Ge quantum dot lattices in alumina prepared by nitrogen assisted deposition: Structure and photoelectric conversion efficiency

Tkalčević, Marija; Basioli, Lovro; Salamon, Krešimir; Šarić, Iva; Sancho‐Parramon, Jordi; Bubaš, Matej; Bogdanović-Radović, Ivančica; Bernstorff, Sigrid; Fogarassy, Zsolt; Balázsi, Katalin; Petravić, M.; Mičetić, Maja

doi:10.1016/j.solmat.2020.110722

Cited by 11 publications

(14 citation statements)

References 34 publications

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“…There is considerable interest in nanostructured materials from the group IV Si-Ge system for photonics applications [1][2][3][4][5][6][7][8][9][10]. However, the most important inconvenience of this system is the low light absorption-emission efficiency of bulk Si-Ge with an indirect band gap that counts against the long-held goal of integrated group IV photonics.…”

Section: Introductionmentioning

confidence: 99%

Nanocrystallized Ge-Rich SiGe-HfO2 Highly Photosensitive in Short-Wave Infrared

et al. 2021

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Group IV nanocrystals (NCs), in particular from the Si–Ge system, are of high interest for Si photonics applications. Ge-rich SiGe NCs embedded in nanocrystallized HfO2 were obtained by magnetron sputtering deposition followed by rapid thermal annealing at 600 °C for nanostructuring. The complex characterization of morphology and crystalline structure by X-ray diffraction, μ-Raman spectroscopy, and cross-section transmission electron microscopy evidenced the formation of Ge-rich SiGe NCs (3–7 nm diameter) in a matrix of nanocrystallized HfO2. For avoiding the fast diffusion of Ge, the layer containing SiGe NCs was cladded by very thin top and bottom pure HfO2 layers. Nanocrystallized HfO2 with tetragonal/orthorhombic structure was revealed beside the monoclinic phase in both buffer HfO2 and SiGe NCs–HfO2 layers. In the top part, the film is mainly crystallized in the monoclinic phase. High efficiency of the photocurrent was obtained in a broad spectral range of curves of 600–2000 nm at low temperatures. The high-quality SiGe NC/HfO2 matrix interface together with the strain induced in SiGe NCs by nanocrystallization of both HfO2 matrix and SiGe nanoparticles explain the unexpectedly extended photoelectric sensitivity in short-wave infrared up to about 2000 nm that is more than the sensitivity limit for Ge, in spite of the increase of bandgap by well-known quantum confinement effect in SiGe NCs.

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Section: Introductionmentioning

confidence: 99%

Nanocrystallized Ge-Rich SiGe-HfO2 Highly Photosensitive in Short-Wave Infrared

et al. 2021

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“…We argue that a lattice of non-ordered Ge QDs is formed after annealing. In comparison, the annealing of Ge QDs in a high vacuum (700 °C, 45 min) did not change their shape properties [ 19 ].…”

Section: Resultsmentioning

confidence: 99%

“…Our previous work demonstrates weak MEG in Ge QDs in alumina matrix, prepared in nitrogen-rich working gas during magnetron sputtering deposition [ 19 ]. The present paper investigates the photoelectric conversion properties and MEG probability in Ge QWs embedded in the amorphous alumina matrix.…”

Section: Introductionmentioning

confidence: 99%

Multiple Exciton Generation in 3D-Ordered Networks of Ge Quantum Wires in Alumina Matrix

et al. 2022

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Thin films containing 3D-ordered semiconductor quantum wires offer a great tool to improve the properties of photosensitive devices. In the present work, we investigate the photo-generated current in thin films consisting of an interconnected 3D-ordered network of Ge quantum wires in an alumina matrix. The films are prepared using nitrogen-assisted magnetron sputtering co-deposition of Ge and Al2O3. We demonstrate a strong photocurrent generation in the films, much stronger than in similar films containing Ge quantum dots. The enhanced photocurrent generation is the consequence of the multiple exciton generation and the films’ specific structure that allows for efficient carrier transport. Thin film with the largest nitrogen content showed enhanced performance compared to other thin films with 1.6 excitons created after absorption of a single photon at an energy nearly equal to the double bandgap value. The bandgap value depends on the geometrical properties of the quantum wires, and it is close to the maximum of the solar irradiance in this case. In addition, we show that the multiple exciton generation is the most pronounced at the photon energy values equal to multiple values of the thin film bandgap.

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“…Special focus is also given to the research of Ge quantum dots (QD)/nanocrystals (NCs) for photodetectors [22][23][24][25][26], solar energy harvesting [27,28] and conversion devices [29] or for light emission and integrated light sources [30][31][32], and also for floating gate non-volatile memory devices [33][34][35]. Ge NCs are compatible with mainstream CMOS technology and present reduced thermal budget compared to Si NCs formation, and also larger exciton Bohr radius than Si.…”

Section: Introductionmentioning

confidence: 99%

FROM Si NANOWIRES TO Ge NANOCRYSTALS FOR VIS-NIR-SWIR SENSORS AND NON-VOLATILE MEMORIES: A REVIEW

Lepadatu¹,

Stavarache²,

Palade³

et al. 2022

AnnalsARSciPhysChem

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"Nanocrystalline Si and Ge are ofhigh interestfor integrated Si photonics related to light emission, opticul sensors, photodetectors, solar energy harvesting and conversion devices, and also forfloating gate non-volatile memories (NVMs). In this review, we have focused on nanocrystalline porous Si (nc-PS) with extension to Si nanodots, and Ge nanocrystals (NCs)Zquantum dots (QDs)/nanoparticles (NPs) embedded in oxides (SiCh, TiCE, HfCh, AI2O3). The great asset ofnc-PS is its intense photoluminescence in VIS at room temperature (RT), while Ge NCs/NPs embedded in oxides show high photosensitivity in VISNIR-SWIR in the spectral photocurrent up to 1325 nm at RT. Ge NCs/NPs/QDsfloating gate NVMs present high memory performance, the retention characteristics corresponding to the state of the art for NCs floating gate NVMs. We prove the relevance of controlling the preparation parametersfor obtainingfilms with targetedphotoluminescence, photosensitivity and charge storage properties for applications, e.g. VIS-NIR-SWIR optical sensors and photodetectors, and electronic and photoelectric NVMs. We evidence the correlation of preparation conditions, morphology, composition and crystalline structure with optical, electrical, photoelectrical and charge storage properties and also evidence the contribution ofquantum confinement effect, localized States and trapping centers."

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Ge quantum dot lattices in alumina prepared by nitrogen assisted deposition: Structure and photoelectric conversion efficiency

Cited by 11 publications

References 34 publications

Nanocrystallized Ge-Rich SiGe-HfO2 Highly Photosensitive in Short-Wave Infrared

Nanocrystallized Ge-Rich SiGe-HfO2 Highly Photosensitive in Short-Wave Infrared

Multiple Exciton Generation in 3D-Ordered Networks of Ge Quantum Wires in Alumina Matrix

FROM Si NANOWIRES TO Ge NANOCRYSTALS FOR VIS-NIR-SWIR SENSORS AND NON-VOLATILE MEMORIES: A REVIEW

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