Physical characterization of thin ALD–Al2O3 films

Jakschik, S.; Schroeder, Uwe; Hecht, T.; Krueger, Dietmar; Dollinger, G.; Bergmaier, A.; Luhmann, Claudia; Bartha, Johann W.

doi:10.1016/s0169-4332(03)00264-2

Cited by 76 publications

(55 citation statements)

References 10 publications

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“…The depletion of hydrogen from the Al 2 O 3 / c-Si interface likely contributes to the decrease of the surface passivation by Al 2 O 3 after firing. 2,18,19 Furthermore, the structural changes of the Al 2 O 3 will render the influence of the firing step irreversible.…”

mentioning

confidence: 99%

Stability of Al2O3 and Al2O3/a-SiNx:H stacks for surface passivation of crystalline silicon

Dingemans

Engelhart²,

Seguin³

et al. 2009

Journal of Applied Physics

149

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The thermal and ultraviolet (UV) stability of crystalline silicon (c-Si) surface passivation provided by atomic layer deposited Al2O3 was compared with results for thermal SiO2. For Al2O3 and Al2O3/a-SiNx:H stacks on 2 Ω cm n-type c-Si, ultralow surface recombination velocities of Seff<3 cm/s were obtained and the passivation proved sufficiently stable (Seff<14 cm/s) against a high temperature “firing” process (>800 °C) used for screen printed c-Si solar cells. Effusion measurements revealed the loss of hydrogen and oxygen during firing through the detection of H2 and H2O. Al2O3 also demonstrated UV stability with the surface passivation improving during UV irradiation.

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mentioning

confidence: 99%

Stability of Al2O3 and Al2O3/a-SiNx:H stacks for surface passivation of crystalline silicon

Dingemans

Engelhart²,

Seguin³

et al. 2009

Journal of Applied Physics

149

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“…Here, it is obvious that Al 2 O 3 is not an efficient diffusion barrier for Si. Jakschik et al 10 observed a similar behavior upon annealing Al 2 O 3 deposited on silicon expecting Si diffusion along the grain boundaries. The carbon profile ͑not shown͒ was not affected by heat treatments even above the crystallization temperature ͑900°C͒.…”

mentioning

confidence: 73%

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

Avice

Diplas

Thøgersen

et al. 2007

Applied Physics Letters

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Al 2 O 3 films with different thicknesses have been deposited on n-type ͑nitrogen-doped͒ 4H-SiC͑0001͒ epitaxial samples by atomic layer chemical vapor deposition at 300°C and subsequently annealed in Ar atmosphere at temperatures up to 1000°C. The Al 2 O 3 /4H-SiC structures were analyzed by x-ray photoelectron spectroscopy ͑XPS͒, secondary ion mass spectrometry ͑SIMS͒, and transmission electron microscopy ͑TEM͒. The XPS and SIMS results indicate that the average composition in the wider interface area does not significantly change due to the annealing. However, as revealed by the TEM investigations in combination with XPS, the as-grown samples exhibit a double interface created by an intermediate suboxide SiO Because of its wide band gap ͑ϳ3.2 eV for polytype 4H͒, SiC is suitable for applications related to high power, high frequency, and high temperatures. In recent years, investigations for alternative dielectrics for device applications have become of great interest. Al 2 O 3 is one of the few pure metal oxides exhibiting a high dielectric constant ͑ ϳ 10͒, a relatively wide band gap ͑E g ϳ 6.2 eV͒, and a good thermal stability; moreover, compared to ZrO 2 or HfO 2 it displays higher conduction and valence band offsets, ⌬E c = 1.7 eV and ⌬E v = 1.2 eV, relative to 4H-SiC. 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, 4-6 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 . 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. An ultimate goal is to correlate the structural and compositional properties of the interface with the previously reported electrical characteristics.The Al 2 O 3 layers have been grown by ALCVD on Sifaced, n-type 4H-SiC samples with a 10 m thick epilayer ͑net doping level of 2 ϫ 10 15 cm −3 ͒ on a highly doped substrate ͑net doping level of 1 ϫ 10 18 cm −3 ͒, oriented 8°off the ͑0001͒ direction, purchased from Cree, Inc. 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 treatm...

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“…The H concentration increased significantly at the interface probably due to H diffusion whilst the Si profile showed an out-diffusion after annealing at 1273 K indicating that Al 2 O 3 is not a diffusion barrier for Si in agreement with literature reports of Al 2 O 3 deposited on Si. [19] The C profile was not affected by temperature treatment even above crystallization temperature (T > 1173 K).…”

Section: Methodsmentioning

confidence: 90%

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

Diplas

Avice

Thøgersen

et al. 2008

Surface & Interface Analysis

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Al 2 O 3 films deposited on 4H-SiC(0001) by atomic layer deposition (ALD) were characterized by XPS, and high-resolution transmission electron microscopy (HRTEM). The effect of medium and high temperature (873, 1273 K) annealing on samples with oxide thicknesses of 5-8 and 100-120 nm was studied. XPS indicated the presence of a thin (∼1 nm) SiO x layer on the as-grown samples which increased to ∼3 nm after annealing above crystallization temperature (1273 K) in Ar atmosphere. Upon annealing the stoichiometry of the interfacial oxide approaches that of SiO 2 . HRTEM showed that the thickness of the interfacial oxide formed after annealing at 1273 K was not uniform. No significant increase in the thickness of the interfacial oxide, was observed after annealing at 873 K in a N 2 (90%)/H 2 (10%) atmosphere.

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Physical characterization of thin ALD–Al2O3 films

Cited by 76 publications

References 10 publications

Stability of Al2O3 and Al2O3/a-SiNx:H stacks for surface passivation of crystalline silicon

Stability of Al2O3 and Al2O3/a-SiNx:H stacks for surface passivation of crystalline silicon

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

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

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Physical characterization of thin ALD–Al2O3 films

Cited by 76 publications

References 10 publications

Stability of Al2O3 and Al2O3/a-SiNx:H stacks for surface passivation of crystalline silicon

Stability of Al2O3 and Al2O3/a-SiNx:H stacks for surface passivation of crystalline silicon

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

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

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