Single phase Si<sub>1−<i>x</i></sub>Gex nanocrystals and the shifting of the E1 direct energy transition

Ha, Nam Chul; Giang, Nguyen Truong; Thuy, Truong Thi; Trung, Nguyễn Ngọc; Dung, Nguyen Duc; Saeed, Saba; Gregorkiewicz, T.

doi:10.1088/0957-4484/26/37/375701

Cited by 12 publications

(10 citation statements)

References 34 publications

(37 reference statements)

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“…The possibility of carrier captured at defect levels within the core of the NCs seems also unlikely when we consider the influence of the NC size on the E thres . The nanocrystal sizes ranging from 5 nm to 14 nm, and particle density of n ≈ 2 × 10 –17 cm –3 , were established in our previous studies . With the Gaussian fit, we obtain the size distribution of Si–Ge alloy NCs with the mean value of 9 nm and standard deviation of 3 nm (data not shown).…”

Section: Resultsmentioning

confidence: 86%

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Spectral probing of carrier traps in Si–Ge alloy nanocrystals

Giang

Khiem

et al. 2016

Physica Rapid Research Ltrs

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Photogenerated carriers in Si–Ge alloy nanocrystals (NCs) prepared by co‐sputtering method were investigated by mean of transient induced absorption. The carrier relaxation features multiple components, with three decay life times of τ ≈ 600 fs, 12 ps, and 15 ns, established for Si0.2Ge0.8 alloy NCs of a mean crystal size of 9 nm and standard deviation of 3 nm. Deep carrier traps, identified at the boundary between the NCs and the SiO2 host with the ionization energy of about 1 eV, are characterized by a long‐range Coulombic potential. These are responsible for rapid depletion of free carrier population within a few picoseconds after the excitation, which explains the low emissivity of the investigated materials, and also sheds light on the generally low luminescence of Si/Ge and Ge NCs. (© 2016 WILEY‐VCH Verlag GmbH &Co. KGaA, Weinheim)

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Section: Resultsmentioning

confidence: 86%

“…The single‐phase Si 1– x Ge x ( x = 0.2, 0.4, 0.6, 0.8) alloy NCs have been formed in the SiO 2 host matrix upon heat treatment. Detailed sample preparation and characterization can be found elsewhere .…”

Section: Resultsmentioning

confidence: 99%

Spectral probing of carrier traps in Si–Ge alloy nanocrystals

Giang

Khiem

et al. 2016

Physica Rapid Research Ltrs

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“…The increasing research efforts to incorporate different semiconductor nanocrystals (NCs), in particular NCs containing group IV elements such as Si, Ge or SiGe NCs dielectric films continued along the last decades because of the possibility to tune electrical and optical properties by varying the NCs size, composition and density [1][2][3][4][5][6] . It was shown that the matrix material has influence on the Ge NCs size, density and shape, and passivation quality of Ge NC/matrix interface 4,7 .…”

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confidence: 99%

SiGe nanocrystals in SiO2 with high photosensitivity from visible to short-wave infrared

Stavarache

Logofatu

Sultan

et al. 2020

Sci Rep

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Films of SiGe nanocrystals (NCs) in oxide have the advantage of tuning the energy band gap by adjusting SiGe NCs composition and size. In this study, SiGe-SiO2 amorphous films were deposited by magnetron sputtering on Si substrate followed by rapid thermal annealing at 700, 800 and 1000 °C. We investigated films with Si:Ge:SiO2 compositions of 25:25:50 vol.% and 5:45:50 vol.%. TEM investigations reveal the major changes in films morphology (SiGe NCs with different sizes and densities) produced by Si:Ge ratio and annealing temperature. XPS also show that the film depth profile of SiGe content is dependent on the annealing temperature. These changes strongly influence electrical and photoconduction properties. Depending on annealing temperature and Si:Ge ratio, photocurrents can be 103 times higher than dark currents. The photocurrent cutoff wavelength obtained on samples with 25:25 vol% SiGe ratio decreases with annealing temperature increase from 1260 nm in SWIR for 700 °C annealed films to 1210 nm for those at 1000 °C. By increasing Ge content in SiGe (5:45 vol%) the cutoff wavelength significantly shifts to 1345 nm (800 °C annealing). By performing measurements at 100 K, the cutoff wavelength extends in SWIR to 1630 nm having high photoresponsivity of 9.35 AW−1.

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“…Subsequently, the as-grown samples were annealed at 800 °C in continuous-flow N2 gas for 30 min for crystallization. More details on the samples preparation and some characterizations can be also found elsewhere [8,9]. Two samples containing pure GeNCs and Si-Ge alloy NCs with the Si:Ge ratio of 3:2 entitled with GeT800 and Si4Ge6T800, respectively.…”

Section: Samplesmentioning

confidence: 99%

“…Two samples containing pure GeNCs and Si-Ge alloy NCs with the Si:Ge ratio of 3:2 entitled with GeT800 and Si4Ge6T800, respectively. The crystal sizes of all samples in the range from about 5-10 nm were estimated via X-ray diffraction patterns by using Debye-Sheerer equation and reported in the independent studies [8,10]. Figure 3 shows transient induced absorption of the photo-generated charge carriers in the sample Si4Ge6T800 recorded at the probe photon energy Eprobe = 1 eV (1240 nm).…”

Section: Samplesmentioning

confidence: 99%

Application of Pump-Probe Technique for Tracking of Charge Carrier Relaxation In Nanostructured Semiconductors

Ha¹

2021

MaP

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The pump-probe technique is a powerful tool for probing and characterizing the electronic and structural properties of short-lived excited states of materials. Upon the absorption of photons of the pump, excited states of the materials are established. Relaxation of these states reflects many physical aspects of the materials which can be tracked by a consequent beam – the probe. In this study, we present a conventional pump-probe technique at the University of Amsterdam and its application for tracking relaxation of charge carriers in thin films containing Si and Ge nanocrystals embedded in SiO2 matrix. The pump beam is obtained from a 150-fs laser pulse with the photon wavelength at 340 nm. The probe beam is constituted from a white-light beam in the wavelength range from approximately 900 - 1300 nm (0.9 - 1.4 eV). The photon-generated charge carriers feature with multi-exponent decay dynamics, involving to different physical characteristics. The fast decay components of about few ps time scale arise from defect-related trapping or Auger processes, while the slow decay components of about few hundred ps come from relaxation of the exciton left in the semiconductor nanocrystals. The deep-insight characterization of the materials involving to individual relaxation processes are presented and discussed.

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Single phase Si_1−xGex nanocrystals and the shifting of the E1 direct energy transition

Cited by 12 publications

References 34 publications

Spectral probing of carrier traps in Si–Ge alloy nanocrystals

Spectral probing of carrier traps in Si–Ge alloy nanocrystals

SiGe nanocrystals in SiO2 with high photosensitivity from visible to short-wave infrared

Application of Pump-Probe Technique for Tracking of Charge Carrier Relaxation In Nanostructured Semiconductors

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Single phase Si1−xGex nanocrystals and the shifting of the E1 direct energy transition

Cited by 12 publications

References 34 publications

Spectral probing of carrier traps in Si–Ge alloy nanocrystals

Spectral probing of carrier traps in Si–Ge alloy nanocrystals

SiGe nanocrystals in SiO2 with high photosensitivity from visible to short-wave infrared

Application of Pump-Probe Technique for Tracking of Charge Carrier Relaxation In Nanostructured Semiconductors

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Single phase Si_1−xGex nanocrystals and the shifting of the E1 direct energy transition