Transcript Kickoff Meeting Expectations

Mechanisms of Ionization-Induced Carrier
Transport and Collection
in Next-Generation III-V Structures
Dale McMorrow
Radiation Effects Section
Naval Research Laboratory
Washington, DC
UNCLASSIFIED
Outline
• Objectives/Overview
• Motivation
• III-V Technology Overview
• Radiation Effects in III-V Technologies
• NextGen III-V Research Program
• Technology Transfer
UNCLASSIFIED
Description of the Effort
• ABCS: Antimonide-Based Compound Semiconductors
• To investigate, using both theory and experiment, the basic
mechanisms of ionization-induced carrier deposition,
transport, and collection in next-generation antimonide-based
III-V compound semiconductor structures and materials
• This is a collaborative effort between the Naval Research
Laboratory and Vanderbilt University
UNCLASSIFIED
Status of the Effort
• Significant ongoing ABCS technology development
• DARPA ABCS Program (2001-2006)
• DARPA ISIS Program (2007-present)
• Intel CRADA
• Very little is understood about the performance of ABCS
technologies in hostile environments
• Experimental and theoretical databases are minimal
• NRL has unique access to Sb-based technology, and has
developed the experimental approaches necessary to
address their response to ionizing radiation
• Vanderbilt is ideally suited to take the lead on the
theory/computational part of this effort
UNCLASSIFIED
III-V Semiconductor Material Systems
2.8
0.45
AlP
ZnSe
0.50
AlAs
AlAs
ZnTe
0.60
AlSb
AlSb
1.6
0.80
InP
InP
GaAs
GaAs
1.00
1.2
Si
In
0.8
1.30
GaSb
GaSb
Ga
As
2.00
Ge
InAs
InAs
0.4
5.00
InSb
0
5.4
5.6
5.8
6.0
6.2
Lattice Constant (Å)
Lattice
Constant, m
UNCLASSIFIED
6.4
Wavelength (m)
Energy Gap
(eV) eV
Gap,
Energy
GaP
2.0
Wavelength, m
2.4
III-V Semiconductor Material Systems
UNCLASSIFIED
Motivations: ABCS Electronics
High-speed, low-power consumption electronics
are needed for light-weight power supplies,
extension of battery lifetimes, and high data rate
transmission
• Low-noise receivers
• space-based sensing and communications
• portable communications
• micro-air-vehicles (MAVs)
UNCLASSIFIED
Motivations: ABCS Electronics
• High-speed logic circuits
•
•
•
•
high-speed onboard processing
communications, data transmission
potential for lowest power-delay product
integration with RTDs for enhanced functionality
and low-voltage operation
• InP HEMTs presently hold the record current gain
cutoff frequency for any three-terminal device
UNCLASSIFIED
Motivations: ABCS Electronics
• Sb-based electronics exhibit:
•
•
•
•
•
•
High electron mobility
High electron velocity
High sheet charge density
Large conduction band offset
<0.5 V operation / low power dissipation
Low noise
• Digital circuits with speeds >100 GHz are
anticipated
UNCLASSIFIED
ABCS Technology Development
• The NRL Microwave Technology Branch is a world leader in
the growth, fabrication and characterization of Sb-based
HEMTs, p-channel HFETs, and HBTs.
• DARPA ABCS Program (2001-2006):
• NRL teamed with Northrop-Grumman Space Technology (NGST,
formerly TRW) to develop next-generation high-speed, lowpower HEMT and HBT technology using antimonide
heterostructures.
• At the inception of the ABCS program, NRL had been in the
forefront of the development of antimonide HEMT technology for
more than seven years.
• NRL’s superior material growth and device processing
capabilities let to a record high cutoff frequency fT of 250 GHz,
and a 90 GHz fT at a record low voltage of 0.1 volts
• NRL growth and processing technology for antimonide HEMTs
transferred to NGST via CRADA in FY03.
