Interfacial study and energy-band alignment of annealed Al2O3 films prepared by atomic layer deposition on 4H-SiC

Abstract

Al2O3 films were prepared by atomic layer deposition using trimethylaluminum and H2O at 250 °C on 4H-SiC substrates and annealed at 1000 °C in N2. The as-deposited and annealed Al2O3 films were measured and analyzed near the Al2O3/SiC interfaces by using an X-ray photoelectron spectroscopy (XPS) with etching processing. The XPS results showed that as-deposited Al2O3 films were O-rich and converted to anhydride Al2O3 films after annealed at 1000 °C in N2. Si suboxides were found both at as-deposited and annealed Al2O3/SiC interfaces. Energy band shift between Al2O3 and 4H-SiC was found after annealing. The conduction band offsets of as-grown and annealed Al2O3/SiC were 1.90 and 1.53 eV, respectively. These results demonstrated that Al2O3 can be a good candidate to be applied in SiC metal-oxide-semiconductor devices.

Negative charge trapping effects in Al2O3 films grown by atomic layer deposition onto thermally oxidized 4H-SiC

“…4 In regards to the physical and applicative issues, a common literature finding 9 has been the high leakage current attributed to a theoretical Al 2 O 3 /4H-SiC band offset value (∆E C = 1.5-1.7 eV 10,11 ), lower with respect to that of the SiO 2 /4H-SiC system (∆E C = 2.7 eV). 12,13 The experimental Al 2 O 3 /4H-SiC band offset value is typically even lower (∆E C ∼ 2eV 5,[14][15][16] ). For those reasons, some reports suggested the introduction of a thin thermally grown SiO 2 interfacial layer, in order to increase the conduction/valence band offset between the insulator and the SiC substrate.…”

“…Aluminum oxide (Al 2 O 3 ) can be an appropriate candidate as gate insulator for SiC, due to its high dielectric constant (κ ∼ 9), good thermal stability, relatively large band gap (∼ 9 eV) and high critical electric field (10 MV/cm). 5 As a matter of fact, in the last decade, Al 2 O 3 thin films have been already proposed as an alternative insulator to SiO 2 for SiC 6,7 and several methods have been used for their fabrication. Among them the Atomic Layer Deposition (ALD) technique is one of the more appealing because it provides a layer-by-layer growth, allowing an accurate control of the interfaces and conformal coverage.…”

Electrical characterization of amorphous Al2O3 dielectric films on n-type 4H-SiC

“…[8][9][10][11][12][13][14] One of the alternatives is aluminum oxide (Al 2 O 3 ) with bandgap of ∼ 7.0 eV. 8,11,15 Recently, an amorphous Al 2 O 3 has been used as a gate dielectric in graphene field effect transistors with some success. 16,17 Those Al 2 O 3 films are grown by atomic layer deposition (ALD) at 300 • C or thermal evaporation of metallic Al followed by low temperature oxidation to form Al 2 O 3 .…”

High-responsivity SiC Ultraviolet Photodetectors with SiO2 and Al2O3 Films

“…Atomic layer deposition (ALD) is a special chemical vapor deposition that is widely applied in microelectronic and optoelectronic fields to deposit oxides, nitrides, metals, etc [21][22][23]. As illustrated in Figure 7, the precursors and oxidants are pulsed into the chamber successively to deposit on the surface of the substrates monolayer by monolayer and cleaned by inert gases such as nitrogen during the deposition.…”