Erik Lind ([email protected]) · Heterostructure Field Effect Transistor / High Electron...
13
High-Speed Devices, 2011 2011-01-13 1 Introduction, High Speed Devices 2011 Erik Lind ([email protected] ) Course consists of: •30 h Lectures (H322, and Fys B – check schedule) •8h Excercises •2x2h+4h Lab Excercises (2 Computer simulations, 4 RF measurment lab) • Written report on device performance (2-3 pages), w/ 10 min oral presentation • Written Exam (15/12) Course Material – Fundamentals of III-V Devices, William Liu ppt-slides from lectures Course Homepage - http://wwwgu.ftf.lth.se/courses/fff115.html Download and bring slides to the lectures!!
Transcript of Erik Lind ([email protected]) · Heterostructure Field Effect Transistor / High Electron...
High-Speed Devices, 2011
2011-01-13 1Introduction, High Speed Devices 2011
Erik Lind ([email protected])
Course consists of:•30 h Lectures (H322, and Fys B – check schedule)•8h Excercises•2x2h+4h Lab Excercises (2 Computer simulations, 4 RF measurment lab)• Written report on device performance (2-3 pages), w/ 10 min oral presentation• Written Exam (15/12)
Course Material – Fundamentals of III-V Devices, William Liuppt-slides from lectures
Course Homepage - http://wwwgu.ftf.lth.se/courses/fff115.htmlDownload and bring slides to the lectures!!
My Background
2011-01-13 2Introduction, High Speed Devices 2011
•M.Sc. in Engineering Physics (2000)•Ph.D. in Solid State Physics 2004
•Post Doc at UC Santa Barbara, 2006-2007
•Assistant Professor (Forskarassistent) @ Solid State Physics 2007-
•Ph.D.: Tunneling devices, (Quantum dots, SiGe Esaki tunnel diodes, and Resonant Tunneling diodes/transistors)
•Post Doc: High-speed InP/InGaAs DHBTs (500+ GHz ft, fmax)
•Currently: InAs nanowire transistors, UWB sources, III-V MOSFETs
Locations
2011-01-13 3
k-space
My office: C367
EIT
Introduction, High Speed Devices 2011
Course Contents
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•Review of basic semiconductor physics (no real derivations), Carrier statistics, Transport & Continuity Equations, Electrostatics (2)
•Heterojunctions, especially pN-heterojunctions (2)
•Heterobipolar transistors (HBTs) – DC and AC operation (4)
•Heterostructure Field Effect Transistors (HFET, HEMT) – DC and AC operation (3)
•Device Scaling Laws (HBTs and HFETs) (1)
• Ballistic FETs (1)• Resonant Tunneling Diodes (1)
Course Goals
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Material Science:Bandgaps, Heterojunctions,
Mobilities
Semiconductor Physics:Electrostatics
Electron Transport Eqs.Electron Dynamic Eqs.
Device Physics :Heterojunctions
Heterojunction BipolarTransistor
Field Effect Transistors
High Freuency Behaviour:Functionallity
DesignScaling laws
Project
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• Illustrate state-of-the-art device performance
• Litterature Study on different type of devices
• Present your finding to the other students, 10 min or so.
Laborations
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• 2 Computer labs: Simulate HBT and FET using TCAD program (2x2 h).
• 1 Device analysis lab. Measure high frequency parameters, extract certaindevice parameters. Lab report, gives bonus points on exam (1x4 h).
Heterostructure Bipolar Transistor (HBT)
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InP Emitter (n+)
InGaAs Base (p++)
InP Collector (n)
Ec
Ev
Ec Ec
Ev
•Similar to ordinary BJT•Uses large bandgap emitter•Very high base-doping –> Low base resistance!
• pN junctions• Diffusion Across the base• Quasi Fermi Levels• Drift in the collector
Heterostructure Field Effect Transistor / High Electron Mobility Transistor (HFET/HEMT)
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•Similar to ordinary MOSFET•Utilizes a large bandgap as isolation• Moves mobile channel charge awayfrom oxide interface & any doping• Very high mobility!!
• Drift current, velocity saturationand ballistic transport
VgsSource
x
Vds
Wide bandgap w/ doping
Wide bandgap w/o doping
Narrow Bandgap channel w/o doping
Ef
GateContact
Wide Bandgap
Small bandgap channelHigh mobility!
Physical realization
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62.5 nm
HFETHBT
Who to connect between:•Material science•Semiconductor Physics•Models for circuit design!
2 minute exercise - linearization
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vdsids=f(vds)
DS
DSd
DSDSDS
DSDSDS
v
ig
iIi
vVv
xxdx
xdfxfxxf
)()(
)()(
Important device metrics
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Vds
Vgs
Ids=f(Vgs,Vds)
DS
VDS
GS
VGS
GSDSGSDSDS
DSDSDSDSDSDS
vv
fv
v
fVVfvvfi
iIivVv
GSDS
),(),(
,
Transconductance: gm gd :Output conductance
Small signal analysis:
High speed design: Common-source amplifier
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Vds
RL
vi
vo
+-
gdeqLmgsg
eqLm
i
ov
CRgCRjRg
v
vfA
,
,11
1
106
107
108
109
1010
1011
-5
0
5
10
15
Frequency (Hz)
Voltage G
ain
(dB
)
3dB point
Voltage gain:
DC-gain
High gain, large 3dB roll off point: Large gm, small gd, small C’s!
Meyer, Gray: Chapter 7
