A Study on the Electronic Properties of Nitric Oxide Annealed MOS Structures Processed on 4H-SiC

2011 ◽  
Vol 1305 ◽  
Author(s):  
Kerlit Chew ◽  
Chin-Che Tin ◽  
Claude Ahyi ◽  
Kim Nie Chong ◽  
Meng Suan Liang ◽  
...  
Keyword(s):  
Nitric Oxide ◽  
Conduction Band ◽  
Drain Current ◽  
Interface State ◽  
State Density ◽  
Interface State Density ◽  
Flat Band ◽  
Mos Capacitor ◽  
Uv Illumination ◽  
Thermal Oxide

ABSTRACTInterface state density profiling of the thermal oxide / n-type 4H-SiC interface which underwent post-oxidation nitric-oxide (NO) annealing showed that an interface state density of approximately 1×1011 cm−2eV−1 could be achieved at around 0.2 eV below the conduction band. It decreased exponentially by two orders to 1×109 cm-2eV-1 at around 0.9 eV from the conduction band. The values are comparable or better than other published work. The low interface state density achieved near the conduction band is important towards improved channel carrier mobility in SiC MOSFETs. A positive flat-band voltage shift of the SiC based MOS capacitor was also observed. The shift reduced under UV illumination. It could be attributed to slow acceptor-like (negatively-charged) traps, which may have contributed to the instabilities observed in drain current and threshold voltage suffered by SiC MOSFETs.

Asymmetric Interface Densities on n and p Type GaN MOS Capacitors

2006 ◽  
Vol 527-529 ◽  
pp. 1525-1528
Author(s):  
W. Huang ◽  
T. Khan ◽  
T. Paul Chow
Keyword(s):  
Density Distribution ◽  
Valence Band ◽  
Conduction Band ◽  
Interface State ◽  
State Density ◽  
Interface State Density ◽  
Mos Capacitors ◽  
Mos Capacitor ◽  
Plasma Enhanced Cvd ◽  
P Type

Both n-type and p-type GaN MOS capacitors with plasma-enhanced CVD-SiO2 as the gate oxide were characterized using both capacitance and conductance techniques. From a n type MOS capacitor, an interface state density of 3.8×1010/cm2-eV was estimated at 0.19eV near the conduction band and decreases deeper into the bandgap while from a p type MOS capacitor, an interface state density of 1.4×1011/cm2-eV 0.61eV above the valence band was estimated and decreases deeper into the bandgap. Unlike the symmetric interface state density distribution in Si, an asymmetric interface state density distribution with lower density near the conduction band and higher density near the valence band has been determined.

The Effects of Post-Oxidation Anneal Conditions on Interface State Density Near the Conduction Band Edge and Inversion Channel Mobility for SiC MOSFETs

2000 ◽  
Vol 622 ◽  
Author(s):  
G.Y. Chung ◽  
C.C. Tin ◽  
J. R. Williams ◽  
K. McDonald ◽  
M. Di Ventra ◽  
...  
Keyword(s):  
Nitric Oxide ◽  
Conduction Band ◽  
Interface State ◽  
Interface States ◽  
State Density ◽  
Interface State Density ◽  
Band Edge ◽  
Conduction Band Edge ◽  
Channel Mobility ◽  
Inversion Channel

ABSTRACTResults are reported for the passivation of interface states near the conduction band edge in n-4H-SiC using post-oxidation anneals in nitric oxide, ammonia and forming gas (N2/5%H2). Anneals in nitric oxide and ammonia reduce the interface state density significantly, while forming gas anneals are largely ineffective. Results suggest that interface states in SiO2/SiC and SiO2/Si have different origins, and a model is described for interface state passivation by nitrogen in the SiO2/SiC system. The inversion channel mobility of 4H-SiC MOSFETs increases with the NO annealing.

scholarly journals Nitrogen Passivation of the Interface States Near the Conduction Band Edge in 4H-Silicon Carbide

2000 ◽  
Vol 640 ◽  
Author(s):  
J. R. Williams ◽  
G. Y. Chung ◽  
C. C. Tin ◽  
K. McDonald ◽  
D. Farmer ◽  
...  
Keyword(s):  
Conduction Band ◽  
Interface State ◽  
Interface States ◽  
State Density ◽  
Interface State Density ◽  
Band Edge ◽  
Conduction Band Edge ◽  
Breakdown Field ◽  
Inversion Mode ◽  
Passivation Process

