scholarly journals High Threshold Voltage Normally off Ultra-Thin-Barrier GaN MISHEMT with MOCVD-Regrown Ohmics and Si-Rich LPCVD-SiNx Gate Insulator

Energies ◽  
2020 ◽  
Vol 13 (10) ◽  
pp. 2479
Author(s):  
Hsiang-Chun Wang ◽  
Hsien-Chin Chiu ◽  
Chong-Rong Huang ◽  
Hsuan-Ling Kao ◽  
Feng-Tso Chien
Keyword(s):  
Threshold Voltage ◽  
Gate Insulator ◽  
High Threshold ◽  
Potential Candidate ◽  
Channel Mobility ◽  
Switching Power ◽  
Selective Area ◽  
Inversion Channel ◽  
Threshold Voltage Distribution ◽  
Dimensional Electron Gas

A high threshold voltage (VTH) normally off GaN MISHEMTs with a uniform threshold voltage distribution (VTH = 4.25 ± 0.1 V at IDS = 1 μA/mm) were demonstrated by the selective area ohmic regrowth technique together with an Si-rich LPCVD-SiNx gate insulator. In the conventional GaN MOSFET structure, the carriers were induced by the inversion channel at a high positive gate voltage. However, this design sacrifices the channel mobility and reliability because a huge number of carriers are beneath the gate insulator directly during operation. In this study, a 3-nm ultra-thin Al0.25Ga0.75N barrier was adopted to provide a two-dimensional electron gas (2DEG) channel underneath the gate terminal and selective area MOCVD-regrowth layer to improve the ohmic contact resistivity. An Si-rich LPCVD-SiNx gate insulator was employed to absorb trace oxygen contamination on the GaN surface and to improve the insulator/GaN interface quality. Based on the breakdown voltage, current density, and dynamic RON measured results, the proposed LPCVD-MISHEMT provides a potential candidate solution for switching power electronics.

Effect of Graphite Cap for Implant Activation on Inversion Channel Mobility in 4H-SiC MOSFETs

2009 ◽  
Vol 615-617 ◽  
pp. 773-776 ◽  
Author(s):  
Harsh Naik ◽  
K. Tang ◽  
T. Paul Chow
Keyword(s):  
Low Temperature ◽  
Carrier Concentration ◽  
Threshold Voltage ◽  
Hall Mobility ◽  
Field Effect ◽  
Gate Oxide ◽  
Subthreshold Slope ◽  
Field Effect Mobility ◽  
Channel Mobility ◽  
Inversion Channel

The effects of using a graphite capping layer during implant activation anneal on the performance of 4H-SiC MOSFETs has been evaluated. Two sets of samples, one with the graphite cap and another without, with a gate oxide process consisting of a low-temperature deposited oxide followed by NO anneal at 1175°C for 2hrs were used for characterization. Various device parameters, particularly threshold voltage, subthreshold slope, field-effect mobility, inversion sheet carrier concentration and Hall mobility have been extracted for the two processes.

Reliable 4H-SiC MOSFET with High Threshold Voltage by Al2O3-Inserted Gate Insulator

2015 ◽  
Vol 821-823 ◽  
pp. 725-728
Author(s):  
Akio Shima ◽  
Kikuo Watanabe ◽  
Toshiyuki Mine ◽  
Naoki Tega ◽  
Hirotaka Hamamura ◽  
...  
Keyword(s):  
Threshold Voltage ◽  
Gate Voltage ◽  
Gate Insulator ◽  
High Threshold ◽  
Term Operation ◽  
Device Reliability

We investigated the effect of an Al2O3 insertion layer in the gate insulator to make Vth higher and to improve the transconductance Gm in a SiC-MOSFET. Insertion of the Al2O3 layer successfully enlarged Vth by about 4 V. The Vth difference sub-threshold Id-Vg characteristics measured by sweeping the gate voltage bi-directionally indicates that insertion of the Al2O3 layer decreased the number of traps of electrons in the gate insulator. Due to this decrease, device reliability in long-term operation was improveed by smaller Vth shift in PBTI. It was also found that the insertion of the Al2O3 layer improved Gm by two times. Using this gate insulator, we succeeded in fabricating 600 V 20 A-class vertical SiC DMOSFETs with a high Vth (>5 V) and low Ron of 3 mΩcm2.

