Ge nanocrystals in alumina matrix: A structural study

Kashtiban, Reza J.; Pinto, S. R. C.; Bangert, U.; Rolo, Anabela G.; Chahboun, A.; Gomes, M. J. M.; Harvey, A. J.

doi:10.1088/1742-6596/209/1/012060

Cited by 5 publications

(3 citation statements)

References 14 publications

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“…This peak is attributed to the optical phonon contribution of the Ge-Ge stretching mode [5] and is red-shifted by ≈ 8 cm −1 as compared to that of the bulk Ge (300 cm −1 ) [8], which is in agreement with the phonon confinement theory pre- diction for nanocrystals [9] whereby as the average size decreases the Raman peak broadens and shifts slightly to lower frequencies. Another sharp peak at 405.2 cm…”

Section: Resultssupporting

confidence: 85%

Structural and Optical Characterizations of Ge Nanostructures Fabricated by RF Magnetron Sputtering and Rapid Thermal Processing

et al. 2012

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In this work, we use a simple and cost effective technique of sputtering followed by the rapid thermal processing at 900• C for 30 s to form Ge nanostructures on the Si(100) substrate. A layer of Ge (300 nm) and Si cap layer (100 nm) were deposited using RF magnetron sputtering. Two samples were prepared: Ge layer with Si capping (Si/Ge/Si) and Ge layer without Si capping (Ge/Si). Scanning electron microscopy shows that subsequent annealing in a rapid thermal processing gives uniformed Ge or SiGe islands with an estimated size of 100-500 nm. For the Ge/Si sample, under post growth annealing there had vanished the deposited Ge layer as confirmed by energy dispersive X-ray analysis. Atomic force microscopy shows that the surface roughness increases by a factor of 15.55% as the islands formed. The Raman spectrum shows that good crystalline structures of the Ge and SiGe peaks are produced. High resolution X-ray diffraction reveals cubic and tetragonal Ge phases with estimated average crystallite sizes of 42 nm and 20 nm, respectively. The results showed that it is possible to grow high quality Ge and SiGe nanostructures using a simple technique of sputtering for potential applications in photonics and high speed devices.

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Section: Resultssupporting

confidence: 85%

Structural and Optical Characterizations of Ge Nanostructures Fabricated by RF Magnetron Sputtering and Rapid Thermal Processing

et al. 2012

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“…The crystallite sizes estimated from the Raman spectra were also included for comparison. The discrepancy of the XRD and the Raman spectra probably raised from the nanocrystal shape differences, of which in Raman fitting, a spherical shape was assumed, while in the XRD, the shape may be elongated, thereby giving the appearance of larger crystalline values (Kashtiban et al, 2010;Pinto et al, 2010). Another reason probably because of the Raman provided the average measurement from all crystallographic orientations, while the measurement by XRD was carried out only from the preferred orientations which were ( 111) and (400) reflections.…”

Section: High Resolution X-ray Diffraction Analysismentioning

confidence: 99%

Crystal orientation dependence of alternating current photo-assisted (ACPEC) porous silicon for potential optoelectronic application

Rahim

Mustakim

Razali

et al. 2019

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Purpose Porous silicon (PS) was successfully fabricated using an alternating current photo-assisted electrochemical etching (ACPEC) technique. This study aims to compare the effect of different crystal orientation of Si n(100) and n(111) on the structural and optical characteristics of the PS. Design/methodology/approach PS was fabricated using ACPEC etching with a current density of J = 10 mA/cm2 and etching time of 30 min. The PS samples denoted by PS100 and PS111 were etched using HF-based solution under the illumination of an incandescent white light. Findings FESEM images showed that the porous structure of PS100 was a uniform circular shape with higher density and porosity than PS111. In addition, the AFM indicated that the surface roughness of porous n(100) was less than porous n(111). Raman spectra of the PS samples showed a stronger peak with FWHM of 4.211 cm−1 and redshift of 1.093 cm−1. High resolution X-ray diffraction revealed cubic Si phases in the PS samples with tensile strain for porous n(100) and compressive strain for porous n(111). Photoluminescence observation of porous n(100) and porous n(111) displayed significant visible emissions at 651.97 nm (Eg = 190eV) and 640.89 nm (Eg = 1.93 eV) which was because of the nano-structure size of silicon through the quantum confinement effect. The size of Si nanostructures was approximately 8 nm from a quantized state effective mass theory. Originality/value The work presented crystal orientation dependence of Si n(100) and n(111) for the formation of uniform and denser PS using new ACPEC technique for potential visible optoelectronic application. The ACPEC technique has effectively formed good structural and optical characteristics of PS.

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“…All the detectable peaks could be indexed as the Ge diamond structure found in the standard reference data (JCPDS 4-0545). [8] It is clearly seen that the reflection peaks become sharper with increasing the annealing temperature, indicating the enhancement of crystallinity. As a result of annealing, the corresponding FWHM of the peaks decreases and the particle size increases as authenticated by Scherer (Fig.…”

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confidence: 94%

Efficient Visible Photoluminescence from Self-Assembled Ge QDs Embedded in Silica Matrix

Samavati

Ismail³

et al. 2017

Chinese Phys. Lett.

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Measuring the growth parameters of Ge quantum dots (QDs) embedded in SiO2/Si hetero-structure is pre-requisite for developing the optoelectronic devices such as photovoltaics and sensors. Their optical properties can be tuned by tailoring the growth morphology and structures, where the growth parameters' optimizations still need to be explored. We determine the effect of annealing temperature on surface morphology, structures and optical properties of Ge/SiO2/Si hetero-structure. Samples are grown via rf magnetron sputtering and subsequent characterizations are made using imaging and spectroscopic techniques.

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Ge nanocrystals in alumina matrix: A structural study

Cited by 5 publications

References 14 publications

Structural and Optical Characterizations of Ge Nanostructures Fabricated by RF Magnetron Sputtering and Rapid Thermal Processing

Structural and Optical Characterizations of Ge Nanostructures Fabricated by RF Magnetron Sputtering and Rapid Thermal Processing

Crystal orientation dependence of alternating current photo-assisted (ACPEC) porous silicon for potential optoelectronic application

Efficient Visible Photoluminescence from Self-Assembled Ge QDs Embedded in Silica Matrix

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