ABSTRACTThis paper describes the development of a nitrogen-based passivation technique for interface states near the conduction band edge [Dit(Ec)] in 4H-SiC/SiO2. These states have been observed and characterized in several laboratories for n- and p-SiC since their existence was first proposed by Schorner, et al. [1]. The origin of these states remains a point of discussion, but there is now general agreement that these states are largely responsible for the lower channel mobilities that are reported for n-channel, inversion mode 4H-SiC MOSFETs. Over the past year, much attention has been focused on finding methods by which these states can be passivated. The nitrogen passivation process that is described herein is based on post-oxidation, high temperature anneals in nitric oxide. An NO anneal at atmospheric pressure, 1175°C and 200–400sccm for 2hr reduces the interface state density at Ec-E ≅0.1eV in n-4H-SiC by more than one order of magnitude - from > 3×1013 to approximately 2×1012cm−2eV−1. Measurements for passivated MOSFETs yield effective channel mobilities of approximately 30–35cm2/V-s and low field mobilities of around 100cm2/V-s. These mobilities are the highest yet reported for MOSFETs fabricated with thermal oxides on standard 4H-SiC and represent a significant improvement compared to the single digit mobilities commonly reported for 4H inversion mode devices. The reduction in the interface state density is associated with the passivation of carbon cluster states that have energies near the conduction band edge. However, attempts to optimize the the passivation process for both dry and wet thermal oxides do not appear to reduce Dit(Ec) below about 2×1012cm−2eV−1 (compared to approximately 1010cm−2eV−1 for passivated Si/SiO2). This may be an indication that two types of interface states exist in the upper half of the SiC band gap – one type that is amenable to passivation by nitrogen and one that is not. Following NO passivation, the average breakdown field for dry oxides on p-4H-SiC is higher than the average field for wet oxides (7.6MV/cm compared to 7.1MV/cm at room temperature). However, both breakdown fields are lower than the average value of 8.2MV/cm measured for wet oxide layers that were not passivated. The lower breakdown fields can be attributed to donor-like states that appear near the valence band edge during passivation.

A Large Reduction in Interface-State Density for MOS Capacitor on 4H-SiC (11-2 0) Face Using H2 and H2O Vapor Atmosphere Post-Oxidation Annealing

2002 ◽  
Vol 389-393 ◽  
pp. 1057-1060 ◽  
Author(s):  
Kenji Fukuda ◽  
Junji Senzaki ◽  
Mitsuhiro Kushibe ◽  
Kazutoshi Kojima ◽  
Ryouji Kosugi ◽  
...  
Keyword(s):  
Interface State ◽  
State Density ◽  
Interface State Density ◽  
Large Reduction ◽  
Mos Capacitor

Influence of Ambient, Gate Metal and Oxide Thickness on Interface State Density and Time Constant in MOSiC Capacitor

2008 ◽  
Vol 600-603 ◽  
pp. 735-738 ◽  
Author(s):  
Shinji Nakagomi ◽  
Kenta Sato ◽  
Shun Suzuki ◽  
Yoshihiro Kokubun
Keyword(s):  
Oxide Layer ◽  
Time Constant ◽  
Oxide Thickness ◽  
Interface State ◽  
State Density ◽  
Interface State Density ◽  
Oxide Semiconductor ◽  
Mos Capacitor ◽  
Conductance Technique ◽  
Ambient Gas

A metal-oxide-semiconductor (MOS) capacitor was fabricated using 4H-SiC epitaxial layer, and the interface state was evaluated in oxygen and hydrogen ambient under high-temperature conditions by the AC conductance technique. The relationships between interface state density (Dit), and corresponding time constant (tit) were obtained. Influences of oxide thickness and of gate metal (Pt or Al) were studied. Dit of Pt gate capacitor is influenced by ambient gas at higher temperature but Dit of Al gate capacitor is little affected by ambient gas. Dit of capacitor with thicker oxide layer tends to be lower than that of capacitor with thinner oxide layer. Interface states with larger time constant are decreased for hydrogen ambient comparing with oxygen ambient in the Pt gate capacitor.

Interfacial Properties of SiO2 Grown on 4H-SiC: Comparison between N2O and Wet O2 Oxidation Ambient

2006 ◽  
Vol 527-529 ◽  
pp. 979-982 ◽  
Author(s):  
Antonella Poggi ◽  
Francesco Moscatelli ◽  
Andrea Scorzoni ◽  
Giovanni Marino ◽  
Roberta Nipoti ◽  
...  
Keyword(s):  
Silicon Carbide ◽  
Silicon Dioxide ◽  
Conduction Band ◽  
Interface State ◽  
Growth Conditions ◽  
State Density ◽  
Interface State Density ◽  
Conduction Band Edge ◽  
Wet Oxidation ◽  
Better Than

Many investigations have been conducted on the growth conditions of SiO2 on SiC to improve the oxide quality and the properties of the silicon carbide-silicon dioxide interface. In this work a comparison between a wet oxidation and an oxidation in N2O ambient diluted in N2 is proposed. The interface state density Dit near the conduction-band edge of SiC has been evaluated by conventional C-V measurements obtaining results similar or better than the literature data. Furthermore, the slow trapping phenomena have been studied and preliminary results are reported.

SiO2/SiC Interface Properties on Various Surface Orientations

2002 ◽  
Vol 742 ◽  
Author(s):  
Hiroshi Yano ◽  
Taichi Hirao ◽  
Tsunenobu Kimoto ◽  
Hiroyuki Matsunami
Keyword(s):  
Conduction Band ◽  
Room Temperature ◽  
Interface State ◽  
State Density ◽  
Interface State Density ◽  
Band Edge ◽  
Conduction Band Edge ◽  
Interface Properties ◽  
Mos Capacitors ◽  
Channel Mobility

ABSTRACTThe interface properties of MOS capacitors and MOSFETs were characterized using the (0001), (1120), and (0338) faces of 4H-SiC. (0001) and (1120) correspond to (111) and (110) in cubic structure. (0338) is semi-equivalent to (100). The interface states near the conduction band edge are discussed based on the capacitance and conductance measurements of n-type MOS capacitors at a low temperature and room temperature. The (0338) face indicated the smallest interface state density near the conduction band edge and highest channel mobility in n-channel MOSFETs among these faces.

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.

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