Ultralow dark current Ge/Si(100) photodiodes with low thermal budget

Osmond, Johann; Isella, Giovanni; Chrastina, D.; Kaufmann, R.; Acciarri, M.; Känel, H. von

doi:10.1063/1.3125252

Cited by 95 publications

(43 citation statements)

References 27 publications

(22 reference statements)

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“…In the 864x sample series, grown on [100] silicon wafers, the PH 3 flux was varied in percentage of its maximum value around 1 sccm. In the 933x series, the PH 3 flux was kept at 25% or 40% and three types of substrates were employed: (i) [100] germanium wafer for homo-epitaxial growth resulting in threading dislocation densities in the n-Ge films < 10 5 cm −2 ; (ii) [100] silicon wafers for hetero-epitaxial growth (due to the 4.2% difference between the lattice constants of Si and Ge) of fully relaxed n-Ge films with high dislocation densities of the order of 10 9 cm −2 ; (iii) the same [100] silicon wafers with a 2 µm thick undoped Ge layer (so-called virtual substrate) which is cyclically annealed between 600 and 780 o C to reduce the dislocation density down to 10 7 cm −2 before growing the n-doped film 35 . Indeed, heavily doped n-Ge films cannot be annealed at these temperatures because of the tendency of P atoms to form clusters 33 .…”

Section: Growth Of Heavily Doped Filmsmentioning

confidence: 99%

Tunability of the dielectric function of heavily doped germanium thin films for mid-infrared plasmonics

et al. 2016

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Heavily-doped semiconductor films are very promising for application in mid-infrared plasmonic devices because the real part of their dielectric function is negative and broadly tunable in this wavelength range. In this work we investigate heavily n-type doped germanium epilayers grown on different substrates, in-situ doped in the 10 17 to 10 19 cm −3 range, by infrared spectroscopy, first principle calculations, pump-probe spectroscopy and dc transport measurements to determine the relation between plasma edge and carrier density and to quantify mid-infrared plasmon losses. We demonstrate that the unscreened plasma frequency can be tuned in the 400 -4800 cm −1 range and that the average electron scattering rate, dominated by scattering with optical phonons and charged impurities, increases almost linearly with frequency. We also found weak dependence of losses and tunability on the crystal defect density, on the inactivated dopant density and on the temperature down to 10 K. In films where the plasma was optically activated by pumping in the near-infrared, we found weak but significant dependence of relaxation times on the static doping level of the film. Our results suggest that plasmon decay times in the several-picosecond range can be obtained in ntype germanium thin films grown on silicon substrates hence allowing for underdamped mid-infrared plasma oscillations at room temperature.The recent push towards applications of spectroscopy for chemical and biological sensing in the mid-infrared (mid-IR)1-8 has prompted the need for conducting thin films displaying values of the complex dielectric functionǫ(ω) = ǫ ′ (ω) + iǫ ′′ (ω) that can be tailored to meet the needs of novel electromagnetic designs exploiting the concepts of metamaterials, transformation optics and plasmonics 9 . In the design of metamaterials, where subwavelength sized conducting elements are embedded in dielectric matrices, if the values of ǫ ′ of the metal and the dielectric are of the same order, but have opposite sign, the geometric filling fractions of the metal and dielectric can be readily tuned to achieve subwavelengthresolution focusing of radiation 10 . Such requirement is met by silver for wavelengths λ around 400 nm. The same condition cannot be achieved in the IR range by using elemental metals, however, because metals possess an extremely high negative value of ǫ ′ not equaled, in

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Section: Growth Of Heavily Doped Filmsmentioning

confidence: 99%

Tunability of the dielectric function of heavily doped germanium thin films for mid-infrared plasmonics

et al. 2016

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“…The dark currents of the Ge FinLED are increased substantially compared with those of the Si FinLED, but the observed ultralow dark current density of 1.86 Â 10 À5 (3.41 Â 10 À3 ) A/cm 2 at the reverse bias of 1(5) V is comparable to those reported as the record low dark currents. 20 The forward currents of the Ge Fin LED are reduced compared with those of the Si FinLED, presumably because of the type II band alignment 8 at the Ge fin/Si electrode interface. Nevertheless, the forward current density of the Ge Fin LED can be extremely high, exceeding the values of 3.40 Â 10 3 (4.62 Â 10 5 ) A/cm 2 at the bias of 1(5) V without a breakdown.…”

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confidence: 99%

Germanium fin light-emitting diode

Saito

Oda

Takahama

et al. 2011

Applied Physics Letters

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We propose a germanium fin light-emitting diode for a monolithic light source on a Si photonics chip. The germanium fins were fabricated by the oxidation condensation of silicon-germanium sidewalls epitaxially grown on silicon fins. We found that a tensile stress is applied to the pure germanium fins by the difference of the thermal expansion coefficient with that of the surrounding oxide. The electroluminescence spectra were consistent with those expected from direct recombination in germanium with a tensile stress. The strong immunity of germanium fins against high current densities would be favourable to achieve population inversions by electrical pumping.

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“…The dark current is comparable to some of the best reported from Ge on Si photodetectors. 15 Both the photoluminescence (PL) and electroluminescence from the LED were measured using a Bruker Vertex 70v FTIR system. The FTIR system uses a calcium fluoride beamsplitter and a room temperature extended InGaAs detector, which can detect radiation between 0.8 and 2.5 lm.…”

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confidence: 99%

1.55 μm direct bandgap electroluminescence from strained n-Ge quantum wells grown on Si substrates

Gallacher

Velha

Paul

et al. 2012

Applied Physics Letters

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Design and optimization of a light-emitting diode projection micro-stereolithography three-dimensional manufacturing system Rev. Sci. Instrum. 83, 125001 (2012) Size-dependent efficiency and efficiency droop of blue InGaN micro-light emitting diodes Appl. Phys. Lett. 101, 231110 (2012) A bright cadmium-free, hybrid organic/quantum dot white light-emitting diode Appl. Phys. Lett. 101, 233110 (2012) Interplay of polarization fields and Auger recombination in the efficiency droop of nitride light-emitting diodes Appl. Phys. Lett. 101, 231107 (2012) Precise relationship between voltage and frequency at the appearance of negative capacitance in InGaN diodes

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Ultralow dark current Ge/Si(100) photodiodes with low thermal budget

Cited by 95 publications

References 27 publications

Tunability of the dielectric function of heavily doped germanium thin films for mid-infrared plasmonics

Tunability of the dielectric function of heavily doped germanium thin films for mid-infrared plasmonics

Germanium fin light-emitting diode

1.55 μm direct bandgap electroluminescence from strained n-Ge quantum wells grown on Si substrates

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