High Threshold Voltage Uniformity and Low Hysteresis Recessed-Gate Al2O3/AlN/GaN MISFET by Selective Area Growth

2017 ◽  
Vol 64 (4) ◽  
pp. 1554-1560 ◽  
Author(s):  
Liang He ◽  
Fan Yang ◽  
Liuan Li ◽  
Zijun Chen ◽  
Zhen Shen ◽  
...  
Keyword(s):  
Threshold Voltage ◽  
High Threshold ◽  
Selective Area Growth ◽  
Selective Area ◽  
Area Growth ◽  
Recessed Gate

Novel Gate Oxide Process for Realization of High Threshold Voltage in 4H-SiC MOSFET

2014 ◽  
Vol 778-780 ◽  
pp. 985-988 ◽  
Author(s):  
Masayuki Furuhashi ◽  
Toshikazu Tanioka ◽  
Masayuki Imaizumi ◽  
Naruhisa Miura ◽  
Satoshi Yamakawa
Keyword(s):  
Threshold Voltage ◽  
Carrier Mobility ◽  
Positive Charge ◽  
Deep Level ◽  
Gate Oxide ◽  
High Threshold ◽  
Interface Trap Density ◽  
Wet Oxidation ◽  
Channel Mobility ◽  
Effective Carrier

We found that threshold voltage (Vth) of a 4H-SiC MOSFET increases drastically by performing low temperature wet oxidation after nitridation in a gate oxide process. The increment of Vth depends on the wet oxidation conditions. Wet oxidation increases the interface trap density (Dit) at deep level of SiC bandgap and decreases positive charge density inside the gate oxide layer. The amount change of the interface traps and the positive charges in the gate oxide makes Vth higher without a decrease in the channel mobility. We improved the trade-off between Vth and effective carrier mobility (μeff) in the MOSFET channel, and realized a low specific on-resistance (Ron,sp) SiC-MOSFET with Vth over 5 V by using the newly developed process.

Realization of Low On-Resistance 4H-SiC Power MOSFETs by Using Retrograde Profile in P-Body

2007 ◽  
Vol 556-557 ◽  
pp. 827-830 ◽  
Author(s):  
Keiko Fujihira ◽  
Naruhisa Miura ◽  
Tomokatsu Watanabe ◽  
Yukiyasu Nakao ◽  
Naoki Yutani ◽  
...  
Keyword(s):  
Body Surface ◽  
Threshold Voltage ◽  
Structural Parameter ◽  
Channel Mobility ◽  
Power Mosfets ◽  
Inversion Channel ◽  
Blocking Voltage

Inversion-type 4H-SiC power MOSFETs using p-body implanted with retrograde profiles have been fabricated. The Al concentration at the p-body surface (Nas) is varied in the range from 5×1015 to 2×1018 cm-3. The MOSFETs show normally-off characteristics. While the Ron is 3 cm2 at Eox = (Vg-Vth)/dox ≅ 3 MV/cm for the MOSFET with the Nas of 2×1018 cm-3, the Ron is reduced by a decrease in the Nas and 26 mcm2 is attained for the device with the Nas of 5×1015 cm-3. The inversion channel mobility and threshold voltage are improved with a decrease in the Nas. By modifying the structural parameter of the MOSFET, a still smaller Ron of 7 mcm2 is achieved with a blocking voltage of 1.3 kV.

