The Wonderful World of Designer Ge Quantum Dots

Wang, I-Hsiang; Hong, Po-Yu; Peng, Kang-Lin; Lin, Horng–Chih; George, T.; Li, Peiwen

doi:10.1109/iedm13553.2020.9372027

Cited by 4 publications

(11 citation statements)

References 4 publications

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“…Our extensive experimental observations show that the Ge-QDs appear to not only facilitate the decomposition of proximal Si-containing layers such as SiO 2 , Si 3 N 4 , and Si, but also in turn, mediate the regrowth of SiO 2 [22], densification of Si 3 N 4 [27,28], and the generation of SiGe nanosheets on Si [27,32,39]. Such deconstruction-construction processes dynamically occur as a result of the exquisite interplay between Ge, Si, and O interstitials during the thermal-oxidation process, pointing to ultimately achieving the ability to form self-organized heterostructures of Ge-QD/SiO 2 -shell on Si 3 N 4 and Ge-QD/SiO 2 -shell/SiGe-nanosheet on Si with precise control of the Ge-QD sizes and at the desired spatial locations.…”

Section: And Si During Thermal-oxidation Processmentioning

confidence: 94%

“…1). The Ge-QDs were created using the selective oxidation of poly-Si 1 − x Ge x lithographically patterned structures (for instance, pillars and islands) with specifically designed Si 3 N 4 layers on top [22][23][24] or at the sidewalls [25][26][27][28] of Si patterned structures. The proximal Si 3 N 4 layer is one of the key enablers for the formation of Ge spherical QDs and responsible for a unique phenomenon, namely, activating Ge-QD migration in the solid state within the already-formed SiO 2 layers during the thermal-oxidation process.…”

Section: Formation Of Self-organized Ge-qd/sio / Sige Sheets Within S...mentioning

confidence: 99%

“…EELS mapping, Energy-Dispersive linescans, and spectral analysis (Fig. 4) showed that the densification of Si 3 N 4 is achieved by an increase in both Si and N concentrations with essentially no change in the stoichiometric ratios [35] as well as being accompanied by phase transition from the amorphous to the nanocrystalline state [27,28,35]. The latter phase transition effect was evidenced by the appearance of spotty diffraction rings within nanobeam diffraction (NBD) patterns and diffraction peaks corresponding to α-or β-phase states in X-ray diffraction (XRD) spectra [27,28].…”

Section: Ge-qd-mediated Si 3 N 4 Densificationmentioning

confidence: 99%

“…4) showed that the densification of Si 3 N 4 is achieved by an increase in both Si and N concentrations with essentially no change in the stoichiometric ratios [35] as well as being accompanied by phase transition from the amorphous to the nanocrystalline state [27,28,35]. The latter phase transition effect was evidenced by the appearance of spotty diffraction rings within nanobeam diffraction (NBD) patterns and diffraction peaks corresponding to α-or β-phase states in X-ray diffraction (XRD) spectra [27,28]. Densified Si 3 N 4 is desired for the fabrication of Si 3 N 4 waveguides and related photonic devices due to the significant reduction in H-induced traps and the consequent reductions in absorption/propagation losses.…”

Section: Ge-qd-mediated Si 3 N 4 Densificationmentioning

confidence: 99%

“…The key engineering advantages of our combined, lithographically patterned as well as self-organized Ge-QD/ SiO 2 approaches lie in controllably positioning size-tunable spherical Ge-QDs at desired locations [27,28,39]. In so doing, we have created a large parameter space for designing advanced photonic devices exploiting quantum electrodynamics effects.…”

Section: Engineering Advantages Of Ge-qd/siomentioning

confidence: 99%

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The amazing world of self-organized Ge quantum dots for Si photonics on SiN platforms

et al. 2023

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Beginning with our exciting discovery of germanium (Ge) spherical quantum-dot (QD) formation via the peculiar and symbiotic interactions of Si, Ge, and O interstitials, we have embarked on a journey of vigorous exploration, creating unique configurations of self-organized Ge-QDs/Si-containing layers. Our aim is to generate advanced Ge-QD photonic devices, while using standard, mainstream Si processing techniques. This paper summarizes our portfolio of innovative Ge-QD configurations. With emphasis on both controllability and repeatability, we have fabricated size-tunable, spherical Ge-QDs that are placed at predetermined spatial locations within Si-containing layers (SiO2, Si3N4, and Si) using a coordinated combination of lithographic patterning and self-assembled growth. We have successfully exploited the multi-dimensional, parameter spaces of process conditions in combination with layout designs to achieve exquisite control available through the thermal oxidation of lithographically patterned, poly-Si1 − xGex structures in close proximity with Si3N4/Si layers. In so doing, we have gained insight into the growth kinetics and formation mechanisms of self-organized, Ge spherical QDs embedded within SiO2, Si3N4, and Si layers, respectively. Our Ge-QD configurations have opened up a myriad of process/integration possibilities including top-to-bottom evanescent-wave coupling structures for SiN-waveguided Ge-QD photodetectors and Ge-QD light emitters for Si photonics within Si3N4 integrated photonics platforms for on-chip interconnects and sensing.

