Leakage current and charge trapping behavior in TiO2∕SiO2 high-κ gate dielectric stack on 4H-SiC substrate

Mahapatra, Rajat; Chakraborty, A.K.; Poolamai, N.; Horsfall, Alton B.; Chattopadhyay, Sanatan; Wright, N. G.; Coleman, Karl S.; Coleman, P. G.; Burrows, C. P.

doi:10.1116/1.2433976

Cited by 62 publications

(30 citation statements)

References 30 publications

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“…From the I − V measurements, the amorphous Al 2 O 3 thin films were found to sustain an electric field of 8.0 MV/cm with a leakage current density of ϳ10 −3 A / cm 2 . This electric field strength is higher than that of any high-dielectric material on 4H-SiC reported to date, [28][29][30][31][32][33] including AlN, HfO 2 , SiO 2 / HfO 2 , Gd 2 O 3 , oxidized Ta 2 Si, and SiO 2 / TiO 2 , and several other studies of Al 2 O 3 deposited by sputtering, 34 evaporation, 35 and ultravioletassisted ͑UV-assisted͒ ALD 36 techniques. These electrical results demonstrate the potential of thermal ALD Al 2 O 3 gate dielectrics as an alternative to the state-of-the-art thermal SiO 2 .…”

Section: Capacitance-voltage and Leakage Current Characteristicsmentioning

confidence: 51%

Engineering epitaxial γ-Al2O3 gate dielectric films on 4H-SiC

Tanner

Toney

Blom

et al. 2007

Journal of Applied Physics

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The formation of epitaxial γ-Al2O3 thin films on 4H-SiC was found to be strongly dependent on the film thickness. An abrupt interface was observed in films up to 200 Å thick with an epitaxial relationship of γ-Al2O3(111)‖4H-SiC(0001) and γ-Al2O3(44¯0)‖4H-SiC(112¯0). The in-plane alignment between the film and the substrate is nearly complete for γ-Al2O3 films up to 115 Å thick, but quickly diminishes in thicker films. The films are found to be slightly strained laterally in tension; the strain increases with thickness and then decreases in films thicker than 200 Å, indicating strain relaxation which is accompanied by increased misorientation. By controlling the structure of ultrathin Al2O3 films, metal–oxide–semiconductor capacitors with Al2O3 gate dielectrics on 4H-SiC were found to have a very low leakage current density, suggesting suitability of Al2O3 for SiC device integration.

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Section: Capacitance-voltage and Leakage Current Characteristicsmentioning

confidence: 51%

Engineering epitaxial γ-Al2O3 gate dielectric films on 4H-SiC

Tanner

Toney

Blom

et al. 2007

Journal of Applied Physics

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“…Both Al and Ta metal nucleation layers resulted in a decrease in mobility as much as 25%, while the use of a Ti seed resulted in an increase in mobility of 10-22%. 50,89,90 Shen et al 91 showed that the quantum-Hall effect (QHE) and pronounced Shubnikov-de Haas (SdH) oscillations could be observed at low temperatures in epitaxial graphene using a metal seeded ALD Al 2 O 3 gate dielectric. 1(b)].…”

Section: B Metal Seed Layersmentioning

confidence: 99%

Graphene functionalization and seeding for dielectric deposition and device integration

Garces

Gaskill

2012

Journal of Vacuum Science &Amp; Technology B, Nanotechnology and Microelectronics: Materials, Processing, Measurement, and Phen

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Graphene has recently attracted wide-spread attention because of its unique transport and physical properties that are appealing for a wide range of electronic applications. Integration with scalable high-κ dielectrics is important for the realization of graphene-based top-gated electronic devices, including next generation THz applications. Atomic layer deposition (ALD), a low temperature deposition method based on two separate self-limiting surface reactions, is a preferred technique to achieve high-quality, conformal, ultrathin dielectric films with precise control of thickness and chemical composition at the atomic scale. Unfortunately, ALD of oxides on graphene is hindered by the inertness of the graphene surface. To alleviate this graphene-oxide incompatibility, several different functionalization and seeding methods have recently been developed to render the graphene more susceptible to the ALD process of high-κ dielectrics including: ozone, wet chemical and fluorine pretreatments, low-k polymer seed, e-beam metal, and oxide seed layers. The ability of each approach to enable conformal, uniform high-κ dielectrics on graphene while maintaining its inherent transport properties for low power, high-frequency device applications is discussed.

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“…Previous work has yielded moderate success with HfO2, Al2O3 and TiO2 amongst other materials. A reduced interface trap density is observed albeit with increased gate leakage due to reduced bandgap (although this may be mitigated by a SiO2 buffer layer) [1][2][3][4]. 1 shows the trade-off between bandgap and dielectric constant in typical oxide materials used on 4H-SiC alongside the significantly increased value achieved in this work.…”

Section: Introductionmentioning

confidence: 68%