High Hole Mobility of Polycrystalline GeSn Layers Grown by Hot‐Wire Chemical Vapor Deposition on Diamond Substrates

Buzynin, Yury N.; Шенгуров, В. Г.; Денисов, С. А.; Yunin, P. A.; Chalkov, V. Yu.; Дроздов, М. Н.; Korolyov, Sergei A.; Нежданов, А. В.

doi:10.1002/pssr.202100421

Cited by 6 publications

(3 citation statements)

References 21 publications

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“…Techniques for synthesizing thin films of high-mobility materials on insulating substrates have been extensively studied. Ge has been a preferred TFT channel material owing to its high carrier mobility and relatively low crystallization temperature. , The performance of metal-oxide semiconductor field-effect transistors (MOSFETs) based on single-crystal Ge (sc-Ge) has surpassed that of Si MOSFETs because of the gate stack technologies − and thin-film structure. − To date, polycrystalline Ge (poly-Ge) thin films have been synthesized at low temperatures using various techniques, such as solid-phase crystallization (SPC), − laser annealing, − chemical vapor deposition, − lamp annealing, − plasma irradiation, seed layer technique, and metal-induced crystallization. − However, owing to the poor quality of poly-Ge, particularly in thin films (<100 nm), which are required for reducing the off-current of TFTs, the practical use of poly-Ge-based TFTs on glass has yet to be achieved.…”

Section: Introductionmentioning

confidence: 99%

Interfacial Nucleation Control in Amorphous GeSn Thin Films Using Bilayer Structure

Maeda

Ishiyama

Saitoh³

et al. 2023

Crystal Growth & Design

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Remarkable progress has been made in germanium-based thin-film transistors in recent years. However, achieving both high field-effect mobility and a high on–off ratio is difficult because the crystallinity of polycrystalline Ge degrades as it becomes thinner. In this study, we investigated the interfacial nucleation control and grain size enlargement in the solid-phase crystallization of amorphous Ge thin films (≤50 nm). A bilayer structure consisting of top nucleation and bottom nucleation suppression layers promoted nucleation at the surface rather than at the substrate interface, resulting in a significant enlargement of the grain size. In addition, Sn doping in Ge increased the grain size to 12 μm, which was larger than that of most polycrystalline Ge thin films and contributed to the reduction in acceptor defects and improvement in hole mobility. The resulting hole mobility (260 cm2 V–1 s–1) and hole concentration (3 × 1017 cm–3) in the GeSn layer were among the highest for polycrystalline Ge-based thin films. These results will contribute to the realization of low-temperature Ge-based thin-film transistors that could be superior to single-crystal Si transistors, leading to innovations in display devices.

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Section: Introductionmentioning

confidence: 99%

Interfacial Nucleation Control in Amorphous GeSn Thin Films Using Bilayer Structure

Maeda

Ishiyama

Saitoh³

et al. 2023

Crystal Growth & Design

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“…Ge 1−x Sn x alloys have attracted considerable attention in Si-based optoelectronic device integration because of their enhanced carrier mobility, adjustable band gap structure and compatibility with the CMOS processes [1][2][3][4][5]. Efficient devices based on Ge 1−x Sn x have been fabricated, including thin film transistors [6][7][8][9], solar cells [10], photodetectors [11][12][13], LEDs [14][15][16][17], lasers [18,19], etc.…”

Section: Introductionmentioning

confidence: 99%

Effect of Growth Temperature on Crystallization of Ge1−xSnx Films by Magnetron Sputtering

Huang

Zhao

et al. 2022

Crystals

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Ge1−xSnx film with Sn content (at%) as high as 13% was grown on Si (100) substrate with Ge buffer layer by magnetron sputtering epitaxy. According to the analysis of HRXRD and Raman spectrum, the quality of the Ge1−xSnx crystal was strongly dependent on the growth temperature. Among them, the GeSn (400) diffraction peak of the Ge1−xSnx film grown at 240 °C was the lowest, which is consistent with the Raman result. According to the transmission electron microscope image, some dislocations appeared at the interface between the Ge buffer layer and the Si substrate due to the large lattice mismatch, but a highly ordered atomic arrangement was observed at the interface between the Ge buffer layer and the Ge1−xSnx layer. The Ge1−xSnx film prepared by magnetron sputtering is expected to be a cost-effective fabrication method for Si-based infrared devices.

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“…[36,37] The crystallization temperature was lowered, [38,39] grain size was enlarged, [40,41] p was reduced, [42] energy barrier height of the grain boundary was lowered, [43] and then hole mobility μ was enhanced. [39][40][41][42][43][44][45] However, p of the order of 10 16 cm À3 has never been achieved, which is essential for extensive Fermi level control using impurity doping. In this study, to reduce the defect-induced acceptors in poly-Ge, we investigated a combination of Sn addition and GeO 2 underlayer insertion in the SPC of the densified a-Ge layer.…”

Section: Introductionmentioning

confidence: 99%

Solid‐Phase Crystallization of GeSn Thin Films on GeO₂‐Coated Glass

Mizoguchi

Ishiyama

Moto

et al. 2021

Physica Rapid Research Ltrs

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Polycrystalline Ge thin films are promising candidates for next‐generation thin‐film transistors. However, the difficulty in Fermi‐level control due to the high density of defect‐induced acceptors has been one of the main problems for device applications. Herein, GeO2 preparation and Sn addition are combined in the advanced low‐temperature (375 °C) solid‐phase crystallization of Ge layers that have been recently developed. The GeO2 underlayer works effectively at a low Sn composition (< 4%), enlarging the grain size by a magnification of ≈5. An appropriate amount of unsubstituted Sn reduces acceptor defects and achieves a minimum hole concentration of 3 × 1016 cm−3 by combining post‐annealing (500 °C). This hole concentration is the lowest level for undoped polycrystalline Ge‐based thin films, which allows control over their Fermi level widely by impurity doping. Although the lower hole concentration provides a higher energy barrier height of the grain boundary, the hole mobility is maintained at 190 cm2 V−1 s−1 owing to the large grains (15 μm diameter). This achievement paves the way for the implementation of poly‐Ge‐based thin films in various semiconductor devices, including advanced thin‐film transistors.

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High Hole Mobility of Polycrystalline GeSn Layers Grown by Hot‐Wire Chemical Vapor Deposition on Diamond Substrates

Cited by 6 publications

References 21 publications

Interfacial Nucleation Control in Amorphous GeSn Thin Films Using Bilayer Structure

Interfacial Nucleation Control in Amorphous GeSn Thin Films Using Bilayer Structure

Effect of Growth Temperature on Crystallization of Ge1−xSnx Films by Magnetron Sputtering

Solid‐Phase Crystallization of GeSn Thin Films on GeO₂‐Coated Glass

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High Hole Mobility of Polycrystalline GeSn Layers Grown by Hot‐Wire Chemical Vapor Deposition on Diamond Substrates

Cited by 6 publications

References 21 publications

Interfacial Nucleation Control in Amorphous GeSn Thin Films Using Bilayer Structure

Interfacial Nucleation Control in Amorphous GeSn Thin Films Using Bilayer Structure

Effect of Growth Temperature on Crystallization of Ge1−xSnx Films by Magnetron Sputtering

Solid‐Phase Crystallization of GeSn Thin Films on GeO2‐Coated Glass

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Solid‐Phase Crystallization of GeSn Thin Films on GeO₂‐Coated Glass