
– Refinements Required
September 15, 2014
23

Large-Signal Performance of AlInN/GaN-on

Transcription

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