Multiscale Modeling and Analysis of the Nitridation Effect of SiC/SiO2 Interface

2010 ◽  
Vol 645-648 ◽  
pp. 479-482
Author(s):  
Aveek Chatterjee ◽  
Kevin Matocha ◽  
Vinayak Tilak ◽  
Jody Fronheiser ◽  
Hong Piao
Keyword(s):  
Threshold Voltage ◽  
Photoelectron Spectroscopy ◽  
Atomic Scale ◽  
Computational Techniques ◽  
Modeling And Analysis ◽  
Channel Mobility ◽  
Inversion Channel ◽  
Nitrogen Concentrations ◽  
And Inversion

We explain the role of nitrogen in simultaneously increasing the inversion channel mobility and reducing the threshold voltage of SiC MOSFET. A variety of computational techniques have been used to compute the atomic scale configuration of a nitridated SiC/SiO2 interface, and the corresponding change in Fermi level, inversion channel mobility, and threshold voltage. X-ray photoelectron spectroscopy (XPS) has been used to investigate the SiC/SiO2 interface to determine the nitrogen concentrations and chemical bonding. We elucidate the physics behind improved channel mobility due to NO anneal and demonstrate that the trade-off between threshold voltage and inversion channel mobility can be correlated to the extent of nitridation.

1200 V SiC IE-UMOSFET with Low On-Resistance and High Threshold Voltage

2017 ◽  
Vol 897 ◽  
pp. 497-500 ◽  
Author(s):  
Shinsuke Harada ◽  
Yusuke Kobayashi ◽  
A. Kinoshita ◽  
N. Ohse ◽  
Takahito Kojima ◽  
...  
Keyword(s):  
Threshold Voltage ◽  
Gate Voltage ◽  
Gate Oxide ◽  
Critical Issue ◽  
High Threshold ◽  
Trade Off ◽  
Negative Gate Voltage

A critical issue with the SiC UMOSFET is the need to develop a shielding structure for the gate oxide at the trench bottom without any increase in the JFET resistance. This study describes our new UMOSFET named IE-UMOSFET, which we developed to cope with this trade-off. A simulation showed that a low on-resistance is accompanied by an extremely low gate oxide field even with a negative gate voltage. The low RonA was sustained as Vth increases. The RonA values at VG=25 V (Eox=3.2 MV/cm) and VG=20V (Eox=2.5 MV/cm), respectively, for the 3mm x 3mm device were 2.4 and 2.8 mWcm2 with a lowest Vth of 2.4 V, and 3.1 and 4.4 mWcm2 with a high Vth of 5.9 V.

SiC MOSFET Channel Mobility Dependence on Substrate Doping and Temperature Considering High Density of Interface Traps

2007 ◽  
Vol 556-557 ◽  
pp. 835-838 ◽  
Author(s):  
Amador Pérez-Tomás ◽  
Michael R. Jennings ◽  
Philip A. Mawby ◽  
James A. Covington ◽  
Phillippe Godignon ◽  
...  
Keyword(s):  
Degradation Mechanism ◽  
Mobility Model ◽  
Effect Of Temperature ◽  
Coulomb Scattering ◽  
Interface Traps ◽  
Channel Mobility ◽  
Inversion Channel ◽  
Scattering Effects ◽  
Charge Concentration ◽  
Substrate Doping

In prior work we have proposed a mobility model for describing the mobility degradation observed in SiC MOSFET devices, suitable for being implemented into a commercial simulator, including Coulomb scattering effects at interface traps. In this paper, the effect of temperature and doping on the channel mobility has been modelled. The computation results suggest that the Coulomb scattering at charged interface traps is the dominant degradation mechanism. Simulations also show that a temperature increase implies an improvement in field-effect mobility since the inversion channel concentration increases and the trapped charge is reduced due to bandgap narrowing. In contrast, increasing the substrate impurity concentration further degrades the fieldeffect mobility since the inversion charge concentration decreases for a given gate bias. We have good agreement between the computational results and experimental mobility measurements.

Normally-off operation AlGaN/GaN MOS-HEMT with high threshold voltage

2010 ◽  
Vol 46 (18) ◽  
pp. 1280 ◽  
Author(s):  
C.-T. Chang ◽  
T.-H. Hsu ◽  
E.Y. Chang ◽  
Y.-C. Chen ◽  
H.-D. Trinh ◽  
...  
Keyword(s):  
Threshold Voltage ◽  
High Threshold
Sign in / Sign up

Export Citation Format

Share Document