Combined N2O and Phosphorus Passivations for the 4H-SiC/SiO2 Interface with Oxide Grown at 1400°C

2017 ◽  
Vol 897 ◽  
pp. 344-347
Author(s):  
Hua Rong ◽  
Yogesh K. Sharma ◽  
Philip A. Mawby
Keyword(s):  
Field Effect ◽  
Field Effect Mobility ◽  
Mos Capacitors ◽  
Peak Field

Phosphorus (P) passivation is more effective than N2O passivation in improving the 4H-SiC/ SiO2 interface by reducing the number of traps at the 4H-SiC/SiO2 interface. This paper investigated the effect of combined N2O and phosphorus POA on the 4H-SiC/SiO2 interface with oxides grown at 1400°C and used in the fabrication of MOS capacitors and FETs. These fabricated devices are also compared with the ones which have been N2O and P passivations only. Results demonstrated that the phosphorus passivation technique provides the highest peak field-effect mobility for 4H-SiC MOSFETs (60 cm2/V.s), which is about 5 times higher than the value obtained for devices with N2O annealing. The combined N2O and phosphorus passivation technique, however, has shown a slight decrease in the peak field effect mobility value compared to the phosphorus passivation technique, but it is still much higher than the N2O passivation technique (12 cm2/V.s).

Gamma Irradiation Effects on 4H-SiC MOS Capacitors and MOSFETs

2006 ◽  
Vol 527-529 ◽  
pp. 1063-1066 ◽  
Author(s):  
Ayayi Claude Ahyi ◽  
S.R. Wang ◽  
John R. Williams
Keyword(s):  
Field Effect ◽  
Gamma Dose ◽  
Interface Traps ◽  
Valence Band Edge ◽  
Field Effect Mobility ◽  
Irradiation Effects ◽  
Mos Capacitors ◽  
Channel Mobility ◽  
Radiation Induced ◽  
Radiation Tolerant

The effects of gamma radiation on field effect mobility and threshold voltage have been studied for lateral n-channel 4H-SiC MOSFETs passivated with nitric oxide. MOS capacitors (n and p) and n-channel lateral MOSFETs were irradiated unbiased (floating contacts) for a total gamma dose of 6.8Mrad (Si). The MOS capacitors were used to study the radiation-induced interface traps and fixed oxide charge that affect the performance of the MOSFETs. Radiationinduced interface traps were observed near the SiC valence band edge and just above mid-gap, and field effect channel mobility was reduced by 18-20% following irradiation. Even so, 4HMOSFETs appear to be more radiation tolerant than Si devices.

High Field Effect Mobility in Si Face 4H-SiC MOSFET Made on Sublimation Grown Epitaxial Material

2005 ◽  
Vol 483-485 ◽  
pp. 841-844 ◽  
Author(s):  
Einar Ö. Sveinbjörnsson ◽  
H.Ö. Ólafsson ◽  
G. Gudjónsson ◽  
Fredrik Allerstam ◽  
Per Åke Nilsson ◽  
...  
Keyword(s):  
Chemical Vapor Deposition ◽  
Surface Morphology ◽  
Vapor Deposition ◽  
Field Effect ◽  
High Field ◽  
Chemical Vapor ◽  
Field Effect Mobility ◽  
Fabrication And Characterization ◽  
Peak Field

We report on fabrication and characterization of n-channel Si face 4H-SiC MOSFETs made using sublimation grown epitaxial material. Transistors made on this material exhibit record-high peak field effect mobility of 208 cm2/Vs while reference transistors made on a commercial epitaxial material grown by chemical vapor deposition (CVD) show field effect mobility of 125 cm2/Vs. The mobility enhancement is attributed to better surface morphology of the sublimation grown epitaxial layer.

Field Effect Mobility in n-Channel Si Face 4H-SiC MOSFET with Gate Oxide Grown on Aluminium Ion-Implanted Material

2005 ◽  
Vol 483-485 ◽  
pp. 833-836 ◽  
Author(s):  
G. Gudjónsson ◽  
H.Ö. Ólafsson ◽  
Fredrik Allerstam ◽  
Per Åke Nilsson ◽  
Einar Ö. Sveinbjörnsson ◽  
...  
Keyword(s):  
Field Effect ◽  
Functional Relationship ◽  
Gate Oxide ◽  
Aluminum Concentration ◽  
Field Effect Mobility ◽  
P Type ◽  
Channel Region ◽  
Mobility Reduction ◽  
Peak Field ◽  
Ion Implanted

We report investigations of Si face 4H-SiC MOSFETs with aluminum ion implanted gate channels. High quality SiO2/SiC interface is obtained both when the gate oxide is grown on p-type epitaxial material and when grown on ion implanted regions. A peak field effect mobility of 170 cm2/Vs is extracted from transistors with epitaxially grown channel region of doping 5x1015 cm-3. Transistors with implanted gate channels with aluminum concentration of 1x1017 cm-3 exhibit peak field effect mobility of 108 cm2/Vs, while the mobility is 62 cm2/Vs for aluminum concentration of 5x1017 cm-3. The mobility reduction with increasing acceptor density follows the same functional relationship as in n-channel Si MOSFETs.

