Dopant-defect interactions in Ge: Density functional theory calculations

Chroneos, Alexander

doi:10.1016/j.mssp.2012.02.017

Cited by 8 publications

(6 citation statements)

References 72 publications

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“…Ab initio simulations show that clusters such as As 3 V, As 4 V, Sb 3 V, and Sb 4 V, where V is a vacancy, have negative formation energies with respect to the isolated constituents, suggesting that the formation of such defects is the reason for the donor deactivation. Such clusters have also been shown to form preferentially in Ge:As and Ge:Sb. − …”

Section: Resultsmentioning

confidence: 99%

Ultralow Resistivity Ge:Sb heterostructures on Si Using Hydride Epitaxy of Deuterated Stibine and Trigermane

Senaratne

Sims

et al. 2016

ACS Appl. Mater. Interfaces

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The nonconventional deuterated stibine (SbD3) compound has been used for the first time in combination with trigermane (Ge3H8) to produce hyper-doped Ge-on-Si films with carrier concentrations n > 10(20) cm(-3) and record-low resistivities ρ = 1.8 × 10(-4) Ω cm. The growth takes place on Ge and Ge1-xSix buffered Si(100) wafers at ultralow temperatures (∼330 °C) at which Sb diffusion is negligible, leading to extremely flat atomic profiles of the constituents. The Sb substitution in the Ge lattice is determined by RBS channeling and corroborated by high-resolution XRD, which also reveal a systematic increase in lattice constant vs concentration, as expected due to the incorporation of the larger Sb. High-resolution TEM illustrates defect-free monocrystalline structures with device-quality morphologies. The electrical characteristics of the samples are measured using Hall effect and resistivity measurements combined with contactless infrared ellipsometry and are found to be consistent with an extrapolation of the bulk Ge:Sb properties to the high carrier concentrations achieved in our films. The Sb/Ge ratio in the doped layers is approximately the same as that in the precursor reaction mixture, indicating a highly efficient Sb incorporation afforded by the compatible reactivity of the molecules employed in this study. The resultant films are attractive for next generation germanium technologies that require low-resistance n+ junctions or a Fermi level that approaches the direct gap minimum in the conduction band, which drastically enhances the optical emission efficiency of n-type Ge.

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Section: Resultsmentioning

confidence: 99%

Ultralow Resistivity Ge:Sb heterostructures on Si Using Hydride Epitaxy of Deuterated Stibine and Trigermane

Senaratne

Sims

et al. 2016

ACS Appl. Mater. Interfaces

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“…On the basis of the above scenarios the intentional substitution of divalent sulfur atoms into Ge via S(GeH 3 ) 2 is manifestly distinct from the uncontrolled incorporation of oxygen atoms in Ge, which is typically observed during growth and processing of Ge films and actually represents a common impurity in the material. Accordingly, the properties of oxygen and dioxygen impurities in Ge have been extensively studied both theoretically and experimentally, − and it has been established that oxygen atoms adopt interstitial positions when incorporated into a diamond-structure Ge lattice as isolated impurities. By analogy, sulfur might be expected to exhibit similar structure motifs to those of oxygen.…”

Section: Resultsmentioning

confidence: 99%

Molecular Strategies for Configurational Sulfur Doping of Group IV Semiconductors Grown on Si(100) Using S(MH₃)₂(M = Si,Ge) Delivery Sources: An Experimental and Theoretical Inquiry

et al. 2014

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We report a new doping protocol of pure Ge films grown on Si and related Si/ Sn materials based on S delivered from high reactivity hydride molecules S(MH 3 ) 2 (M = Si,Ge). The new doping strategy targets next generation semiconductor applications requiring enhanced IR optical performance as well as high-mobility field effect transistors fully integrated with silicon. To explore this paradigm, we first developed a practical and straightforward synthesis approach, which avoids the use of toxic starting materials and yields viable quantities of the title compounds. These were then used to carry out proof-of-concept low-temperature depositions of Ge/Si(100) and GeSn/Si(100) films, doped with "double donor" S atoms for the first time. These systems are characterized using standard materials science techniques via RBS, XTEM, SIMS, and XRD for structure, composition, and crystallinity, and their electrical properties are measured by the Hall method. Thermally robust dopant levels <10 18 are systematically obtained using a range of process protocols, which can be further optimized for practical applications. Complementary first-principles density functional theory simulations were then used to study the stability and strain associated with the incorporation of S within the parent lattice as molecular fragments such as Ge−S−Ge, Ge−S, Si−S−Si, and Si−S derived from the S(SiH 3 ) 2 and S(GeH 3 ) 2 molecular sources. Completely incorporated Ge−S−Ge or Ge−S units in Ge in which S resides in either substitutional (tetrahedral) or near-substitutional (3-coordinate) sites are predicted to be strongly bound (−2.36 eV and −1.49 eV, respectively) relative to interstitial S and isolated Ge vacancies, while the corresponding binding in Si− S−Si and Si−S analogs is slightly enhanced. By considering the induced lattice strain, binding energy, and the structural accommodation of molecular core bonds, plausible defect-clusters are identified and tentatively used to correlate sulfur concentrations and carrier concentrations trends. In the case of the S(GeH 3 ) 2 grown films, a mixture of deep and shallow donor centers must be invoked to account for the observed carrier concentration enhancement.

