Improved Field Effect Mobility in Si-Face 4H-SiC MOSFETs with a Deposited SiNx Interface Layer

2019 ◽  
Vol 963 ◽  
pp. 469-472 ◽  
Author(s):  
Teruaki Kumazawa ◽  
Mitsuo Okamoto ◽  
Miwako Iijima ◽  
Yohei Iwahashi ◽  
Shinji Fujikake ◽  
...  
Keyword(s):  
Field Effect ◽  
Atomic Layer ◽  
Interface Layer ◽  
Interface State ◽  
State Density ◽  
Field Effect Mobility ◽  
Optimal Thickness ◽  
Interface Quality ◽  
Mos Devices ◽  
Layer Deposition

The SiO2/SiC interface quality has a significant effect on the performance of 4H-SiC MOS devices. The introduction of nitrogen to the SiO2/SiC interface is a well-known method for reducing the interface state density (Dit). In this study, we introduced nitrogen to the SiO2/SiC interface by forming SiNx films using atomic layer deposition (ALD) and thus improved the interface quality. O2 annealing with a SiNx interface layer of optimal thickness enhanced the field effect mobility.

Impact of oxide/4H-SiC interface state density on field-effect mobility of counter-doped n-channel 4H-SiC MOSFETs

2021 ◽  
Author(s):  
Takuma Doi ◽  
Shigehisa Shibayama ◽  
Mitsuo Sakashita ◽  
Noriyuki Taoka ◽  
Mitsuaki Shimizu ◽  
...  
Keyword(s):  
Field Effect ◽  
Metal Layer ◽  
Atomic Layer ◽  
Interface State ◽  
State Density ◽  
Interface State Density ◽  
Field Effect Mobility ◽  
Free Electron Density ◽  
Layer Deposition ◽  
Rate Of Increase

Abstract We investigated the effect of interface state density on the field-effect mobility (μ FE) of 4H-SiC counter-doped MOSFETs. We fabricated counter-doped MOSFETs with three types of gate oxides i.e., SiO2, Al2O3 formed via atomic layer deposition, and Al2O3 formed via metal layer oxidation (MLO). A maximum μ FE of 80 cm2/Vs was obtained for the MLO-Al2O3 FET, and this value was 60% larger than that of the SiO2 FET. In addition, we evaluated the electron mobility in the neutral channel (μ neutral) and the rate of increase in the free electron density in the neutral channel with respect to the gate voltage (dN neutral/dV G), which are factors determining μ FE. μ neutral depended only on the channel depth, independent of the type of gate oxide. In addition, dN neutral/dV G was significantly low in the SiO2 FET because of carrier trapping at the high density of interface states, whereas this effect was smaller in the Al2O3 FETs.

Investigation of Interface State Density with Varied SiO2 Thickness in La2O3/SiO2/4H-SiC MOS Capacitors

2016 ◽  
Vol 858 ◽  
pp. 689-692 ◽  
Author(s):  
Yu Cheng Wang ◽  
Yu Ming Zhang ◽  
Ren Xu Jia
Keyword(s):  
Photoelectron Spectroscopy ◽  
Lattice Mismatch ◽  
Atomic Layer ◽  
Interface State ◽  
Carbon Cluster ◽  
State Density ◽  
Oxide Semiconductor ◽  
Interface Quality ◽  
Mos Capacitors ◽  
Layer Deposition

SiO2 with varying thickness (0, 4.45, and 8.05 nm) were grown on n type 4H-SiC epilayer by thermal oxidation and La2O3 were stacked on them using atomic layer deposition (ALD). The La2O3/SiO2/4H-SiC metal-oxide-semiconductor (MOS) capacitors were analyzed by X-ray photoelectron spectroscopy (XPS) and capacitance-voltage (C-V) measurements. C-V curves show that introducing an ultrathin SiO2 can reduce the effect of lattice mismatch of La2O3/4H-SiC structure and then improve interface property. However, the interface quality is reduced as SiO2 was grown thicker. XPS data show that more carbon cluster remains at the interfacial between SiO2 and 4H-SiC as the oxidation time increases.

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.

Modelling of the Anomalous Field-Effect Mobility Peak of O-Ta2Si/4H-SiC High-k MOSFETs Measured in Strong Inversion

2006 ◽  
Vol 527-529 ◽  
pp. 1059-1062
Author(s):  
Amador Pérez-Tomás ◽  
Miquel Vellvehi ◽  
Narcis Mestres ◽  
José Millan ◽  
P. Vennegues ◽  
...  
Keyword(s):  
Field Effect ◽  
Inversion Layer ◽  
Interface State ◽  
State Density ◽  
Gate Insulator ◽  
Coulomb Scattering ◽  
Field Effect Mobility ◽  
Tunnel Current ◽  
High K ◽  
Strong Inversion