UNCLASSIFIED
ABCS Technology Development
• DARPA ABCS Program Major Milestones:
• demonstration of an antimonide HEMT with a record maximum
frequency of oscillation (fmax = 275 GHz)
• Demonstration of an order of magnitude less power
consumption than HEMTs based on competitive semiconductor
material systems
• The first antimonide-based X-band and W-band MMICs with
state-of-the-art low-power performance
Ref: J. Vac. Sci. Technol. B, 17 (3), May 1999
UNCLASSIFIED
ABCS Technology Development
• DARPA Integrated Structure is Sensor (ISIS) Program
• NRL is again teamed with NGST
• Continue to develop next-generation high-speed, low-power Sbbased HEMT technology.
• Intel CRADA
• NRL is also currently teamed with Intel, via a Cooperative
Research and Development Agreement (CRADA), to develop
advanced p-channel Sb HFETs for use in high-speed
complementary logic applications
UNCLASSIFIED
ABCS Technology: InAs HEMT
AlSb
InAs 20 Å
In0.4Al0.6As 40 Å
AlSb 12 Å
InAs(Si) 12 Å
AlSb 125 Å
AlSb 30 Å
InAs subchannel 42 Å
AlSb 500 Å
Al 0.7Ga0.3Sb 0.3 m
0.5
Energy (eV)
InAs 100 Å
1.0
E0’
E1
E0
0.0
-0.5
AlSb 1.7 m
InAs
-1.0
SI GaAs substrate
6.1 Å Lattice Spacing
0
50
100
150
In0.4Al0.6As InAs(Si)
200
250
300
350
400
450
500
Distance (Å)
• 1.7 m AlSb buffer layer on GaAs (SI) substrate: accommodates 8% lattice mismatch
• InSb-like interfaces: high electron mobility
• Modulation doping in thin InAs(Si) layer: sheet charge densities of 1-4 x 1012/cm2
• Large InAs/InAlAs valence band offset: lower leakage current from holes
• InAs sub-channel reduces impact ionization: higher frequency operation
UNCLASSIFIED
III-V Semiconductor Material Systems
2.8
0.45
AlP
ZnSe
0.50
AlAs
AlAs
ZnTe
0.60
AlSb
AlSb
1.6
0.80
InP
InP
GaAs
GaAs
1.00
1.2
Si
In
0.8
1.30
GaSb
GaSb
Ga
As
2.00
Ge
InAs
InAs
0.4
5.00
InSb
0
5.4
5.6
5.8
6.0
6.2
Lattice Constant (Å)
Lattice
Constant, m
UNCLASSIFIED
6.4
Wavelength (m)
Energy Gap
(eV) eV
Gap,
Energy
GaP
2.0
Wavelength, m
2.4
ABCS Technology: InAsSb HEMT
InAs
In0.4Al 0.6As
In0.2Al0.8Sb
20 Å
InAs0.7Sb0.3
150 Å
In0.2Al0.8Sb
75 Å
40 Å
150 Å
In0.69Al0.31As0.41Sb0.59
1.0 m
AlSb
GaAs substrate
1.5 m
InAsSb HEMT has attractive material properties
and unique design flexibility enabling improved
high-speed, low-power performance:
InAlSb
InAlSb
InAsSb
Type I Band Alignment
• Higher electron mobility and velocity for
higher speed.
• Type I band alignment for lower leakage
and lower noise figure.
6.2 Å Lattice Spacing
• Reach peak velocity at lower electric field
for lower power consumption.
• Complete structure is stable in air for
increased stability.
UNCLASSIFIED
Radiation Effects in III-V FETs
• III-V FETs typically are tolerant to high levels of ionizing
radiation
• Lack of native oxides
• Dominated by displacement damage (DD) effects
• III-V FET-based technologies typically are extremely
susceptible to single-event effects
• A primary goal of this program is to develop an
understanding of the basic mechanisms of carrier
transport and collection that lead to this SEE
susceptibility
UNCLASSIFIED
Rad Effects: TID/DD in III-V FETs
• Recent work at NRL demonstrates that 6.1 Å ABCS
technology is more tolerant than either GaAs or InPbased technologies
• Due to strong carrier confinement
in heterostructure wells
• Weaver, et al., “High tolerance of
InAs/AlSb high-electron-mobility
transistors”, Appl. Phys. Lett, 87,
173501 (2005).