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Section: And Si During Thermal-oxidation Processmentioning

confidence: 94%

Section: Formation Of Self-organized Ge-qd/sio / Sige Sheets Within S...mentioning

confidence: 99%

Section: Ge-qd-mediated Si 3 N 4 Densificationmentioning

confidence: 99%

Section: Ge-qd-mediated Si 3 N 4 Densificationmentioning

confidence: 99%

Section: Engineering Advantages Of Ge-qd/siomentioning

confidence: 99%

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The amazing world of self-organized Ge quantum dots for Si photonics on SiN platforms

et al. 2023

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Determination of exciton binding energy using photocurrent spectroscopy of Ge quantum-dot single-hole transistors under CW pumping

Hong,

Lai,

Tsai

et al. 2023

Sci Rep

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We reported exciton binding-energy determination using tunneling-current spectroscopy of Germanium (Ge) quantum dot (QD) single-hole transistors (SHTs) operating in the few-hole regime, under 405–1550 nm wavelength (λ) illumination. When the photon energy is smaller than the bandgap energy (1.46 eV) of a 20 nm Ge QD (for instance, λ = 1310 nm and 1550 nm illuminations), there is no change in the peak voltages of tunneling current spectroscopy even when the irradiation power density reaches as high as 10 µW/µm2. In contrast, a considerable shift in the first hole-tunneling current peak towards positive VG is induced (ΔVG ≈ 0.08 V at 0.33 nW/µm2 and 0.15 V at 1.4 nW/µm2) and even additional photocurrent peaks are created at higher positive VG values (ΔVG ≈ 0.2 V at 10 nW/µm2 irradiation) by illumination at λ = 850 nm (where the photon energy matches the bandgap energy of the 20 nm Ge QD). These experimental observations were further strengthened when Ge-QD SHTs were illuminated by λ = 405 nm lasers at much lower optical-power conditions. The newly-photogenerated current peaks are attributed to the contribution of exciton, biexciton, and positive trion complexes. Furthermore, the exciton binding energy can be determined by analyzing the tunneling current spectra.

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Self-Organized Germanium Quantum Dots/Si₃N₄ Enabling Monolithic Integration of Top Si₃N₄-Waveguided Microdisk Light Emitters and p-i-n Photodetectors for On-Chip Sensing

Lin

Hong

Lee

et al. 2023

IEEE Trans. Electron Devices

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Using a coordinated combination of lithographic patterning and self-assembled growth, Ge spherical quantum dots (QDs) were controllably generated within host layers of Si 3 N 4 as active medium for Si photonics. A significant fabrication advantage of our approach is the high-temperature thermal stability of Ge QDs that are formed by thermal oxidation of poly-SiGe lithographically patterned structures at 800 • C-900 • C, offering flexibility in the waveguide (WG)-material choices, co-design, and integration of Ge photonic devices. Our Ge QDs enable monolithic integration of microdisk light emitters and p-i-n photodetectors (PDs) with top-Si 3 N 4 WG-coupled structures using standard Si processing. Low dark current of 0.3 mA/cm 2 at 300 K and 0.2 µA/cm 2 at 77 K in combination with 3-dB frequency of 12 GHz for Ge-QD PDs and low threshold power of 0.6 kW/cm 2 for optically pumped Ge QD/SiN microdisks light emission evidence the high degree of crystallinity of our Ge QDs being an effective building block for 3-D SiN photonic integrated circuits. Index Terms-Ge, microdisks, photodiodes (PDs), quantum dot (QD), top-Si 3 N 4 waveguides (WGs).

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The Wonderful World of Designer Ge Quantum Dots

Cited by 4 publications

References 4 publications

The amazing world of self-organized Ge quantum dots for Si photonics on SiN platforms

The amazing world of self-organized Ge quantum dots for Si photonics on SiN platforms

Determination of exciton binding energy using photocurrent spectroscopy of Ge quantum-dot single-hole transistors under CW pumping

Self-Organized Germanium Quantum Dots/Si₃N₄ Enabling Monolithic Integration of Top Si₃N₄-Waveguided Microdisk Light Emitters and p-i-n Photodetectors for On-Chip Sensing

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The Wonderful World of Designer Ge Quantum Dots

Cited by 4 publications

References 4 publications

The amazing world of self-organized Ge quantum dots for Si photonics on SiN platforms

The amazing world of self-organized Ge quantum dots for Si photonics on SiN platforms

Determination of exciton binding energy using photocurrent spectroscopy of Ge quantum-dot single-hole transistors under CW pumping

Self-Organized Germanium Quantum Dots/Si3N4 Enabling Monolithic Integration of Top Si3N4-Waveguided Microdisk Light Emitters and p-i-n Photodetectors for On-Chip Sensing

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About

Self-Organized Germanium Quantum Dots/Si₃N₄ Enabling Monolithic Integration of Top Si₃N₄-Waveguided Microdisk Light Emitters and p-i-n Photodetectors for On-Chip Sensing