Characterization of Ni thin films following thermal oxidation in air

Abstract

The authors study the thermal oxidation of nickel thin films (50 nm) fabricated by conventional thermal evaporation, resulting from annealing in air at 300, 325, 350, 400, and 700 C. The characterization is performed by x-ray diffraction, Raman spectroscopy, superconducting quantum interference device magnetometry, and scanning electron microscopy. These techniques show that the oxidation increases with annealing temperature. The formation of granular films of coexisting Ni and NiO is confirmed after annealing at 400 C. The magnetic measurements indicate coexisting ferromagnetism and antiferromagnetism, corresponding to Ni and NiO contributions. The magnetic hysteresis loops reveal exchange bias in the samples annealed at 235, 350, and 400 C due to the competition between the exchange interactions at the Ni/NiO interfaces.

Rock Salt Ni/Co Oxides with Unusual Nanoscale‐Stabilized Composition as Water Splitting Electrocatalysts

“…Raman spectra of the Ni x Co 1− x O nanoparticles with different Ni/Co ratios are shown in Figure a. The broad band in the range between 450 and 600 cm −1 with its maximum at around 500 cm −1 corresponds to the first order one‐phonon mode of NiO . In the spectra of Co‐containing nanoparticles additional peaks appear at 183, 462, and 653 cm −1 , attributed to CoO T 2 g , E g , and A 1 g phonon modes, respectively .…”

Effect of Li doping on conductivity and band gap of nickel oxide thin film deposited by spin coating technique

“…The Raman scattering is observed between the range of 200 cm −1 and 1400 cm −1 . The peaks obtained below 1200 cm −1 are due to the first and the second-order Raman scattering by the photons and the peak observed above 1200 cm −1 spectra are originated by scattering of two magnons [45]. The vibrations (568 cm −1 ), (783 cm −1 ), (1095 cm −1 ), and (1330 cm −1 ) corresponds to one photon longitudinal optical (1PLO), two-photon transverse optical (2PTO), two-photon longitudinal optical (2PLO), two-magnon (2 M) band associated with Ni 2+ −O 2− −Ni 2+ [46][47][48].…”

“…The vibrations (568 cm −1 ), (783 cm −1 ), (1095 cm −1 ), and (1330 cm −1 ) corresponds to one photon longitudinal optical (1PLO), two-photon transverse optical (2PTO), two-photon longitudinal optical (2PLO), two-magnon (2 M) band associated with Ni 2+ −O 2− −Ni 2+ [46][47][48]. Magnons are quantized excitations of electron spin waves occurring in magnetically ordered materials [45]. Scattering due to two-magnon occurs when the incoming laser and the excited charges subsequently return to the ground orbital emitting a scattered phonon [45,49] and cause excitation of pairs of spin fluctuations [49].…”

“…Magnons are quantized excitations of electron spin waves occurring in magnetically ordered materials [45]. Scattering due to two-magnon occurs when the incoming laser and the excited charges subsequently return to the ground orbital emitting a scattered phonon [45,49] and cause excitation of pairs of spin fluctuations [49]. The intensity of the Raman peaks is increased as the concentration of lithium-ion in the nickel oxide thin film increases, this is due to the decreased crystalline size when lithium is doped.…”

Nickel Film Deposition with Varying RF Power for the Reduction of Contact Resistance in NiSi

“…To achieve this, the quality and stability of the Ni film are also very important. Ni films can be deposited by various methods such as chemical vapor deposition (CVD), atomic layer deposition (ALD), sputtering, MBE, thermal evaporation, pulsed laser deposition, electroplating [15][16][17][18][19][20][21], etc. Among these techniques, vapor deposition through conventional sputtering still remains the most widely used process for metal film deposition.…”