Density and microstructure of a-C thin films

Kumar, Prabhat; Gupta, Mukul; Deshpande, Uday; Phase, D. M.; Ganesan, V.; Stahn, J.

doi:10.1016/j.diamond.2018.03.008

Cited by 12 publications

(2 citation statements)

References 33 publications

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“…of sp 2 hybridized C states at higher T s . A shift in the feature a can be observed at higher energy side by 0.3 eV for the sample deposited at T s = 523 K. This shows that, in addition with reduced carbide contribution at higher T s , the sample deposited at T s = 523 K has different local structure compared to samples deposited at T s = 300 and 773 K. In addition, a faint feature b is observed at 286.4 eV, although the origin of this feature is yet not clear [50].…”

Section: Units)mentioning

confidence: 87%

Structural and magnetic properties of co-sputtered Fe0.8C0.2 thin films

Kumar

Reddy

Ganesan

et al. 2020

Phys. Rev. Materials

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We studied the structural and magnetic properties of Fe 0.8 C 0.2 thin films deposited by co-sputtering of Fe and C targets in a direct current magnetron sputtering (dcMS) process at a substrate temperature (T s ) of 300, 523, and 773 K. The structure and morphology were measured using x-ray diffraction (XRD), x-ray absorption nearedge spectroscopy (XANES) at Fe L and C K edges and atomic/magnetic force microscopy (AFM, MFM). An ultrathin (3-nm) 57 Fe 0.8C0.2 layer, placed between relatively thick Fe 0.8 C 0.2 layers was used to estimate Fe selfdiffusion taking place during growth at different T s using depth profiling measurements. Such 57 Fe 0.8C0.2 layer was also used for 57 Fe conversion electron Mössbauer spectroscopy (CEMS) and nuclear resonance scattering (NRS) measurements, yielding the magnetic structure of this ultrathin layer. We found from XRD measurements that the structure formed at low T s (300 K) is analogous to Fe-based amorphous alloy and at high T s (773 K), predominantly a Fe 3 C phase has been formed. Interestingly, at an intermediate T s (523 K), a clear presence of Fe 4 C (along with Fe 3 C and Fe) can be seen from the NRS spectra. The microstructure obtained from AFM images was found to be in agreement with XRD results. MFM results also agree well with NRS as the presence of multi-magnetic components can be clearly seen in the sample grown at T s = 523 K. The information about the hybridization between Fe and C, obtained from Fe L-and C K-edge XANES also supports the results obtained from other measurements. In essence, from this work, a possibility for experimental realization of Fe 4 C has been demonstrated. It can be anticipated that by further fine-tuning of the deposition conditions, even single-phase Fe 4 C can be realized which hitherto remains an experimental challenge.

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Section: Units)mentioning

confidence: 87%

Structural and magnetic properties of co-sputtered Fe0.8C0.2 thin films

Kumar

Reddy

Ganesan

et al. 2020

Phys. Rev. Materials

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“…Consequently, increase in the intensity of the feature a signifies presence In MFM profile, it is taken along the the diagonal of the images of higher fraction of sp 2 hybridized C states at higher T s . A shift in the feature a can be observed at higher energy side by 0.3 eV for the sample deposited at T s = 523 K. This shows that, in addition with reduced carbide contribution at higher T s , the sample deposited at T s = 523 K have different local structure compared to samples deposited at T s = 300 and 773 K. In addition, a faint feature b is observed at 286.4 eV, although origin of this feature is yet not clear [49].…”

Section: B Electronic Structurementioning

confidence: 88%

Structural and magnetic properties of co-sputtered Fe0.8C0.2 thin films

Kumar,

Reddy,

Ganesan

et al. 2019

Preprint

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We studied the structural and magnetic properties of Fe0.8C0.2 thin films deposited by cosputtering of Fe and C targets in a direct current magnetron sputtering (dcMS) process at a substrate temperature (Ts) of 300, 523 and 773 K. The structure and morphology was measured using x-ray diffraction (XRD), x-ray absorption near edge spectroscopy (XANES) at Fe L and C K-edges and atomic/magnetic force microscopy (AFM, MFM), respectively. An ultrathin (3 nm) 57 Fe0.8C0.2 layer, placed between relatively thick Fe0.8C0.2 layers was used to estimate Fe selfdiffusion taking place during growth at different Ts using depth profiling measurements. Such 57 Fe0.8C0.2 layer was also used for 57 Fe conversion electron Mössbauer spectroscopy (CEMS) and nuclear resonance scattering (NRS) measurements, yielding the magnetic structure of this ultrathin layer. We found from XRD measurements that the structure formed at low Ts (300 K) is analogous to Fe-based amorphous alloy and at high Ts (773 K), pre-dominantly a Fe3C phase has been formed. Interestingly, at an intermediate Ts (523 K), a clear presence of Fe4C (along with Fe3C and Fe) can be seen from the NRS spectra. The microstructure obtained from AFM images was found to be in agreement with XRD results. MFM images also agrees well with NRS results as the presence of multi-magnetic components can be clearly seen in the sample grown at Ts = 523 K. The information about the hybridization between Fe and C, obtained from Fe L and C K-edges XANES also supports the results obtained from other measurements. In essence, from this work, experimental realization of Fe4C has been demonstrated. It can be anticipated that by further fine-tuning the deposition conditions, even single phase Fe4C phase can be realized which hitherto remains an experimental challenge.

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