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“…Chroneos et al have shown that V-D n complexes in Ge are thermodynamically stable at temperatures lower than 800 K. 41,42 According to density functional theory calculations, at temperatures higher than 850 K, the concentration of V-D 4 clusters progressively decreases liberating unbounded V and donor atoms. 41,42 Recently, we have shown that ultradoped n-type Ge with an electron concentration in the range of 10 20 cm −3 or higher can be achieved by applying nonequilibrium methods, e.g., low-energy plasma-enhanced chemical vapor deposition or ion implantation followed by millisecond-range flashlamp annealing (FLA) 14,26 where the maximum carrier concentration increases with decreasing the thickness of the doped layer. Most probably, it is due to the dissociation of V-D n complexes during millisecond range annealing.…”

Section: Journal Of Applied Physicsmentioning

confidence: 99%

Nanoscale n++-p junction formation in GeOI probed by tip-enhanced Raman spectroscopy and conductive atomic force microscopy

Prucnal

Berencén

Wang

et al. 2019

Journal of Applied Physics

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Ge-on-Si and Ge-on-insulator (GeOI) are the most promising materials for the next-generation nanoelectronics that can be fully integrated with silicon technology. To this day, the fabrication of Ge-based transistors with a n-type channel doping above 5 × 10 19 cm −3 remains challenging. Here, we report on n-type doping of Ge beyond the equilibrium solubility limit (n e ≈ 6 × 10 20 cm −3 ) together with a nanoscale technique to inspect the dopant distribution in n ++ -p junctions in GeOI. The n ++ layer in Ge is realized by P + ion implantation followed by millisecond-flashlamp annealing. The electron concentration is found to be three times higher than the equilibrium solid solubility limit of P in Ge determined at 800°C. The millisecond-flashlamp annealing process is used for the electrical activation of the implanted P dopant and to fully suppress its diffusion. The study of the P activation and distribution in implanted GeOI relies on the combination of Raman spectroscopy, conductive atomic force microscopy, and secondary ion mass spectrometry. The linear dependence between the Fano asymmetry parameter q and the active carrier concentration makes Raman spectroscopy a powerful tool to study the electrical properties of semiconductors. We also demonstrate the high electrical activation efficiency together with the formation of ohmic contacts through Ni germanidation via a single-step flashlamp annealing process.

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Dopant-defect interactions in Ge: Density functional theory calculations

Cited by 8 publications

References 72 publications

Ultralow Resistivity Ge:Sb heterostructures on Si Using Hydride Epitaxy of Deuterated Stibine and Trigermane

Ultralow Resistivity Ge:Sb heterostructures on Si Using Hydride Epitaxy of Deuterated Stibine and Trigermane

Molecular Strategies for Configurational Sulfur Doping of Group IV Semiconductors Grown on Si(100) Using S(MH₃)₂(M = Si,Ge) Delivery Sources: An Experimental and Theoretical Inquiry

Nanoscale n++-p junction formation in GeOI probed by tip-enhanced Raman spectroscopy and conductive atomic force microscopy

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Dopant-defect interactions in Ge: Density functional theory calculations

Cited by 8 publications

References 72 publications

Ultralow Resistivity Ge:Sb heterostructures on Si Using Hydride Epitaxy of Deuterated Stibine and Trigermane

Ultralow Resistivity Ge:Sb heterostructures on Si Using Hydride Epitaxy of Deuterated Stibine and Trigermane

Molecular Strategies for Configurational Sulfur Doping of Group IV Semiconductors Grown on Si(100) Using S(MH3)2(M = Si,Ge) Delivery Sources: An Experimental and Theoretical Inquiry

Nanoscale n++-p junction formation in GeOI probed by tip-enhanced Raman spectroscopy and conductive atomic force microscopy

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Molecular Strategies for Configurational Sulfur Doping of Group IV Semiconductors Grown on Si(100) Using S(MH₃)₂(M = Si,Ge) Delivery Sources: An Experimental and Theoretical Inquiry