Improved Interface Trap Density Close to the Conduction Band Edge of a-Face 4H-SiC MOSFETs Revealed Using the Charge Pumping Technique

2017 ◽  
Vol 897 ◽  
pp. 143-146 ◽  
Author(s):  
Gerald Rescher ◽  
Gregor Pobegen ◽  
Thomas Aichinger ◽  
Tibor Grasser
Keyword(s):  
Silicon Carbide ◽  
Conduction Band ◽  
State Density ◽  
Trap Density ◽  
Band Edge ◽  
Conduction Band Edge ◽  
Power Mosfets ◽  
Charge Pumping ◽  
Wide Range ◽  
Reduced Mobility

We study the interface properties of 4H silicon carbide Si-face 0001 and a-face 11220 power MOSFETs using the charge pumping technique. MOSFETs produced on the a-face show a higher electron mobility than Si-face devices, although their charge pumping signal is 5 times higher, indicating a higher interface/border trap density. We show the main contribution to the interface/border trap density on a-face devices originates from deep states in a wide range around midgap, whereas Si-face devices show a higher and exponentially increasing interface/border state density close to the conduction band edge of 4H silicon carbide, resulting in reduced mobility.

Comment, on "A 1/f noise technique to extract the oxide trap density near the conduction band edge of silicon" [with reply]

1993 ◽  
Vol 40 (3) ◽  
pp. 680 ◽  
Author(s):  
C. Surya ◽  
T.Y. Hsiang ◽  
B.J. Gross ◽  
R. Jayaraman ◽  
C.G. Sodini
Keyword(s):  
Conduction Band ◽  
Trap Density ◽  
Band Edge ◽  
Conduction Band Edge ◽  
Oxide Trap

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.

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.

scholarly journals 4H-SiC Power VDMOSFET Manufacturing Utilizing POCl3 Post Oxidation Annealing

2020 ◽  
Vol 1004 ◽  
pp. 559-564
Author(s):  
Yanrui Ju ◽  
Didier Bouvet ◽  
Roger Stark ◽  
Judith Woerle ◽  
Ulrike Grossner
Keyword(s):  
Electric Field ◽  
Conduction Band ◽  
Current Density ◽  
Trap Density ◽  
Band Edge ◽  
Conduction Band Edge ◽  
Interface Trap Density ◽  
Interface Trap ◽  
Power Mosfet ◽  
Interface Characteristics

A novel POCl3 post-oxidation annealing recipe was developed. The interface trap density (Dit) is extracted by the C-ΨS method close to conduction band edge. The performance of the POCl3-treated oxide has been analyzed based on current density-electric field (J-E) measurements. A comprehensive and practical 4H-SiC power VDMOSFET manufacturing traveler has been designed. The power MOSFET that was fabricated based on this traveler exhibits less than half of the on-resistance and shows improved interface characteristics compared to a similarly designed commercial power MOSFET.

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.

Where Would the Electronic States of a Small Graphite-Like Carbon Island Contribute to the SiC/SiO2 Interface State Density Distribution?

2006 ◽  
Vol 527-529 ◽  
pp. 1019-1022 ◽  
Author(s):  
Christoph Thill ◽  
Jan Knaup ◽  
Peter Deák ◽  
Thomas Frauenheim ◽  
Wolfgang J. Choyke
Keyword(s):  
Conduction Band ◽  
Electronic States ◽  
Interface State ◽  
State Density ◽  
Interface State Density ◽  
Band Edge ◽  
Conduction Band Edge ◽  
Valence Band Edge ◽  
High Resolution Microscopy ◽  
Experimental Detection Limit

The high density of interface electron traps in the SiC/SiO2 system, near the conduction band of 4H-SiC, is often ascribed to graphitic carbon islands at the interface, although such clusters could not be detected by high resolution microscopy. We have calculated the electronic structure of a model interface containing a small graphite-like precipitate of 19 carbon atoms, with a diameter of ~7 Å, corresponding to the experimental detection limit. The analysis of the density of states shows only occupied states in the band gap of 4H-SiC near the valence band edge, while carbon related unoccupied states appear only well above the conduction band edge.

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