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Figures
(a)
(b)
Figure 2-1 (a) The polarizations in GaN HEMT structure. (b) How these polarizations affect the concentration of 2DEG in AlGaN/GaN HEMT.
Figure 2-2 The comparisons of bandgaps energy and lattice constant of various binary semiconductors.
Gate Dimension: 1 × 100 µm2
Figure 3-1 The cross-sectional GaN/ AlGaN/GaN structure of conventional HEMT.
Gate Dimension: 1 × 100 µm2
Figure 3-2 The cross-sectional GaN/ AlGaN/GaN structure of MgO MOS-HEMT.
Step 2
Mesa Isolation
Mesa Photolithography
Evaporate Ni and Lift-off
Dry Etching by ICP/RIE
Ni Remove by HNO3
Evaporate Ti/Al/Au and Lift-off
Annealing by RTA
S/D Ohmic contact
Step 4
Gate Photolithography
Evaporate Ni/Au and Lift-off
Gate Schottky Contact
Si substrate
Step 1-3 Step 6
Gate Oxide Deposition by USPD
S/D Photolithography
MgO Remove by H3PO4
Step 7
Gate Photolithography
Evaporate Ni/Au and Lift-off
Gate Schottky Contact Figure 3-3 A Conventional HEMT device of fabrication process.
Figure 3-4 A MOS-HEMT device of fabrication process.
Figure 3-5 Schematic diagram of the ultrasonic spray pyrolysis technology.
HEAT
350C
Reactive gas
Ultrasonic Atomizer Exhaust
Sample
Hot plate heater
Chamber
H2O
H2O
Precursor solution
Gas flux controller
Figure 4-1 Structure of XPS measurement system.
46 48 50 52 54
Intensity (arb. unit)
Binding Energy (eV) Mg 2p
Figure 4-2 X-ray Photoelectron Spectrometer spectra of Mg.
526 528 530 532 534
Intensity (arb. unit)
Binding Energy (eV) O 1s
Figure 4-3 X-ray Photoelectron Spectrometer spectra of O.
Figure 4-4 he depth profile of devices.
Figure 4-5 TEM analysis of MgO film.
Figure 4-6 Structure of atomic force microscopy measurement system.
Figure 4-7 AFM analysis of two dimension MgO film.
Figure 4-8 AFM analysis of three dimension MgO film.
Figure 4-9 Summary of USPD treatment thickness optimization transfer characteristics for MOS-HEMT.
Figure 4-10 Current-Voltage characteristics of the conventional HEMT at room temperature
Figure 4-11 Current-Voltage characteristics of the MgO MOS-HEMT at room temperature.
Figure 4-12 Extrinsic transconductance (gm) and the drain leakage current (IDS) of the conventional HEMT at room temperature.
Figure 4-13 Extrinsic transconductance (gm) and the drain leakage current (IDS) of the MOS-HEMT at room temperature.
-6 -5 -4 -3 -2 -1 0 1 2
0 5 10 15 20
Conventional HEMT MOS-HEMT
@VDS = 7 V
Gate-Source Voltage (V) Squrt I D
Figure 4-14 The threshold voltage (Vth) characteristics of all devices.
Figure 4-15 Two-terminal off state gate-drain breakdown voltage (BVGD) characteristics of all devices.
Figure 4-16 Two-terminal off state gate-drain turn-on voltage (Von) characteristics of all devices.
Figure 4-17 Three-terminal off-state breakdown voltage (BVoff) characteristics of all devices.
Figure 4-18 Temperature-dependent DC characteristics of the conventional HEMT from 300 K to 450 K.
Figure 4-19 Temperature-dependent DC characteristics of the MOS-HEMT from 300 K to 450 K.
Figure 4-20 Extrinsic transconductance and saturation drain current density of the conventional HEMT from 300 K to 450 K.
Figure 4-21Extrinsic transconductance and saturation drain current density of the MOS-HEMT from 300 K to 450 K.
Figure 4-22 Temperature-dependent two-terminal breakdown characteristics of the conventional HEMT from 300 K to 450 K.
Figure 4-23 Temperature-dependent two-terminal breakdown characteristics of the MOS-HEMT from 300 K to 450 K.
Figure 4-24 Capacitance voltage characteristics of all devices.
Figure 4-25 Hysteresis of metal-semiconductor (M-S) Schottky diode.
-6 -5 -4 -3 -2 -1 0
0 4 8 12 16
MOS Diode @ 1M Hz
Voltage (V)
Capaticance (pF)
Figure 4-26 Hysteresis of metal-oxide-semiconductor (M-O-S) diode.
Figure 4-27 Capacitance-voltage characteristics of MOS diode, the inset shows the calculated Dit-V characteristics.
Figure 4-28 fT and fmax characteristics of all devices.
-20 -15 -10 -5 0 5 10
Figure 4-29 The power-added-efficiency (P. A. E.), output power (Pout), associated gain (Ga) characteristics at 2.4 GHz for conventional
Figure 4-30 The power-added-efficiency (P. A. E.), output power (Pout), associated gain (Ga) characteristics at 2.4 GHz for MOS-HEMT.
-20 -15 -10 -5 0 5 10
Figure 4-31 The power-added-efficiency (P. A. E.), output power (Pout), associated gain (Ga) characteristics at 5.8 GHz for conventional
Figure 4-32 The power-added-efficiency (P. A. E.), output power (Pout), associated gain (Ga) characteristics at 5.8 GHz for MOS-HEMT.
Figuer 4-33 The minimum noise figure (NFmin) and associated gain (Ga) characteristics versus frequencies of all devices.
Figure 4-34 Low frequency noise characteristics versus frequency of all devices.
Figure 4-35 The CW and pulse characteristics of conventional HEMT.
Figure 4-36 The CW and pulse characteristics of MOS-HEMT.