UNCLASSIFIED
Rad Effects: SEE in III-V FETs
• GaAs MESFETs and HFETs; Extensive work in 1990s:
• Experiment and Simulation (NRL and others)
• Charge collection and enhancement mechanisms fairly well
understood
• InP HEMTs: Limited experimental and simulation work
• Experimental data similar to that of GaAs devices (NRL)
• Simulation results inadequate but reveal significant differences
• ABCS Devices:
• HI and pulsed laser data on 6.1 Å technology (NRL)
• No simulation results on 6.1 Å technology
• No data/simulation on 6.2 Å or 6.3 Å technologies
UNCLASSIFIED
Rad Effects: CC in GaAs HFETs
0
6
(b) 3 MeV  Particle
100 fC Deposited Charge
-2
Drain Signal, mV
VG = -1.0 V
-6
VG = 0.0 V
-8
-10
VG = 0.15 V
-12
Collected Charge, pC
5
-4
4
Charge Enhancement
3
2
1
-14
(a)
-16
0
100
200
300
400
500
600
100 fC
0
700
Time, ps
-1.0
-0.8
-0.6
-0.4
Gate Bias, V
UNCLASSIFIED
-0.2
0.0
0.2
Rad Effects: CC in GaAs HFETs
0.0
S
S
D
G
G
D
0.6
Depth, m
0.5
0.4
1.0
0.6
1E12
1.2
3E11
1.5
0.8
1.0
(b) t < 0
(a) t < 0
2.0
0.0
0.5
0.5
Depth, m
0.7
1.0 1E14
1.0
3E16
1.5
(c) t = 32 ps
2.0
0.0
0.5
(d) t = 32 ps
1E15
1.0
1.3
1.2
1E16
1.5
2.0
0.0
Position, m
0.5
1.0
Position, m
UNCLASSIFIED
1.5
2.0
Rad Effects: CC in GaAs HFETs
• 10X - 60X charge enhancement observed
• HI and laser excitation
• Associated with S-D current (from power supply)
• Barrier lowering at source-substrate barrier
• device turned “on”
• Associated with charge deposited below active
region
• 1 m to 2 m most effective
• Current pathway from source, deep through
substrate, to drain
UNCLASSIFIED
Hole Density
Electron Density
S
Rad
Effects: CC in InP
HEMTs
G
G
G
D
S
G
D
• Experiment
• Device simulation
t<0 ps
t<0 ps
• Mechanisms are significantly different from GaAs
400 ps
400ps
ps
50
cutline
cutline
Rad Effects: CC in InP HEMTs
0
Current, MA/cm
2
t < 0 ps
t = 400 ps
1e18
(600 ps)
1e8 (600
ps)
-5
Carrier Injection
and S-D Current
Confined to
InGaAs Channel
-10
InAlAs
-15
0.00
InGaAs
0.05
InAlAs
0.10
Depth in Device, m
UNCLASSIFIED
0.15
18
holes
16
14
Excess Hole
Density in
InAlAs buffer:
12
8
0.0
electrons
appx. 1015 cm-3
InP
10
InGaAs
InAlAs
Log(Carrier Concentration), cm
-3
Rad Effects: CC in InP HEMTs
0.2
0.4
0.6
Position, m
UNCLASSIFIED
0.8
1.0
Depth, m
0.5
0.4
Rad Effects: Bulk vs. HEMTs
1.0
0.6
1E12
1.2
3E11
1.5
0.8
(b) t < 0
(a) t < 0
Bulk (GaAs MESFET)
2.0
1.0
InP HEMT
0.0
0.5
0.5
Depth, m
0.7
400 ps
1.0
1E14
1.0
3E16
1.5
1E16
(c) t = 32 ps
2.0
0.0
0.5
(d) t = 32 ps
1E15
1.0
1.3
1.2
1.5
2.0
0.0
Position, m
0.5
1.0
Position, m
UNCLASSIFIED
1.5
2.0
Rad Effects: AlSb/InAs HEMTs
(a)
40
GaAs MESFET
50
InP HEMT
VD = 1.1 V
VG = -0.40 V
40
0
InP HEMT
-20
0
20
40
60
80
100
(b)
1
2 = 73 ns
3 = 4.8 s
GaAs MESFET
0.1
Drain Voltage, mV
Drain Voltage, mV
20
30
InAs HEMT
VD = 0.45 V
VG = -0.50 V
20
10
0
-25
2 = 42 ns
0.01
0
25
50
75
100
125
Time, ns
3 = 440 ns
InP HEMT
Fig. 5. Comparison of drain charge-collection transients
measured for an InGaAs/InAlAs HEMT and an AlSb/InAs
Time, ns
HEMT for 37 MeV·cm2/mg LET(GaAs) ions (278 MeV 79Br
at 45° incidence) for worst-case bias conditions of VD = 1.1 V;
Fig. 4. Comparison of heavy-ion induced drain chargeVG = -0.4 V and VD = 0.45 V and VG = -0.5 V, respectively.
