High responsivity near-infrared photodetectors in evaporated Ge-on-Si

Sorianello, Vito; Iacovo, Andrea De; Colace, Lorenzo; Fabbri, Andrea; Tortora, Luca; Buffagni, E.; Assanto, Gaetano

doi:10.1063/1.4747213

Cited by 32 publications

(27 citation statements)

References 14 publications

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“…Owing to Ge's low absorption coefficient at near-infrared wavelength, however, light-absorbing layers with a total thickness of several micrometers are necessary, which require the Ge films to be grown on Si at high speed. So far, several growth techniques such as chemical vapor deposition (CVD), [4][5][6][7][8][9] vacuum evaporation (VE, including molecular beam epitaxy (MBE)), [10][11][12][13] and sputter epitaxy (SE) [14][15][16][17][18] have been applied to Ge epitaxy on Si. Among these techniques, SE takes advantage of surface bombardment by lowkinetic-energy particles, which enables epitaxy at low temperature, at high growth rate, and with high critical thickness.…”

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confidence: 99%

Sputter Epitaxial Growth of Flat Germanium Film with Low Threading-Dislocation Density on Silicon (001)

Yeh

Matsumoto

Sugihara

et al. 2014

ECS J. Solid State Sci. Technol.

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Fast epitaxy of Ge on Si(001) was realized by DC sputtering at 2.1 nm · s −1 and 360 • C; the resulting film was optically flat without a cross-hatch structure. After annealing at 700 • C, 90 • -full-edge dislocations dominated the Ge-Si interface and the threadingdislocation density (TDD) of the Ge film was below 10 4 cm −2 , which is three orders of magnitude lower than the value of Ge films prepared by other methods. The extremely low TDD might be attributable to the spaces vacated by desorbed Ar within the film that served as dislocation sinks during sputtering. Acceptor-band conduction, which was at 0.02 eV above the valence band and was induced by dislocations, was observed with a hole mobility of 3-10 cm 2 · V −1 · s −1 in the film prepared without annealing. After annealing at 700 • C, the ionized-defect scattering in the film was considerably decreased and a mobility of 1180 cm 2 · V −1 · s −1 was obtained. The direct band gap energy of the film prepared without annealing was 0.81 eV, and became 0.79 eV after annealing.

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confidence: 99%

Sputter Epitaxial Growth of Flat Germanium Film with Low Threading-Dislocation Density on Silicon (001)

Yeh

Matsumoto

Sugihara

et al. 2014

ECS J. Solid State Sci. Technol.

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“…23 Employing a sputtering technique, this compensation could be simply done by using n-doped sputter targets, without the need for an additional ex-situ doping step.…”

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confidence: 99%

Heteroepitaxial Ge-on-Si by DC magnetron sputtering

et al. 2013

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The growth of Ge on Si(100) by DC Magnetron Sputtering at various temperatures is studied by Spectroscopic Ellipsometry and Transmission Electron Microscopy. Smooth heteroepitaxial Ge films are prepared at relatively low temperatures of 380°C. Typical Stransky-Krastanov growth is observed at 410°C. At lower temperatures (320°C), films are essentially amorphous with isolated nanocrystallites at the Si-Ge interface. A minor oxygen contamination at the interface, developing after ex-situ oxide removal, is not seen to hinder epitaxy. Compensation of dislocation-induced acceptors in Ge by sputtering from n-doped targets is proposed

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“…The capability to detect tiny traces of chemical species within small areas (less than 0.01 mm 2 ), and with a depth resolution that approaches the nm, makes it a particularly suitable tool for the investigation of nmthick layers, such as our SFS heterostructures, in the search for anomalies at the interfaces between layers, 37 or for contaminants between and inside the layers.…”

Section: Tof-simsmentioning

confidence: 99%

Robustness of the0−πtransition against compositional and structural ageing in superconductor/ferromagnetic/superconductor heterostructures

et al. 2015

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We have studied the temperature induced 0 − π thermodynamic transition in Nb/PdNi/Nb Superconductor/Ferromagnetic/Superconductor (SFS) heterostructures by microwave measurements of the superfluid density. We have observed a shift in the transition temperature with the ageing of the heterostructures, suggesting that structural and/or chemical changes took place. Motivated by the electrodynamics findings, we have extensively studied the local structural properties of the samples by means of X-ray Absorption Spectroscopy (XAS) technique, and the compositional profile by Time-of-Flight Secondary Ion Mass Spectrometry (ToF-SIMS). We found that the samples have indeed changed their properties, in particular for what concerns the interfaces and the composition of the ferromagnetic alloy layer. The structural and compositional data are consistent with the shift of the 0 − π transition toward the behaviour of heterostructures with different F layers. An important emerging indication to the physics of SFS is the weak relevance of the ideality of the interfaces: even in aged samples, with less-than-ideal interfaces, the temperature-induced 0 − π transition is still detectable albeit at a different critical F thickness.

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High responsivity near-infrared photodetectors in evaporated Ge-on-Si

Cited by 32 publications

References 14 publications

Sputter Epitaxial Growth of Flat Germanium Film with Low Threading-Dislocation Density on Silicon (001)

Sputter Epitaxial Growth of Flat Germanium Film with Low Threading-Dislocation Density on Silicon (001)

Heteroepitaxial Ge-on-Si by DC magnetron sputtering

Robustness of the0−πtransition against compositional and structural ageing in superconductor/ferromagnetic/superconductor heterostructures

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