Auger electron spectroscopy of super-doped Si:Mn thin films

Abe, Shinji; Nakasima, Y; Okubo, Susumu; Nakayama, Hiroshi; Nishino, Taneo; Yanagi, Hisao; Ohta, H.; Iida, Shoji

doi:10.1016/s0169-4332(98)00704-1

Cited by 10 publications

(6 citation statements)

References 14 publications

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“…Therefore, the non-equilibrium doping process is necessary to realize the high doping concentration. Silicons heavily doped with transition metal manganese at the doping levels more than 5% have been successful grown by using gas-source molecular beam epitaxy (GSMBE) [8,9] and laser-ablation molecular beam epitaxy (LAMBE) [10]. Hwa-Mok Kim et al reported on the growth of ferromagnetic Mn x Si 1Àx films by vacuum evaporation method, in which the Curie temperature of Mn 0.07 Si 0.93 is 21075 K [11].…”

Section: Introductionmentioning

confidence: 99%

Investigation of Mn-implanted n-Si by low-energy ion beam deposition

Liu

Chen

Song

et al. 2005

Journal of Crystal Growth

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Mn ions were implanted to n-type Si(0 0 1) single crystal by low-energy ion beam deposition technique with an energy of 1000 eV and a dose of 7.5 Â 10 17 cm À2 . The samples were held at room temperature and at 300 1C during implantation. Auger electron spectroscopy depth profiles of samples indicate that the Mn ions reach deeper in the sample implanted at 300 1C than in the sample implanted at room temperature. X-ray diffraction measurements show that the structure of the sample implanted at room temperature is amorphous while that of the sample implanted at 300 1C is crystallized. There are no new phases found except silicon both in the two samples. Atomic force microscopy images of samples indicate that the sample implanted at 300 1C has island-like humps that cover the sample surface while there is no such kind of characteristic in the sample implanted at room temperature. The magnetic properties of samples were investigated by alternating gradient magnetometer (AGM). The sample implanted at 300 1C shows ferromagnetic behavior at room temperature. r

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Section: Introductionmentioning

confidence: 99%

Investigation of Mn-implanted n-Si by low-energy ion beam deposition

Liu

Chen

Song

et al. 2005

Journal of Crystal Growth

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“…Techniques based on molecular beam epitaxy have been employed in order to highly dope Si with Mn ͑about 5%͒. 9, 10 Magnetron cosputtering has been used as well for the deposition of Mn-doped Si thin films 11 on Si substrates. The initial film is amorphous, whereas once annealed at 800°C it is single-phase polycrystalline with a room-temperature FM behavior.…”

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confidence: 99%

Mn-doped silicon nanowires: First-principles calculations

et al. 2008

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We present first-principles calculation of Mn-doped silicon nanowires. We discuss the energetics of both isolated point defects and Mn dimers, where a different behavior of the magnetization vs doping curve is predicted depending on the type of impurity. As a result of the broadening of the band gap, the range of doping condition that favors the stability of the substitutional Mn defect increases with respect to bulk. We also show that Mn dimers favor ferromagnetic alignment, discussing how the driving force to form aggregates has an essential role to stabilize ferromagnetism in the nanowires.

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“…1,2 Among the recent developments, it was shown that germanium 3 and silicon 4,5 can also be doped to a high Mn concentration, making them good candidates for spintronic applications. For example, using gas-source molecular beam epitaxy (MBE) on a Si͑001͒ substrate, up to 5 atomic percent Mn has been successfully incorporated into thin Si films at 300°C.…”

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confidence: 99%

Theory ofMnsupersaturation inSiandGe

2004

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Using first-principles total-energy methods, we calculate the formation energy for typical Mn defects in bulk Si and Ge and on (001) surfaces, from which the various Mn solubility limits are derived. Applying the theory for ultrahigh doping in semiconductors, we can understand why Mn solubility in epitaxially-grown Si and Ge films could be several atomic percent while the solid solubility limits are many orders of magnitude smaller. In particular, we suggest that hydrogen passivation of the surface during growth could be the key to such high solubilities.The recent study of ferromagnetic properties of transition metal doped III-V semiconductors have rekindled interest in dilute magnetic semiconductors. 1,2 Among the recent developments, it was shown that germanium 3 and silicon 4,5 can also be doped to a high Mn concentration, making them good candidates for spintronic applications. For example, using gas-source molecular beam epitaxy (MBE) on a Si͑001͒ substrate, up to 5 atomic percent Mn has been successfully incorporated into thin Si films at 300°C. 4 The internal magnetization of local Mn spins have also been observed by Hall measurement. Since Si is the backbone of the electronic industry, it is utterly important to develop group-IV based spintronics as integration with existing silicon technologies would be straightforward. Interestingly, however, the Mn solubility in these materials exceed far beyond the solid solubility limits, determined experimentally. 4 This raises the interesting question as to how such high solubility could be achieved. It is likely that epitaxial growth has an impact on the Mn incorporation. Without knowing the microscopic mechanism, however, it will be difficult, if not irrelevant, to predict the magnetic properties of the epitaxially grown thin films.In this paper, using first-principles total energy calculations, we have studied the Si: Mn and Ge: Mn systems. We find that for Si, Mn prefers the tetrahedral interstitial site in the bulk but substitutional site at (001) surfaces. For Ge, Mn prefers the interstitial site both in bulk and at surfaces. The differences in the defect types between Si and Ge can be explained in terms of the difference in the vacancy formation energy. Our calculated solid solubility limit for Si is in good agreement with experiment. Surface enhanced kinetic solubility limits were also considered but fall far short of the experimental values. We suggest instead that surface passivation, e.g., by hydrogen in gas-source MBE, could be the primary reason for the significantly enhanced Mn solubility in Si beyond the solid solubility limit.The calculations were performed using the densityfunctional theory within the generalized gradient approximation (GGA). 6 We used the Vanderbilt ultrasoft pseudopotentials 7 and the Vosko-Wilk-Nusair interpolation for the correlation functional in the spin-polarized calculations, as implemented by the plane-wave total energy VASP code. 8 The cutoff energy for the planewave expansion is 270 eV. For bulk defect calculations, we ...

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Auger electron spectroscopy of super-doped Si:Mn thin films

Cited by 10 publications

References 14 publications

Investigation of Mn-implanted n-Si by low-energy ion beam deposition

Investigation of Mn-implanted n-Si by low-energy ion beam deposition

Mn-doped silicon nanowires: First-principles calculations

Theory ofMnsupersaturation inSiandGe

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