Removal of dangling bonds and surface states on silicon (001) with a monolayer of selenium

Tao, Meng; Udeshi, Darshak; Basit, Nasir; Maldonado, Eduardo; Kirk, W. P.

doi:10.1063/1.1559418

Cited by 78 publications

(35 citation statements)

References 6 publications

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“…Further investigations are needed to clarify the detailed mechanism. As compared to the deposition of a Se monolayer between the metal and Si to change the SBH of the metal, [8][9][10] this method has several advantages. Selfaligned silicidation combined with S ion implantation can be easily used to fabricate nanometer MOSFETs.…”

Section: ͑ͻ10mentioning

confidence: 99%

“…Pure metals, like Mg, Al, Cr, and Ti, on Se-passivated n-Si͑001͒ showed very low and even negative SBH values which can be predicted by the Schottky-Mott theory. [8][9][10] However, deposition of these elements seems inappropriate for silicide contacts on Si due to the suppression of silicide formation. 10 In order to benefit from advantages of silicides in state-of-art MOSFET technology, methods to tune the SBH of silicides on Si are required.…”

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confidence: 99%

“…6 Lacharme et al 7 reported that surface states on Si can be removed by S exposure at room temperature. Tao et al [8][9][10] have used a monolayer of Se to eliminate the surface states on the Si͑001͒ surface by terminating dangling bond and relaxing strained bonds. Pure metals, like Mg, Al, Cr, and Ti, on Se-passivated n-Si͑001͒ showed very low and even negative SBH values which can be predicted by the Schottky-Mott theory.…”

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confidence: 99%

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Tuning of NiSi∕Si Schottky barrier heights by sulfur segregation during Ni silicidation

Zhao

Breuer

Rije

et al. 2005

Applied Physics Letters

135

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The Schottky barrier height ͑SBH͒ of NiSi on Si͑100͒ was tuned in a controlled manner by the segregation of sulfur ͑S͒ to the silicide/silicon interface. S was implanted into silicon prior to silicidation. During subsequent Ni silicidation, the segregation of S at the NiSi/ Si interface leads to the change of the SBH. The SBH of NiSi decreased gradually on n-Si͑100͒ from 0.65 eV to 0.07 eV and increased correspondingly on p-Si͑100͒. © 2005 American Institute of Physics. ͓DOI: 10.1063/1.1863442͔ Self-aligned silicidation is one of the key technologies in the state-of-art complementary metal-oxide-semiconductor ͑CMOS͒ process to make Ohmic or Schottky contacts at source/drain and gate. Amongst of them, NiSi silicide has emerged as a leading choice in Si nanometer electronics due to its low resistivity and high scalability. Recently, Schottky barrier source/drain metal-oxide-semiconductor field-effect transistors ͑MOSFETs͒ have been receiving a lot of attention because of the lower parasitic series resistance at source/ drain, possible zero junction depth and simpler fabrication process.1-4 However, for a typical Schottky barrier ͑SB͒ MOSFET, the on-current is limited by the tunneling through the Schottky barrier at the source. If a very low or a negative SBH could be realized, the on-current of SB-MOSFET could be increased substantially. 4 NiSi has an experimental SBH of 0.65 eV on n-Si͑100͒. This high SBH value hinders the application of NiSi in SB-MOSFETs. If we can lower the SBH of silicides to very low value, the device exhibits the same intrinsic performance as conventional MOSFET but also benefits from the advantages of SB-MOSFETs mentioned above.In an ideal metal-semiconductor system the SchottkyMott theory suggests that the SBH ͑⌽ B ͒ is simply determined by the difference between the work function of the metal ͑ M ͒ and the electron affinity of the semiconductor5 In practice, however, the presence of interface states leads to the SBH being less dependent on the metal work function. Dangling bonds at the semiconductor surface can be eliminated by valence-mending adsorbates. 6 S and Se are two possible valence-mending candidates for the Si͑100͒ surface.6 Lacharme et al. 7 reported that surface states on Si can be removed by S exposure at room temperature. Tao et al. [8][9][10] have used a monolayer of Se to eliminate the surface states on the Si͑001͒ surface by terminating dangling bond and relaxing strained bonds. Pure metals, like Mg, Al, Cr, and Ti, on Se-passivated n-Si͑001͒ showed very low and even negative SBH values which can be predicted by the Schottky-Mott theory.8-10 However, deposition of these elements seems inappropriate for silicide contacts on Si due to the suppression of silicide formation. 10 In order to benefit from advantages of silicides in state-of-art MOSFET technology, methods to tune the SBH of silicides on Si are required. In this paper we show an effective method to tune the SBH value of NiSi on both n-and p-type Si͑100͒. A small dose of S ions was implanted into Si before Ni de...