collection transients measured for a GaAs MESFET and an
UNCLASSIFIED
2
0
250
500
750
1000
Technical Approach
• OBJECTIVE: To investigate, using both theory and
experiment, the basic mechanisms of ionizationinduced carrier deposition, transport, and collection
in next-generation antimonide-based III-V compound
semiconductor structures and materials.
• APPROACH:
• Experiment: measurement of charge collection transients
in 6.1 Å and 6.2 Å ABCS test structures
• Theory: develop a theoretical description to describe the
highly non-equilibrium state induced in heterosructure
devices by ionizing radiation; use the experimental data to
validate and calibrate the theory
UNCLASSIFIED
Technical Approach
• Experimental Approach (NRL):
•
•
•
•
Test structure selection
Packaging in high-bandwidth packages
High-bandwidth transient measurement
Statistical analysis of ion-induced transients
• Theoretical Approach (VU):
• Develop a theoretical description
• Evaluate capabilities of various commercial codes and
determine suitability
• Use the experimental data to validate and calibrate the
theory
• Identify the basic mechanisms of carrier transport and
collection that are responsible for shaping the data
UNCLASSIFIED
Technical Approach
(a)
1.0
50-GHz
Bias-T
Drain (45 fC)
0.5
12-GHz
Scope
source
drain
50
0.0
Current (mA)
Heavy-ion
Irradiation
drain
bias
Body (45 fC)
-0.5
(b)
1.0
Drain (75fC)
50
HF package
0.5
0.0
Body (12 fC)
-0.5
-0.5
0.0
0.5
1.0
1.5
2.0
Fig. 8. Schematic diagram of the experimental set-up used
Time (ns)
for measurement of high-bandwidth transients from
semiconductor structures. The particular configuration Fig. 9. Drain and body charge-collection transients
illustrated is for the simultaneous measurement of both measured in coincidence for two different ion strikes for a
• drain
High-bandwidth
(12-20
GHz),
transient
measurement
70 nm partially-depleted
SOI transistor
with body
the
and body electrodes on
an SOI test
structuresingle-shot
contacts. VD = 1.0 V; all other terminals grounded. 808
with the 12 GHz bandwidth single-shot oscilloscope. The MeV 78Kr at 0° incidence.
• Permits
direct
measurement
entire
temporal profile
is measured
for both channels of
for ion-induced transients for single
every ion
ion strike.
strikes for the first time
UNCLASSIFIED
Technical Approach
• Theoretical Approach (VU):
• One graduate student assigned to this project
(Sandeepan DasGupta)
• Vanderbilt will provide access to its Advanced
Computing center for Research and Education
(ACCRE), which houses their Beowulf cluster
supercomputer
UNCLASSIFIED
Progress
• Initial test structures selected
• Mounted in high-bandwidth packages
• Tested for dc operational characteristics
• Heavy-Ion test scheduled for June
• Vanderbilt student (Sandeepan DasGupta) is
getting started
• Reading literature
• Evaluating available commercial codes
• Asking questions
UNCLASSIFIED
Key Personnel
• NRL Solid State Electronics Branch
• Radiation Effects Branch (McMorrow, Warner)
• NRL Microwave Technology Branch
• Brad Boos
• Vanderbilt/ISDE
• Robert Reed
• Ron Schrimpf
• Grad student
UNCLASSIFIED
Technology Transfer
• NRL ABCS technology development program
• ISDE Engineering
• Collaborative R&D, e.g. NRL/Vanderbilt
• DoD vendor relationships
• NASA Goddard
• Through students
UNCLASSIFIED