A high field-effect mobility peak (50 cm2/Vs) has been extracted in (0001) Si face 4HSiC MOSFETs with oxidized Ta2Si (O-Ta2Si) high-k dielectric (k~20) as gate insulator, with their gates in the strong inversion regime. The interface state density (Dit) has not been particularly reduced in O-Ta2Si capacitors. This anomalous mobility enhancement is explained in terms of Coulomb scattering reduction and quantified using a physical model based on the Lombardi mobility model. The anomalous mobility increase is closely related to the leakage current, and also to the gate breakdown mechanism. We propose a model for which the observed interfacial SiO2 tunnel current combined with Poole-Frenkel mechanisms at the O-Ta2Si gate generates a sufficiently low abrupt transition in gate breakdown to obtain an effective passivation of the interface traps. Under these conditions, the increase of free carriers in the inversion layer induced by the gate leakage diminishes the effect of the interface trap Coulomb scattering.

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.

Improvement of SiO2/4H-SiC Interface Quality by Post-Oxidation Annealing in N2 at High-Temperatures

2016 ◽  
Vol 858 ◽  
pp. 627-630 ◽  
Author(s):  
Atthawut Chanthaphan ◽  
Yen Hung Cheng ◽  
Takuji Hosoi ◽  
Takayoshi Shimura ◽  
Heiji Watanabe
Keyword(s):  
Photoelectron Spectroscopy ◽  
Annealing Temperature ◽  
Electrical Characterization ◽  
Practical Method ◽  
Interface State ◽  
State Density ◽  
Interface Quality ◽  
Mos Capacitors ◽  
X Ray ◽  
Mos Devices

The efficient and practical method for SiO2/4H-SiC interface improvement using post-oxidation annealing (POA) in pure N2 ambient was studied by means of x-ray photoelectron spectroscopy (XPS) analysis and electrical characterization. SiC-MOS capacitors with slope-shaped thermal oxides were used to investigate optimal conditions for interface nitridation. It was found that the amount of nitrogen atoms incorporated into the interfaces increased when raised the annealing temperature up to 1400°C, and thin oxide (< 30 nm) was used. Furthermore, N2-POA at 1400°C was proven to be very promising as equivalent to NO-POA in terms of reduced interface state density of SiC-MOS devices.

High-Mobility SiC MOSFETs with Chemically Modified Interfaces

2015 ◽  
Vol 821-823 ◽  
pp. 749-752 ◽  
Author(s):  
Daniel J. Lichtenwalner ◽  
Lin Cheng ◽  
Sarit Dhar ◽  
Anant K. Agarwal ◽  
Scott Allen ◽  
...  
Keyword(s):  
Nitric Oxide ◽  
Field Effect ◽  
Alkaline Earth ◽  
Phonon Scattering ◽  
High Mobility ◽  
Interface Layer ◽  
Interface State ◽  
State Density ◽  
Oxide Semiconductor ◽  
Alkaline Earth Elements

Alkali (Rb, Cs) and alkaline earth elements (Sr, Ba) provide SiO2/SiC interface conditions suitable for obtaining high metal-oxide-semiconductor field-effect-transistor (MOSFET) channel mobility on the 4H-SiC Si-face (0001), without the standard nitric oxide (NO) anneal. The alkali elements Rb and Cs result in field-effect mobility (μFE) values >25 cm2/V.s, and the alkaline earth elements Sr and Ba resulted in higher μFE values of 40 and 85 cm2/V.s, respectively. The Ba-modified MOSFETs show a slight decrease in mobility with heating to 150 °C, as expected when mobility is not interface-trap-limited, but phonon-scattering-limited. The interface state density is lower than that obtained with nitric oxide (NO) passivation. Devices with a Ba interface layer maintain stable mobility and threshold voltage under ±2 MV/cm gate bias stress at 175 °C, indicating no mobile ions.

Improvement of Interface State and Channel Mobility Using 4H-SiC (0-33-8) Face

2013 ◽  
Vol 740-742 ◽  
pp. 506-509 ◽  
Author(s):  
Toru Hiyoshi ◽  
Takeyoshi Masuda ◽  
Keiji Wada ◽  
Shin Harada ◽  
Yasuo Namikawa
Keyword(s):  
Field Effect ◽  
Interface State ◽  
State Density ◽  
Interface State Density ◽  
Channel Mobility ◽  
Mos Devices ◽  
Blocking Voltage

In this paper, we characterized MOS devices fabricated on 4H-SiC (0-33-8) face. The interface state density of SiO2/4H-SiC(0-33-8) was significantly low compared to that of SiO2/4H-SiC(0001). The field-effect channel mobility obtained from lateral MOSFET (LMOSFET) was 80 cm2/Vs, in spite of a high p-well concentration of 5x1017 cm-3 (implantation). The double implanted MOSFET (DMOSFET) fabricated on 4H-SiC(0-33-8) showed a specific on-resistance of 4.0 mΩcm2 with a blocking voltage of 890 V.

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