Ge-on-Si photonic devices for photonic-electronic integration on a Si platform

Ishikawa, Yasuhiko; Saito, Shinichi

doi:10.1587/elex.11.20142008

Cited by 29 publications

(28 citation statements)

References 80 publications

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“…Prior to dipping into the etchant, the Si cap layer was selectively removed in a 2.38% tetramethylammonium hydroxide (TMAH) solution at 70 °C for 5 min. As shown previously, 34) the EPD agrees well with the TDD determined by the plan-view TEM observation. A surface observation by atomic force microscopy (AFM) was used to determine the EPD.…”

Section: Methodssupporting

confidence: 89%

“…To evaluate the TDD, an EPD measurement was performed. As in our previous studies, 34,49) a mixture of CH 3 COOH (67 ml), HNO 3 (20 ml), HF (10 ml), and I 2 (32 mg) was used as the etchant to form etch pits on the Ge surface. Prior to dipping into the etchant, the Si cap layer was selectively removed in a 2.38% tetramethylammonium hydroxide (TMAH) solution at 70 °C for 5 min.…”

Section: Methodsmentioning

confidence: 99%

“…A TDD reduction is required for higher-performance photodetectors, because TDs unfavorably act as carrier generation centers in a reverse-biased pin junction to cause a large leakage current. 33,34) So far, several attempts to reduce the TDD of a Ge film have been carried out, including a high-temperature post-growth annealing 32) and a thick Si x Ge 1-x graded buffer layer on Si [35][36][37] as well as an aspect ratio trapping (ART) technique in combination with an epitaxial lateral overgrowth. [38][39][40][41] However, there exist several issues such as a significant dopant diffusion/Si-Ge intermixing in the high-temperature annealing and a poor optical coupling between the Ge photodetector and Si optical waveguide in the thick-buffer/ART techniques, as previously described in detail.…”

Section: Introductionmentioning

confidence: 99%

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Reduced threading dislocation density in a germanium epitaxial film coalesced on an arrayed silicon-on-insulator strip

Amin

Motomura

Hizawa

et al. 2022

Jpn. J. Appl. Phys.

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This paper reports a reduction in the threading dislocation density (TDD) of a Ge epitaxial film on a Si-on-insulator (SOI) wafer in terms of the Si-photonics device application. An array of submicron SOI strips is prepared as a patterned substrate, on which Ge is epitaxially grown by chemical vapor deposition. A continuous Ge film is formed by a coalescence of the adjacent Ge crystals on the arrayed SOI strip, while leaving semicylindrical voids on the exposed surface of the buried SiO2 layer between the strips. The TDD of the coalesced Ge film is reduced to 1.0±0.1×108 cm–2, which is approximately a half of 2.2±0.2×108 cm–2 for a Ge film on an unpatterned SOI. A transmission electron microscope observation reveals that the TDD reduction is derived from a downward bending of the dislocation toward the void. An accumulation of the dislocations at the strip sidewalls also contributes to the TDD reduction.

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Section: Methodssupporting

confidence: 89%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Reduced threading dislocation density in a germanium epitaxial film coalesced on an arrayed silicon-on-insulator strip

Amin

Motomura

Hizawa

et al. 2022

Jpn. J. Appl. Phys.

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“…In the past several decades, silicon (Si)-based microelectronic integrated circuits (ICs) have achieved abundant progress based on the scaling down rule following Moore’s law [ 1 ]. However, as the channel length of metal-oxide-semiconductor field-effect transistor (MOSFET) has approached ~10-nm technology nodes over the past decade [ 2 ], RC delay and thermal consumption of metal interconnects have become serious problems retarding further improvement of the performance of Si-based microelectronic ICs [ 3 ]. Silicon-based optoelectronic ICs, which incorporate microelectronics and optical devices [ 4 ], have been proposed as an effective way to break the bottleneck [ 5 ].…”

