Structural, electronic structure, and band alignment properties at epitaxial NiO/Al2O3 heterojunction evaluated from synchrotron based X-ray techniques

Singh, S. D.; Nand, Mangla; Das, Arijeet; Ajimsha, R. S.; Upadhyay, Anand; Kamparath, Rajiv; Shukla, D. K.; Mukherjee, C.; Misra, Pankaj; K., S.; Sinha, A. K.; Jha, S. N.; Phase, D. M.; Ganguli, Tapas

doi:10.1063/1.4947500

Cited by 29 publications

(15 citation statements)

References 35 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…While GaAs has a band gap of 1.4 eV, [ 36 ] Al 2 O 3 is an ultra‐wide band gap dielectric with reported values for the band gap ranging from 7 up to 8.8 eV. [ 35,37–39 ] Figure 2d depicts a comparison of the decay constants τ obtained by exponential curve fittings (see Figure S3) for the E 2g Raman intensity of 2.5 ± 0.3‐nm‐thick h‐BN films transferred to GaAs, SiO 2 /Si, and Al 2 O 3 substrates. In comparison with SiO 2 /Si, longer and shorter time‐decay constants are, respectively, determined when Al 2 O 3 and GaAs are employed.…”

Section: Resultsmentioning

confidence: 99%

The impact of ultraviolet laser excitation during Raman spectroscopy of hexagonal boron nitride thin films

Karim

Lopes

Ramsteiner

2020

J Raman Spectroscopy

View full text Add to dashboard Cite

We utilized excitation in the ultraviolet (UV) spectral range for the study of hexagonal boron nitride (h-BN) thin films on different substrates by Raman spectroscopy. Whereas UV excitation offers fundamental advantages for the investigation of h-BN and heterostructures with graphene, the actual Raman spectra recorded under ambient conditions reveal a temporal decay of the signal intensity. The disappearance of the Raman signal is found to be induced by thermally activated chemical reactions with ambient molecules at the h-BN surface. The chemical reactions could be strongly suppressed under vacuum conditions which, however, favor the formation of a carbonaceous surface contamination layer. For the improvement of the signal-to-noise ratio under ambient conditions, we propose a line-scan method for the acquisition of UV Raman spectra in atomically thin h-BN, a material which is expected to play a key role in future technologies based on 2D van der Waals heterostructures.

show abstract

Section: Resultsmentioning

confidence: 99%

The impact of ultraviolet laser excitation during Raman spectroscopy of hexagonal boron nitride thin films

Karim

Lopes

Ramsteiner

2020

J Raman Spectroscopy

View full text Add to dashboard Cite

show abstract

“…However, this method applies high-energy pulses which may cause undesirable defects in the structure, and thereby change the electronic behavior of the films. PLD has been used to deposit various binary compounds [32][33][34][35][36][37][38][39][40][41][42][43][44][45][46][47].…”

Section: Introductionmentioning

confidence: 99%

Pulsed Laser Deposition of Rocksalt Magnetic Binary Oxides

et al. 2019

View full text Add to dashboard Cite

Magnetic binary oxides with the rocksalt structure constitute an important class of materials for potential applications as electronic or electrochemical devices. Moreover, they often become a theoretical playground, due to the simple electronic and crystal structures, in the quest for novel phenomena. For these possibilities to be realized, a necessary prerequisite would be to grow atomically ordered and controllably-strained binary oxides on proper substrates. Here we systematically explore the use of pulsed laser deposition technique (PLD) to grow three basic oxides that have rocksalt structure but different chemical stability in the ambient atmosphere: NiO (stable), MnO (metastable) and EuO (unstable). By tuning laser fluence FL, an epitaxial single-phase NiO thin-film growth can be achieved in a wide range of growth temperatures 10 ≤ TG ≤ 750 °C. At the lowest TG, the out-of-plane strain raises to 1.5%, which is five times higher than in NiO film grown at 750 °C. MnO thin films that had long-range order were successfully deposited on the MgO substrates after appropriate tuning of deposition parameters. The growth of MnO phase was strongly influenced by FL and the TG. EuO films with satisfactory quality were deposited by PLD after oxygen availability had been minimized. Synthesis of EuO thin films at rather low TG = 350 °C prevented thermally-driven lattice relaxation and allowed growth of strained films. Overall, PLD was a quick and reliable method to grow binary oxides with rocksalt structure in high quality that can satisfy requirements for applications and for basic research.Thin-film deposition is a technique that can be used to control strain in materials [22]. The Curie temperature TC of EuO thin film is strongly dependent on the strain and on film thickness tF [23]. Dislocations in NiO thin films locally change the magnetic ordering from antiferromagnetic to ferromagnetic [24]. Such 'ferromagnetic' dislocations originate from a local non-stoichiometry at in dislocation cores where Ni is deficient. A slight deviation from the stoichiometry also changes the conduction behavior in NiO thin films. Oxygendeficient EuO shows metallic behavior with a substantial increase of the TC to 120 K [25]. The deposition of high-quality magnetic binary oxides, and the ability to control the level of strain and density of defects in their structure, are challenging tasks in materials science and solid-state physics.Pulsed-laser deposition technique (PLD) has many advantages for growing thin films of high-quality oxides [26][27][28][29][30][31]. PLD can preserve the stoichiometry of the film composition,

show abstract

“…The prominent high‐energy characteristics near

h ν

= 856 eV and 873 eV indicate an increase in the proportion of Ni 3+ ions 20 . Some researchers reported that the increase in the Ni 3+ ions was caused by an increase in the number of Ni vacancies 21‐23 . Therefore, Ni‐A is a highly defective nickel oxide due to Ni vacancies, as shown in Figure 2D.…”

Section: Resultsmentioning

confidence: 97%

Synthesis of nonstoichiometric NiO nanocatalysts and growth of bamboo‐like carbon nanotubes

Kim

Lee

Park

et al. 2021

Int J Applied Ceramic Tech

View full text Add to dashboard Cite

The growth behavior of carbon nanotubes from NiO nanoparticles was investigated in terms of vacancy concentration and nanostructure. The NiO nanoparticles were prepared using anhydrous ethanol as a solvent to lower hydroxyl groups, compared to distilled water. The Ni vacancies in NiO via less hydrolysis were confirmed by lattice expansion and the increased mean oxidation state of Ni3+ through X‐ray absorption spectroscopy. The increased Ni3+ ratio determined from the photoelectron spectrum and ferromagnetism implied a high concentration of Ni vacancies on the surface. Nonstoichiometric NiO exhibited a small particle size of 10.13 nm and a narrow size distribution. For the growth of CNTs, the NiO nanocatalysts with vacancies resulted in thinner CNTs. The internal structures of the CNTs obtained from the defective particles were grown into bamboo‐like CNTs, identifying the variation in the carbon diffusion path.

show abstract

Structural, electronic structure, and band alignment properties at epitaxial NiO/Al2O3 heterojunction evaluated from synchrotron based X-ray techniques

Cited by 29 publications

References 35 publications

The impact of ultraviolet laser excitation during Raman spectroscopy of hexagonal boron nitride thin films

The impact of ultraviolet laser excitation during Raman spectroscopy of hexagonal boron nitride thin films

Pulsed Laser Deposition of Rocksalt Magnetic Binary Oxides

Synthesis of nonstoichiometric NiO nanocatalysts and growth of bamboo‐like carbon nanotubes

Contact Info

Product

Resources

About