Comparison of near-interface traps in Al2O3∕4H-SiC and Al2O3∕SiO2∕4H-SiC structures

Abstract

Aluminum oxide (Al2O3) has been grown by atomic layer deposition on n-type 4H-SiC with and without a thin silicon dioxide (SiO2) intermediate layer. By means of Capacitance Voltage and Thermal Dielectric Relaxation Current measurements, the interface properties have been investigated. Whereas for the samples with an interfacial SiO2 layer the highest near-interface trap density is found at 0.3 eV below the conduction band edge, Ec, the samples with only the Al2O3 dielectric exhibit a nearly trap free region close to Ec. For the Al2O3/SiC interface, the highest trap density appears between 0.4 to 0.6 eV below Ec. The results indicate the possibility for SiC-based MOSFETs with Al2O3 as the gate dielectric layer in future high performance devices.

Al2O3/SiO2 films prepared by electron-beam evaporation as UV antireflection coatings on 4H-SiC

“…The most widely used passivation for 4H-SiC devices is thermally grown oxide SiO 2 . Nevertheless, with higher dielectric constant and better thermal stability, Al 2 O 3 draws more and more attention as passivation and gate dielectric material on 4H-SiC devices in recent years [1][2][3]. In another respect, SiO 2 and Al 2 O 3 are the most important oxide film materials for optical coatings in the DUV spectral region [4,5].…”

Interfacial studies of Al2O3 deposited on 4H‐SiC(0001)

“…The latter was shown by TDRC measurements of 1273 K (Ar) annealed (∼100 nm) Al 2 O 3 /4H-SiC capacitors. [20] www.interscience.wiley.com/journal/sia …”

Rearrangement of the oxide-semiconductor interface in annealed Al2O3∕4H-SiC structures

“…In fact, annealing in Ar above the crystallization temperature ͑ϳ900°C͒ was found to significantly enhance the electrical properties of the Al 2 O 3 / SiC interface and promote formation of the ␥ phase of Al 2 O 3 . Furthermore, it has been revealed that the interface properties of those annealed structures are superior to the ones of SiO 2 /4H-SiC interfaces, since the density of electron traps close to the conduction band minimum is reduced, 4 as required for improved channel mobility in a metal-oxide-SiC field effect transistors. In this study, the Al 2 O 3 /4H-SiC interface was investigated on as-grown and annealed samples using angle resolved x-ray photoelectron spectroscopy ͑AR-XPS͒, transmission electron microscopy ͑TEM͒, and secondary ion mass spectrometry ͑SIMS͒.…”

“…1,2 It has been shown that high quality Al 2 O 3 films can be grown on SiC by atomic layer chemical vapor deposition ͑ALCVD͒. 3 In previous studies, [4][5][6] electrical characterization such as capacitancevoltage ͑CV͒ and thermal dielectric relaxation current measurements of Al 2 O 3 /4H-SiC capacitors were reported. In fact, annealing in Ar above the crystallization temperature ͑ϳ900°C͒ was found to significantly enhance the electrical properties of the Al 2 O 3 / SiC interface and promote formation of the ␥ phase of Al 2 O 3 .…”

“…Details of the cleaning and growth procedure can be found elsewhere. 4,5 For the AR-XPS measurements, 5 and 8 nm thick Al 2 O 3 layers were grown while thicker layers ͑ϳ110-120 nm͒ were deposited for the TEM and SIMS measurements. Annealing treatments have been carried out in Ar atmosphere at 1000°C for 15, 30, and 60 min.…”