Investigation of Interface States on Mbe CoSi2/Si Schottky Contacts by Forward Bias Capacitance Measurement

1987 ◽  
Vol 91 ◽  
Author(s):  
H. Y. Chen ◽  
Y. C. Kao ◽  
Y. J. Mii ◽  
K. L. Wang
Keyword(s):  
Conduction Band ◽  
Density Of States ◽  
Forward Bias ◽  
Interface State ◽  
Interface States ◽  
Band Edge ◽  
Conduction Band Edge ◽  
Capacitance Measurement ◽  
Electron Capture Cross Section ◽  
State Band

ABSTRACTThe properties of the interface states of MBE grown CoSi2/n-Si(111) intimate contacts has been investigated using forward bias capacitance measurement. The barrier height øbn for this structure is 0.66±0.01 V. It has been found that there is an interface state band located in 0.44–0.50 eV bfow the conduction band edge of Si. The density of states D it is about 4×1012 cm−2 eV−1, lower than those made by other methods. This intrface state band is in equilibrium with Si and the charge exchange occurs mainly with the electrons in the conduction band of Si. The electron capture cross section oa is about 3×10−15 cm2 . In addition, some discrete interface states were found at 0.53 eV, 0.51 eV and 0.47 eV below the conduction band edge of Si, respectively for several samples. The density of states D it ranges (1.5–3.5)×1010 cm−2 . They are probably caused by localized point defects formed during CoSi2 growth.

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.

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.

Accuracy of the Energy Distribution of the Interface States at the SiO2/SiC Interface by Conductance Method

2016 ◽  
Vol 858 ◽  
pp. 437-440
Author(s):  
Munetaka Noguchi ◽  
Toshiaki Iwamatsu ◽  
Hiroyuki Amishiro ◽  
Hiroshi Watanabe ◽  
Shuhei Nakata ◽  
...  
Keyword(s):  
Energy Level ◽  
Energy Distribution ◽  
Conduction Band ◽  
Interface States ◽  
Oxide Semiconductor ◽  
Band Edge ◽  
Conduction Band Edge ◽  
Electrical Characteristics ◽  
Conductance Method ◽  
Effect Transistor

The electrical characteristics of the SiC metal-oxide-semiconductor field effect transistor (MOSFET) have been limited by large amount of states at the SiO2/SiC interface. In this study, the accuracy of the energy level of the interface states extracted by hypothetical high frequency extreme, which is conventionally used, is experimentally examined. Conductance measurements at low temperature between 65 K and 100 K reveal that the extracted energy distribution of the interface states at nitrided SiO2/SiC interface close to the conduction band edge depends on the measurement temperature. It is demonstrated that conductance method at 65K enables us more accurate evaluation of the interface states at the SiO2/SiC interface and found that the interface states density (Dit) of nitride SiO2/SiC interface is over 1013 cm-2eV-1 at energy level of 0.1 eV below the conduction band edge.

The Density of States in a-Si:C:H Revealed by Electrophotography

1993 ◽  
Vol 297 ◽  
Author(s):  
R.A.C.M.M. Van Swaaij ◽  
W.P.M. Willems ◽  
J. Bezemer ◽  
M.B. Von Der Linden ◽  
W.F. Van Der Weg
Keyword(s):  
Conduction Band ◽  
Density Of States ◽  
Carbon Concentration ◽  
Band Edge ◽  
Conduction Band Edge ◽  
Temperature Dependent ◽  
Energy Position ◽  
A Value ◽  
Dark Decay ◽  
Bulk Space

Electrophotographic dark decay measurements have been used to determine the surface density of states (SDOS) of a-Si:C:H. Injection of trapped charge from these deep states into the conduction band governs the dark discharge of a photoconductor, provided bulk generation and bulk space charge are negligible. It is found that the SDOS profiles peak around 0.60 eV below the conduction band for materials with different carbon concentration. This observation implies that the energy position of these states is fixed with respect to the conduction band edge, even though the optical band gap of these materials increases with increasing carbon concentration. The nature of these states may be ascribed to D− states, whose density is strongly enhanced by filling D° states when the material is charged negatively. Furthermore, we observed that the SDOS around 0.60 eV below the conduction band edge is approximately the same for materials with up to 8 at.% carbon. From temperature dependent measurements a value of 2·108 s−1 was obtained for the attempt-to-escape frequency.

Characterization of Localized Density of States in Intrinsic a-Si and poly-Si Films by Transient Voltage Spectroscopy

1995 ◽  
Vol 377 ◽  
Author(s):  
G. Kawachi ◽  
M. Ishii ◽  
T. Tanaka ◽  
N. Konishi
Keyword(s):  
Conduction Band ◽  
Density Of States ◽  
Band Edge ◽  
Conduction Band Edge ◽  
High Impedance ◽  
Pool Model ◽  
Transient Voltage ◽  
Mis Diode ◽  
Si Films

ABSTRACTThe localized density of states (LDOS) at interfaces between intrinsic silicon and silicon nitride (Si3N4 films are studied using transient voltage spectroscopy (TVS). In the TVS technique, the transient of the voltage across a MIS-diode after a trap filling voltage pulse is measured using a high-impedance voltage probe. This allows us to make a precise measurement of the LDOS at undoped Si/insulator interfaces. The LDOS in a-Si:H/Si3N4systems has a broad peak around the energy of 0.9 eV below the conduction-band edge. A modification of the LDOS at a-Si:H/Si3N4 interfaces by bias-annealing is clearly observed using this technique. The results are consistent with the defect pool model. The LDOS in laser annealed poly-Si/Si3N4 systems has a peak centered 0.6eV below the conduction-band edge, which seems to be the Si dangling bond states in the poly-Si films.

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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