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Analysis and Characterization of GaN-HEMT Devices for Switching Converter Applications

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Giovanni Parrino

on 6 March 2013

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Transcript of Analysis and Characterization of GaN-HEMT Devices for Switching Converter Applications

Analysis and Characterization
of GaN-HEMT Devices for
Switching Converter Applications Relatore: Prof. A. Raciti
Correlatore: Dott. A. Patti
Ing. G. Sorrentino State-of-the-art and Application Giovanni Parrino Analysis and Characterization
of GaN-HEMT Devices for
Switching Converter Applications Giovanni Parrino UNIVERSITÀ DEGLI STUDI DI CATANIA
FACOLTÀ DI INGEGNERIA

Corso di Laurea Magistrale in Ingegneria Elettronica
Dipartimento di Ingegneria Elettrica, Elettronica e Informatica Experimental Results Thesis Workplace: HEMTs – High Electron Mobility Transistors …on Si substrates GaN… High yield,
High throughput
Large wafer size
Low cost devices High bandgap energy
High saturation velocity
High electrical strength Low on - resistance
Low parasitic capacitances
Fast switching times
High efficiency Why GaN-on-Si HEMTs? Like any other HFET, GaN-on-Si HEMT is gate-voltage controlled Challenges to overcome Reproducibility
Trapping Effects
Reliability
Heat Dissipation GaN HEMTs: an overview VGS = 0 V Furthermore, GaN HEMTs are normally-on (depletion-mode) devices… Nucleation Layer
Buffer thickness / doping
Al Concentration
Field Plate (FP)
Passivation Layer
MIS- or MOS-HEMTs
DHFETs… VGS < 0 V Some designers' choices... Device Fabrication A normally-off (VTH > 0 V) device
is preferred because:

Fail-safe nature
Less drive circuit complexity
System cost reduction Several approaches exist to realize
an e-mode GaN-on-Si HEMT:

Thin AlGaN barrier layer
Gate recession
Fluorine Plasma Bombardment…
Cascode Connection E-mode vs. D-mode HEMTs IMS R&D STMicroelectronics Catania 600-V class characterized devices: 8mm, 25mm
20mm, 40mm, 80mm
25mm Normally-On HEMTs
Normally-Off HEMTs
Cascode-Connected HEMTs Static Measurements Some important charts: ID vs. VDS, ID vs. VGS, TLM, C - V... Changing the quiescent points (gate and drain lag),
static parameters may vary because of trapping effects:
Current Collapse - Ron increase - Vth shift… Pulsed I – V Measurements Resistive and Clamped Inductive Load measurements have been performed
for all characterized devices in order to evaluate rise- and fall- times, and energy switching losses Dynamic Measurements
Ron · Qg, Ron · Qgd
Ron · Ciss, Ron · Coss
BV^2 / RonA
RDS (on) A vs. BV Static & Dynamic FOMs Dynamic FOMs Static FOMs To evaluate characterized 40mm normally-off GaN-on-Si HEMT switching performances in a real application, a 300-V DC-DC boost converter circuit has been designed and realized with discrete components. Moreover, an efficiency comparison with a commercial Si MOSFET on same board has been performed Boost Converter Experimental Waveforms
Gate voltage oscillations
Device overheating
Voltage and current spikes
Poor reliability
Decreased efficiency
Dedicated gate drive on PCB
Better boost converter design
Better thermal management Issues and Challenges Problems Solutions High-temperature
characterization Optimized gate drive
on PCB Higher reliability Higher threshold Voltage
in normally - off devices Detailed traps characterization Larger wafer size Better device design There is much work to do, but we are on the right way! Improved material growth Conclusions and Future Works
Full transcript