introduction on my current research...
TRANSCRIPT
Introduction on My Current Research Interest
Albert Shihchun Lin, National Chiao‐Tung University, Hsinchu, Taiwan
8/18/2016NCTUEE 1
Biography
8/18/2016NCTUEE 2
http://albertlin.weebly.com/
Nano‐photonics
Device Simulation
8/18/2016NCTUEE 3
Current Research Interest
Optoelectronics Devices
Device Process
Power devices are fundamental components (switch, rectifier) for power converters which have wide applications and are indispensable in electrical products.
Power Devices, Circuits and Applications
Sensor
Actuator • The PicoCube is a 1 cm3 sensor node using harvested energy as its source of power.
• Combines advanced ultra‐low power circuit techniques with system‐level power management.
• Represents an integrated approach to the design of nodes for wireless sensor networks.
sensors
Powering & Power management
Power source
Power devices in “Internet of things (IoT)” technology‐Enabling operation of CMOS low voltage processor, embedded memory and sensor/actuator
system in IoT devices from micro‐battery, energy‐harvesting source, or AC power line via enhancing power conversion efficiency and power management capabilities.
*IoT device *Example: PicoCube sensor
Visions & Driving Forces for Power Devices
*More than Moore White Paper, ITRS
Visions & Driving Forces for Power Devices Power devices in Green technology‐Entire electrical energy “ food chain” from generation via distribution to consumption, in all
segments power device are required and as keys to against pollution and fuel consumption by enabling more renewable energy source and saving more energy loss.
*Example: Smart City Applications (smart grid, solar/wind turbine inverter, E‐car powering, smart lighting..)
*Source: Infineon
Conversion Efficiency and Operating Area Improvement• Reduced losses (switching and conduction)• Higher Voltage• Higher Current• Higher Frequency
Lighter cooling systems• Higher thermal conductivity
Reduced volume and weight• Higher integration• Smaller passive components (higher frequency)
Devices Requirements & Evolutions in Power Electronics
*Structure evolution of Si devices
*Material evolution : Si SiC & GaN
FOM
GaNGaN
SiC
Si
Breakdown Voltage @different pillar length(D)Super Junction MOSFET structure breaks the trade‐off between breakdown voltage and on‐resistance(Ron). High breakdown voltage due to charge
compensation in the N‐ and P‐pillar layer. Low on‐resistance (reduced losses) due to highly
doped N‐pillar layer.
D=10um
D=30um
D=50um
Doping con. Doping con. Doping con.
Power Device‐ Super Junction DMOS
Ic‐Vc@different Vg
300K(solid)425K(dash)
Ic‐Vg
Breakdown @Vg=0V Power dissipation @switching
Power Device‐ ‐ IGBTIGBT structure has switching and conduction characteristics of a bipolar transistor but is voltage‐controlled like a MOSFET.
TA↑
CHW↑ D↑
Power Device‐ SiC IGBTSiC has wider band gap(3x) and higher critical E‐field (10x) than Si and leads to higher breakdown voltage.
Power dissipation in GaN HEMT
Circuit voltage behaviors of boost converter
Power Device‐ GaN DC Boost Converter Circuit GaN/AlGaN high‐electron mobility
transistors(HEMT) are well suited as switching elements due to high mobility and breakdown field.
Mix‐mode simulation to investigate device‐circuit interactions.
Description to Drift‐Diffusion Model for IBSC
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Illustration of the prototype intermediate band solar cell device structure and energy band diagram.
)fNpnN(Nqψεεr IDA0
nrCICVICVCn RRRGGqJ
nrIVCVVIVCp RRRGGqJ
Where is electrostatic potential, n and p are electron and hole concentration. f is the filling of the intermediate band. NI is the IB density of states.
Effect of charge in intermediate band
This cannot be simply incorporated into existing drift‐diffusion model
Lightly Doped Case
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-0.5 0 0.5 1 1.5-2
-1
0
1
2
x(m)
Ene
rgy
(eV
)
EFV
EI
EFI
EFCEC
EV
-0.5 0 0.5 1 1.5100
1010
1020
1030
x(m)
(cm
-1s-1
)
RCVRCIRIV
-0.5 0 0.5 1 1.51020
1021
1022
x(m)
(cm
-1s-1
)
GVCGICGVI
• EFI is significantly below EI , predicted high efficiency may not be achievable in practice unless Asymmetric optical absorption
cross section efficient field emission or
thermionic field emission exist between IB and CB.
• The band diagram deviate from conventional p‐i‐n (p‐‐n,n p‐ ‐n) type picture, resulting from the charge in the intermediate band
VC =IC = VI = 104 cm-1, EG = 1.95 eV, EI= 1.24 eV n = h = 100 cm2/Vs, W= 1 m, NI = 1018 cm-3 and NA (p-emitter)=ND (n-emitter)= 1018 cm-3
Periodic Grating Structure
8/18/2016NCTUEE 14Electric field profile for cells with periodic grating couplers
0)()( 22 rErE zz
• For λ = 400 nm, the incoming wave decays rapidly in device
• For λ = 1000 nm, wave bounces back and forth
Helmholtz equation is solved for E‐field
Surface Plasmon Photovoltaics
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hν hνhν
Using Surface Plasmon to increase solar cell photonic property
Waveguiding, slow light, slow Bloch mode, and energy transfer
Eigen modeField Profile
Ag
Ag AgAg
Ag
Ag
Ag
Ag Ag AgAg Ag
Ag Ag
Ag
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Device Processing
-0.1 0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9-1
0
1
2
3
4
5
6
7
8
9
AZO nanowires length= 1 m
Curr
ent d
ensi
ty (m
A/cm
2 )
Voltage (V)
AZO NW solar cell, t-Si=25nm
AZO NW solar cell, t-Si=50nm
AZO NW solar cell, t-Si=100nm
AZO NW solar cell, t-Si=150nm
AZO NW solar cell, t-Si=200nm
AZO NW solar cell, t-Si=250nm
baseline planar cell, t-Si=150nm
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Device Processing
17
Molecular Beam Epitaxy Pulsed Laser Deposition
TargetSubstrate
TargetAssy
SubstrateAssy
LaserPort
EffusionCells
(Zn, etc)
Plasma source for
oxygen Cryopanel Substrate
To BufferChamber
Shutters
Beam flux
RHEED Gun
RHEED Screen
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Theoretical and Process in parallel
Quantum Mechanics, Classical
Electrodynamics
Device Physics, Opto‐electronic
DevicesTraining on NDL
Facility
Device Process and
Characterization
Device Simulation (SentaurusDevices)
Photonics Simulation (PC Bandstructure,
etc)
Road‐Map for Incoming Master
Students
8/18/2016NCTUEE 19
Direct PhD , and my first PhD student傅思銘(Sze‐Ming Fu)
Excellent IIT exchange student
Direct PhD, great theorist
Graduate in 1 year, process integration TSMC
8/18/2016NCTUEE 20
Thank you and Welcome your visit!
Office: ED503 Phone: 0921755140Email: [email protected]: ED630