Crystallization of Amorphous Germanium Films and Multilayer a-Ge/a-Si Structures upon Exposure to Nanosecond Laser Radiation

Володин, В. А.; Krivyakin, G. K.; Ивлев, Г. Д.; Prokopyev, S. L.; Гусакова, С. В.; Попов, А. А.

doi:10.1134/s1063782619030217

Cited by 25 publications

(16 citation statements)

References 27 publications

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“…Figure c shows that all Ge peaks obtained from the current poly-Ge layers shift to wavenumbers lower than 300 cm –1 , which is the value for an sc-Ge wafer. Although phonon confinement in nanocrystalline Ge could be the cause of peak shifts, , no nanocrystals were found in the upper Ge region evaluated by the Raman spectroscopy, as described later. Therefore, the peak shift likely originated from the tensile strain in Ge mainly caused by thermal expansion difference between Ge and the substrate .…”

Section: Results and Discussionmentioning

confidence: 90%

Record-High Hole Mobility Germanium on Flexible Plastic with Controlled Interfacial Reaction

Imajo

Ishiyama

Saitoh³

et al. 2021

ACS Appl. Electron. Mater.

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A semiconductor thin film with high carrier mobility was fabricated on a flexible film. During the solid-phase crystallization process of the densified amorphous Ge layer, the interfacial reaction with the GeO x underlayer is controlled by the GeO x thickness (0–300 nm) and the growth temperature (375–450 °C). The appropriate amount of oxygen diffusion from GeO x to Ge produces large Ge grains (up to 13 μm in diameter) with high crystal quality. The use of a high heat-resistant polyimide film allows postannealing at 500 °C and improves the hole mobility of Ge to 690 cm2 V–1 s–1 while maintaining flexibility. This hole mobility is higher than that of any other semiconductor thin films directly formed on insulators, including single-crystal Ge grown at high temperatures, and even higher than that of a Si wafer. The findings open up the possibility of incorporating high-speed transistors on flexible devices that surpass Si metal–oxide–semiconductor field-effect transistors.

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Section: Results and Discussionmentioning

confidence: 90%

Record-High Hole Mobility Germanium on Flexible Plastic with Controlled Interfacial Reaction

Imajo

Ishiyama

Saitoh³

et al. 2021

ACS Appl. Electron. Mater.

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“…The crystallites with dimensions greater than 100 nm can consist of slightly misoriented nanocrystals. These crystallites can contain structural defects and may experience stretching strains. , The crystal quality is preserved throughout the 300 nm thick film, even on the glass substrate. We explain the dynamics of single-pulse LC of a-Ge to be EC and that of high-overlap pulse scan LC to be of a slow-quenching crystallization nature based on the crystal domain orientation and their elongated fan-like radial lateral organization, as well as in light of our previous studies. , Successful crystallization of a-Ge thin film is confirmed by optical microscopy, Raman spectroscopy, SEM, EBSD, and XRD measurements.…”

Section: Discussionmentioning

confidence: 99%

“…These crystallites can contain structural defects and may experience stretching strains. 45,46 The crystal quality is preserved throughout the 300 nm thick film, even on the glass substrate. We explain the dynamics of single-pulse LC of a-Ge to be EC and that of highoverlap pulse scan LC to be of a slow-quenching crystallization nature based on the crystal domain orientation and their elongated fan-like radial lateral organization, as well as in light of our previous studies.…”

Section: ■ Conclusionmentioning

confidence: 99%

Laser Crystallization of Amorphous Ge Thin Films via a Nanosecond Pulsed Infrared Laser

Korkut

Çınar

Kabaçelik

et al. 2021

Crystal Growth & Design

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Understanding the dynamics of the laser crystallization (LC) process of Ge thin films by nanosecond (ns) pulsed infrared (IR) lasers is important for producing homogeneous, crack-free crystalline device-grade films for use in thin-film transistors, photo-detectors, particle detectors, and photovoltaic applications. Our motivation is to describe a ns IR laser-based crystallization process of Ge by implementing suitable parameters to fabricate thin-film devices. Our LC technique was applied to crystallize thin amorphous Ge (a-Ge) films with thicknesses suitable for device applications. The LC process was applied to a 300 nm-thick a-Ge thin film utilizing a 200 ns pulsed IR laser with a wavelength of 1064 nm. Electron-beam-evaporation-deposited a-Ge on glass substrates were subject to successive ns laser pulses with a line focus. The crystallinity of the polycrystalline Ge (pc-Ge) films was evaluated by Raman spectroscopy, optical microscopy, and electron backscatter diffraction (EBSD). LC-Ge exhibited a Raman peak of around 300 cm–1, confirming successful crystallization of a-Ge. pc-Ge domain sizes exceeding several tens of micrometers were observed in EBSD scans. LC of a-Ge minimizes the thermal energy budget of processing and provides flexibility to locally crystallize the film. Our work is the first demonstration of the LC of a-Ge thin films, resulting in domain sizes exceeding tens of micrometers via a ns pulsed IR laser.

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“…The introduction of germanium and tin nanoparticles into an undoped layer of p-i-n structures based on amorphous and microcrystalline silicon films increased the efficiency of solar cells [6][7][8][9] and expanded the absorption spectrum toward longer wavelengths in solar cells and photodiodes [10]. Creation of these structures on large-size non-refractory substrates is possible using plasmaenhanced chemical vapor deposition (PECVD) technology followed by pulsed laser annealing [11].…”

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confidence: 99%

“…A multilayer heteronanostructure comprising three pairs of amorphous silicon and amorphous germanium (a-Ge/a-Si:H) layers (15/40 nm thick, respectively) was grown by the low-frequency (55 kHz) PECVD method at 225°C on (001)-oriented silicon substrate. Germanium and silicon layers were sequentially grown by decomposition of germane (GeH 4 ) and silane (SiH 4 ), respectively, so that the first and last layers consisted of a-Si:H. The growth conditions were described in more detail elsewhere [11].…”

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confidence: 99%

Vertical Ordering of Amorphous Ge Nanoclusters in Multilayer a-Ge/a-Si:H Heterostructures

2021

Self Cite

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We have studied a multilayer heteronanostructure comprising three pairs of amorphous silicon and amorphous germanium (a-Ge/a-Si:H) layers grown at 225°C on a silicon substrate by the method of lowfrequency plasma-enhanced chemical vapor deposition. The phase composition of silicon and germanium layers was determined by Raman spectroscopy, which showed that the layers are completely amorphous. Transmission electron microscopy images revealed the presence of amorphous Ge nanoclusters ordered in the vertical direction, the formation of which was initiated by local nanometer-scale inhomogeneities in the first Ge layer, the lateral dimensions of which grow on the passage from bottom to top layer.

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Crystallization of Amorphous Germanium Films and Multilayer a-Ge/a-Si Structures upon Exposure to Nanosecond Laser Radiation

Cited by 25 publications

References 27 publications

Record-High Hole Mobility Germanium on Flexible Plastic with Controlled Interfacial Reaction

Record-High Hole Mobility Germanium on Flexible Plastic with Controlled Interfacial Reaction

Laser Crystallization of Amorphous Ge Thin Films via a Nanosecond Pulsed Infrared Laser

Vertical Ordering of Amorphous Ge Nanoclusters in Multilayer a-Ge/a-Si:H Heterostructures

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