Effect of NH3 Post-Oxidation Annealing on Flatness of SiO2/SiC Interface

2013 ◽  
Vol 740-742 ◽  
pp. 723-726 ◽  
Author(s):  
Narumasa Soejima ◽  
Taishi Kimura ◽  
Tsuyoshi Ishikawa ◽  
Takahide Sugiyama
Keyword(s):  
Nitrous Oxide ◽  
Field Effect ◽  
Inversion Layer ◽  
Trap Density ◽  
Interface Trap Density ◽  
Interface Trap ◽  
Field Effect Mobility ◽  
Interfacial Roughness ◽  
Cross Sectional ◽  
Mos Capacitors

We investigated the effects of the post-oxidation annealing (POA) atmosphere on the electrical properties and interfacial roughness of SiO2 deposited on a 4H-SiC (0001) face and SiC. POA in ammonia (NH3) gave MOS capacitors with a lower interface trap density and n-channel MOSFETs with higher field-effect mobility than POA in nitrous oxide (N2O) or nitrogen (N2). In contrast, POA in N2O gave a lower interface trap density than POA in N2, but it gave the lowest field-effect mobility of all the samples. Cross-sectional TEM observations revealed that N2O POA gave a higher interfacial roughness than NH3 POA. We thus considered that N2O POA degraded the inversion-layer mobility due to increased roughness scattering.

Correlation between Field Effect Mobility and Accumulation Conductance at 4H-SiC MOS Interface with Barium

2018 ◽  
Vol 924 ◽  
pp. 477-481
Author(s):  
Kosuke Muraoka ◽  
Seiji Ishikawa ◽  
Hiroshi Sezaki ◽  
Tomonori Maeda ◽  
Shinichiro Kuroki
Keyword(s):  
Linear Correlation ◽  
Field Effect ◽  
Interface State ◽  
State Density ◽  
Interface State Density ◽  
Field Effect Mobility ◽  
Mos Capacitors

A correlation between field effect mobility and an accumulation conductance has been investigated at 4H-SiC MOS interface with barium. 4H-SiC n-channel MOSFETs and n-type MOS capacitors were fabricated with a barium-introduced SiO2and a conventional dry SiO2. The field effect mobility was enhanced by introducing the barium-introduced SiO2. It is found that there is a linear correlation between the mobility and the accumulation conductance. The MOS interface of the barium-introduced SiO2had a lower interface state density of 2×1011cm-2eV-1than that of the conventional dry SiO2.

High Channel Mobility 4H-SiC MOSFETs

2006 ◽  
Vol 527-529 ◽  
pp. 961-966 ◽  
Author(s):  
Einar Ö. Sveinbjörnsson ◽  
G. Gudjónsson ◽  
Fredrik Allerstam ◽  
H.Ö. Ólafsson ◽  
Per Åke Nilsson ◽  
...  
Keyword(s):  
Field Effect ◽  
Phonon Scattering ◽  
Conduction Band Edge ◽  
Clear Correlation ◽  
Stable Operation ◽  
Interface Traps ◽  
Field Effect Mobility ◽  
Threshold Voltage Shift ◽  
Mos Capacitors ◽  
Positive Threshold

We report investigations of MOS and MOSFET devices using a gate oxide grown in the presence of sintered alumina. In contrast to conventionally grown dry or wet oxides these oxides contain orders of magnitude lower density of near-interface traps at the SiO2/SiC interface. The reduction of interface traps is correlated with enhanced oxidation rate. The absence of near-interface traps makes possible fabrication of Si face 4H-SiC MOSFETs with peak field effect mobility of about 150 cm2/Vs. A clear correlation is observed between the field effect mobility in n-channel MOSFETs and the density of interface states near the SiC conduction band edge in n-type MOS capacitors. Stable operation of such normally-off 4H-SiC MOSFET transistors is observed from room temperature up to 150°C with positive threshold voltage shift less than 1 V. A small decrease in current with temperature up to 150°C is related to a decrease in the field effect mobility due to phonon scattering. However, the gate oxides contain sodium, which originates from the sintered alumina, resulting in severe device instabilities during negative gate bias stressing.