Section: Introductionmentioning

confidence: 99%

Room Temperature Electroluminescence from Tensile-Strained Si0.13Ge0.87/Ge Multiple Quantum Wells on a Ge Virtual Substrate

et al. 2016

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Direct band electroluminescence (EL) from tensile-strained Si0.13Ge0.87/Ge multiple quantum wells (MQWs) on a Ge virtual substrate (VS) at room temperature is reported herein. Due to the competitive result of quantum confinement Stark effect and bandgap narrowing induced by tensile strain in Ge wells, electroluminescence from Γ1-HH1 transition in 12-nm Ge wells was observed at around 1550 nm. As injection current density increases, additional emission shoulders from Γ2-HH2 transition in Ge wells and Ge VS appeared at around 1300–1400 nm and 1600–1700 nm, respectively. The peak energy of EL shifted to the lower energy side superquadratically with an increase of injection current density as a result of the Joule heating effect. During the elevation of environmental temperature, EL intensity increased due to a reduction of energy between L and Γ valleys of Ge. Empirical fitting of the relationship between the integrated intensity of EL (L) and injection current density (J) with L~Jm shows that the m factor increased with injection current density, suggesting higher light emitting efficiency of the diode at larger injection current densities, which can be attributed to larger carrier occupations in the Γ valley and the heavy hole (HH) valance band at higher temperatures.

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“…51,52,54,55, Ge is an indirect band-gap semiconductor, but a lot efforts are being made to convert it to a direct band-gap semiconductor by tensile-strain-engineering. 4,61,[82][83][84] The TMAH etching is useful to make a suspended bridge structure, because TMAH do not etch Ge at all regardless of the etching of Si of the order of 100 µm. 54,55,[64][65][66][67][68] In the structure of Fig.…”

Section: Novel Si Photonic Waveguidesmentioning

confidence: 99%

Si photonic waveguides with broken symmetries: applications from modulators to quantum simulations

Saito

Tomita

Sotto

et al. 2020

Jpn. J. Appl. Phys.

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Symmetries of waveguides determine fundamental properties of photons such as mode profiles, polarisation, and effective refractive indexes as well as practical properties affecting the propagation loss. Here, we review our recent progress on manipulating symmetries of silicon (Si) photonic waveguides. Starting from the strategic choice of Si-On-Insulator (SOI) wafer specifications, we established the process technologies to fabricate Si wire and slot waveguides with atomically-flat interfaces, defined by Si (111) planes. These waveguides have relatively low propagation loss (∼ 1 dB/cm), even though they were fabricated in a university line. By combining patterning and re-growth of deposited amorphous Si, we also fabricated an Si slot waveguide with a nano-meter-scale vertical oxide layer, which is useful for optical modulators and various sensing applications. We also fabricated a horizontal slot waveguide using our manually bonded double-SOI substrate. The self-limited alkali-wet-etching allowed us to pattern the bottom SOI layer on top of the top SOI layer, by properly designing the mask to align along the mirror asymmetric Si (110) surface, allowing to access to top and bottom SOI layers individually through connected multiple-fin arrays. The patterning technique can be readily applicable to the other platform such as Si/LiNbO 3 -hybrid wafers, and we discuss our design of electro-optic (EO) modulator towards zero-power consumptions. We also investigate photonic crystal waveguides with broken mirror symmetries. By manipulating the mismatch between adjacent photonic crystals across the waveguide made of line defects, we could continuously control the band gap of the photonic crystals. Moreover, the phase profiles of modes exhibited photonic graphene and poly-acetylene shapes, made of optical vortices with optical orbital angular momentum (OAM). This shows that the most energetically favourable configuration of a photonic material under the triangular lattice is topologically equivalent to an organic material. We discuss the potential for the photonic organic chemistry and possible applications in quantum technologies.

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Ge-on-Si photonic devices for photonic-electronic integration on a Si platform

Cited by 29 publications

References 80 publications

Reduced threading dislocation density in a germanium epitaxial film coalesced on an arrayed silicon-on-insulator strip

Reduced threading dislocation density in a germanium epitaxial film coalesced on an arrayed silicon-on-insulator strip

Room Temperature Electroluminescence from Tensile-Strained Si0.13Ge0.87/Ge Multiple Quantum Wells on a Ge Virtual Substrate

Si photonic waveguides with broken symmetries: applications from modulators to quantum simulations

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