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.

Improved Inversion Channel Mobility in Si-face 4H-SiC MOSFETs by Phosphorus Incorporation Technique

2010 ◽  
Vol 1246 ◽  
Author(s):  
Dai Okamoto ◽  
Hiroshi Yano ◽  
Shinya Kotake ◽  
Kenji Hirata ◽  
Tomoaki Hatayama ◽  
...  
Keyword(s):  
Conduction Band ◽  
Field Effect ◽  
Field Effect Transistors ◽  
Interface State ◽  
State Density ◽  
Interface State Density ◽  
Band Edge ◽  
Conduction Band Edge ◽  
Channel Mobility ◽  
Inversion Channel

AbstractWe propose a new technique to fabricate 4H-SiC metal–oxide–semiconductor field-effect transistors (MOSFETs) with high inversion channel mobility. P atoms were incorporated into the SiO2/4H-SiC(0001) interface by post-oxidation annealing using phosphoryl chloride (POCl3). The interface state density at 0.2 eV from the conduction band edge was reduced to less than 1 × 1011 cm−2eV−1 by the POCl3 annealing at 1000 °C. The peak field-effect mobility of 4H-SiC MOSFETs on (0001) Si-face processed with POCl3 annealing at 1000 °C was approximately 90 cm2/Vs. The high channel mobility is attributed to the reduced interface state density near the conduction band edge.

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.

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.

Passivation of Oxide Layers on 4H-SiC Using Sequential Anneals in Nitric Oxide and Hydrogen

2003 ◽  
Vol 786 ◽  
Author(s):  
J. R. Williams ◽  
T. Isaacs-Smith ◽  
S. Wang ◽  
C. Ahyi ◽  
R. M. Lawless ◽  
...  
Keyword(s):  
Nitric Oxide ◽  
High Temperature ◽  
Interface State ◽  
State Density ◽  
Interface State Density ◽  
Band Edge ◽  
Conduction Band Edge ◽  
Trap Energy ◽  
Order Of Magnitude ◽  
Interface Passivation

ABSTRACTThe interface passivation process based on post-oxidation, high temperature anneals in nitric oxide (NO) is well established for SiO2 on (0001) 4H-SiC. The NO process results in an order of magnitude or more reduction in the interface state density near the 4H conduction band edge. However, trap densities are still high compared to those measured for Si / SiO2 passivated with post-oxidation anneals in hydrogen. Herein, we report the results of studies for 4H-SiC / SiO2 undertaken to determine the effects of additional passivation anneals in hydrogen when these anneals are carried out following a standard NO anneal. After NO passivation and Pt deposition to form gate contacts, post-metallization anneals in hydrogen further reduced the trap density from approximately 1.5 × 1012 cm−2eV−1 to about 6 × 1011 cm−2eV−1 at a trap energy of 0.1 eV below the band edge for dry thermal oxides on both (0001) and (11–20) 4H-SiC.

Electrical Characteristics of RF Sputtered ZnO/HfO2 Interfaces in Transparent Thin Film Transistors

2015 ◽  
Vol 1792 ◽  
Author(s):  
Prem Thapaliya ◽  
Wenchao Lu ◽  
Rashmi Jha
Keyword(s):  
Thin Film ◽  
Conduction Band ◽  
Thin Film Transistor ◽  
Interface State ◽  
State Density ◽  
Interface State Density ◽  
Band Edge ◽  
Conduction Band Edge ◽  
Dc Current ◽  
The Impact

ABSTRACTIn this work, we have reported the interface characterization of rf sputtered ZnO/HfO2 in thin film transistor structure by dc current-voltage and admittance spectroscopy. The interface state density (Dit) of 1013 eV−1cm−2 was extracted from the Gp/ω vs ω plot was comparable to value obtained from the subthreshold behavior. The grain boundary trap density (NGB) of 9.12×1012 cm−2 was estimated using Levinson’s model. The interface state density distribution below the conduction band edge shows a decreasing trend with energy below the conduction band edge. We also studied the impact of introducing MgO interfacial layer between ZnO and HfO2 interface as an approach towards decreasing the interface state density.

scholarly journals Inversion channel mobility and interface state density of diamond MOSFET using N-type body with various phosphorus concentrations

2019 ◽  
Vol 114 (24) ◽  
pp. 242101 ◽  
Author(s):  
Tsubasa Matsumoto ◽  
Hiromitsu Kato ◽  
Toshiharu Makino ◽  
Masahiko Ogura ◽  
Daisuke Takeuchi ◽  
...  
Keyword(s):  
Interface State ◽  
State Density ◽  
Interface State Density ◽  
Channel Mobility ◽  
Inversion Channel
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