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Section: ͑ͻ10mentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

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Tuning of NiSi∕Si Schottky barrier heights by sulfur segregation during Ni silicidation

Zhao

Breuer

Rije

et al. 2005

Applied Physics Letters

135

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“…By terminating dangling bonds on the Si(100) surface, a low Schottky barrier close to 0 eV is expected between Al and n-type Si [11]. Figure 1 shows the I-V characteristics between two adjacent Al contacts on S-passivated n-type Si(100) surface at different temperatures.…”

Section: A Al/s-passivated N-type Si(100) Junctionsmentioning

confidence: 99%

Characterization of Al/Si junctions on Si(100) wafers with chemical vapor deposition-based sulfur passivation

et al. 2014

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Chemical vapor deposition based sulfur passivation using hydrogen sulfide is carried out on both n-type and p-typeSi(100) wafers. Al contacts are fabricated on sulfur-passivated Si(100) wafers and the resultant Schottky barriers are characterized with current-voltage (I-V), capacitance-voltage (C-V) and activation-energy methods. Al/S-passivated n-type Si (100) junctions exhibit ohmic behavior with a barrier height of less than 0.078 eV by the I-V method and significantly lower than 0.08 eV by the activation-energy method. For Al/S-passivated p-type Si(100) junctions, the barrier height is ~0.77 eV by I-V and activation-energy methods and 1.14 eV by the C-V method. The discrepancy between C-V and other methods is explained by image-force induced barrier lowering and edge-leakage current. The I-V behavior of an Al/S-passivated p-type Si(100) junction remains largely unchanged after 300°C annealing in air.It is also discovered that heating the S-passivated Si(100) wafer before Al deposition significantly improves the thermal stability of an Al/S-passivated n-type Si(100) junction to 500°C.

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“…Theoretical 5,6 and experimental [7][8][9] results showed that S or Se atoms are adsorbed in a bridge position on Si͑100͒. Tao et al 10,11 demonstrated that by passivating the Si͑100͒ surface with a monolayer of Se, the dangling bonds can be removed and nearly ideal Schottky barrier heights can be achieved using different metals. Use of a S or Secontaining solution is widespread for the passivation of the GaAs͑100͒ surface.…”

Section: Introductionmentioning

confidence: 99%

Effect of sulfur passivation of silicon (100) on Schottky barrier height: Surface states versus surface dipole

Ali¹,

Tao²

2007

Journal of Applied Physics

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Aluminum and nickel contacts were prepared by evaporation on sulfur-passivated n-and p-type Si͑100͒ substrates. The Schottky diodes were characterized by current-voltage, capacitance-voltage, and activation-energy measurements. Due to the passivation of Si dangling bonds by S, surface states are reduced to a great extent and Schottky barriers formed by Al and Ni on Si͑100͒ substrates show greater sensitivity to their respective work functions. Aluminum, a low work function metal, shows a barrier height of Ͻ0.11 eV on S-passivated n-type Si͑100͒ and ϳ0.80 eV on S-passivated p-type Si͑100͒, as compared to 0.56 and ϳ0.66 eV for nonpassivated n-and p-type Si͑100͒, respectively. Nickel, a high work function metal, shows ϳ0.72 and ϳ0.51 eV on S-passivated n and p-type Si͑100͒, respectively, as compared to ϳ0.61 and ϳ0.54 eV on nonpassivated n and p-type Si͑100͒, respectively. Though a surface dipole forms due to the adsorption of S on Si͑100͒, our experimental results indicate that the effect of surface states is the dominant factor in controlling the Schottky barrier height in these metal-Si systems.

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Removal of dangling bonds and surface states on silicon (001) with a monolayer of selenium

Abstract: Analysis of sub-stoichiometric hydrogenated silicon oxide films for surface passivation of crystalline silicon solar cells J. Appl. Phys. 112, 054905 (2012); 10.1063/1.4749415Thermal stability of ohmic contacts between Ti and Se-passivated n-type Si (001)

Cited by 78 publications

References 6 publications

Tuning of NiSi∕Si Schottky barrier heights by sulfur segregation during Ni silicidation

Tuning of NiSi∕Si Schottky barrier heights by sulfur segregation during Ni silicidation

Characterization of Al/Si junctions on Si(100) wafers with chemical vapor deposition-based sulfur passivation

Effect of sulfur passivation of silicon (100) on Schottky barrier height: Surface states versus surface dipole

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