Ultrathin Aluminum Oxide Gate Dielectric on N-Type 4H-SiC Prepared by Low Thermal Budget Nitric Acid Oxidation

Abstract

MOS capacitors with an ultrathin aluminum oxide (Al 2 O 3 ) gate dielectric were fabricated on n-type 4H-SiC. Al 2 O 3 was prepared by room-temperature nitric acid (HNO 3 ) oxidation of ultrathin Al film followed by furnace annealing. The effective dielectric constant of 9 4 and equivalent oxide thickness of 26 A are produced, and the interfacial layer and carbon clusters are not observed in this paper. The electrical responses of MOS capacitor under heating and illumination are used to identify the conduction mechanisms. For the positively biased case, the conduction mechanism is shown to be dominated by Schottky emission with an effective barrier height of 1 12 0 13 eV. For the negatively biased case, the gate current is shown to be due to the generation-recombination process in depletion region and limited by the minority carrier generation rate. The feasibility of integrating alternative gate dielectric on SiC by a low thermal budget process is demonstrated.

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

“…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 .…”

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

“…18 to other reported results for SiO 2 and alternative dielectrics on SiC MIS capacitors. 19,20 The effective dielectric constant and effective oxide thickness of the stack layer are found to be 24.5 and 15.8 nm, respectively, from accumulation capacitance. It should be mentioned here that there is a possibility of the formation of a thin interface layer between the gate electrode ͑Al͒ and the dielectric layer ͑TiO 2 ͒ which may affect the extraction of the actual dielectric constant of the stack layer.…”

Physical characterization of post-deposition annealed metal-organic decomposed cerium oxide film spin-coated on 4H-silicon carbide

“…One approach to overcome this is to replace the relatively low-k nitrided-SiO 2 with a gate oxide with higher k value [1]. Numerous high-k gate oxides, such as Al 2 O 3 [21][22][23][24], La 2 O 3 [25], HfO 2 [26][27][28], Gd 2 O 3 [29], AlN [30], and ZnO [31], have been deposited on SiC substrate to reduce the electric field in the oxides.…”