SiC and GaN MOS Interfaces – Similarities and Differences

2010 ◽  
Vol 645-648 ◽  
pp. 473-478 ◽  
Author(s):  
T. Paul Chow
Keyword(s):  
Carrier Concentration ◽  
Threshold Voltage ◽  
Field Effect ◽  
Gate Oxide ◽  
Electron Trapping ◽  
Electrical Characteristics ◽  
Subthreshold Slope ◽  
Field Effect Mobility ◽  
Mos Capacitors ◽  
Similarities And Differences

We have comparatively characterized the electrical characteristics of 4H-SiC and 2H-GaN MOS capacitors and FETs. While progressive refinement of gate oxide processes, notably with NO anneal, has resulted in better threshold voltage control, reduced subthreshold slope and higher field-effect mobility for 4H-SiC MOSFETs, we have recently reported more superior MOS parameters for 2H-GaN MOSFETs. In addition, we have performed MOS-gated Hall measurements to extract the intrinsic carrier concentration and MOS mobility, indicating that both less channel electron trapping and scattering take place in 2H-GaN MOSFETs.

Progress in GaN MOSFET Technology

2008 ◽  
Vol 600-603 ◽  
pp. 1263-1268 ◽  
Author(s):  
T. Paul Chow ◽  
W. Huang ◽  
T. Khan ◽  
K. Matocha ◽  
Y. Wang
Keyword(s):  
Field Effect ◽  
Interface State ◽  
Orientation Dependence ◽  
State Density ◽  
Interface State Density ◽  
Field Effect Mobility ◽  
Mos Capacitors ◽  
Enhancement Mode ◽  
Current Collapse ◽  
Non Destructive

GaN MOS capacitors were characterized to optimize the electric properties of SiO2/GaN interface. With optimized anneal conditions, an interface state density of 3.8×1010/cm2-eV was estimated at 0.19 eV near the conduction band and decreases deeper into the band gap. Enhancement-mode GaN MOSFETs were experimentally demonstrated on both p and n GaN epilayer with record high field-effect mobility of 167 cm2/V-s. Lateral RESURF-type GaN MOSFETs exhibit non-destructive high voltage (up to 940V) blocking capabilities. Other characterization including mobility orientation dependence, MOS-gated Hall mobility, current collapse and an NMOS inverter utilizing E/D mode GaN MOSFETs have also been experimentally demonstrated.

Surface Treatment of 4H-SiC MOSFETs Prior to Al2O3 Deposition

2020 ◽  
Vol 1004 ◽  
pp. 541-546
Author(s):  
Muhammad Idzdihar Idris ◽  
Alton B. Horsfall
Keyword(s):  
Surface Treatment ◽  
Field Effect ◽  
High Performance ◽  
Interface State ◽  
State Density ◽  
Interface State Density ◽  
Surface Treatments ◽  
Flat Band ◽  
Field Effect Mobility ◽  
Mos Capacitors

The effect of surface treatments prior to the deposition of Al2O3 is performed on 4H-SiC MOS capacitors and MOSFETs. 40 nm of Al2O3 were deposited on 4H-SiC using atomic layer deposition (ALD) as a gate dielectric. Different surface treatments were used to investigate the capacitance-voltage and current-voltage characteristics on MOS capacitors and MOSFETs respectively, including the important parameters such as interface state density, flat band voltage, threshold voltage and field-effect mobility. Forming gas annealing and rapid oxidation processes were found to be effective in reducing the interface state density and results in high field-effect mobility with peak field-effect mobility of 130 cm2Vs-1. The experimental results obtained manifest that the surface treatment prior to Al2O3 deposition is critical to producing high performance of 4H-SiC MOSFETs.

Characterization of Interface State Density from Subthreshold Slope of MOSFETs at Low Temperatures (≥ 10 K)

2015 ◽  
Vol 821-823 ◽  
pp. 745-748
Author(s):  
Hironori Yoshioka ◽  
Junji Senzaki ◽  
Atsushi Shimozato ◽  
Yasunori Tanaka ◽  
Hajime Okumura
Keyword(s):  
Low Temperatures ◽  
Field Effect ◽  
Gate Oxide ◽  
Interface State ◽  
State Density ◽  
Interface State Density ◽  
Subthreshold Slope ◽  
Field Effect Mobility ◽  
Peak Field

We have evaluated interface state density (DIT) for EC−ET > 0.00 eV from the subthreshold slope deterioration of MOSFETs at low temperatures. We have compared two n-channel MOSFETs on the C- and a-faces with the gate oxide formed by pyrogenic oxidation followed by annealing in H2. The peak field-effect mobility (µFE,peak) for the C-face MOSFET was 57 cm2V-1s-1 at 300 K, which is lower than the half of 135 cm2V-1s-1 for the a-face MOSFET. We have shown that DIT very close to EC can well explain why µFE for C-face MOSFETs is lower than that for a-face MOSFETs. The value of DIT at 0.00 eV corresponding to the subthreshold slope at 11 K was 1.6×1014 cm-2eV-1 for the C-face MOSFET, which is more than the double of 6.4×1013 cm-2eV-1 for the a-face MOSFET.

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