Observation of step-flow growth in femtosecond pulsed laser deposition of Si on Si(100)-2×1

Hegazy, M. S.; Elsayed-Ali, Hani E.

doi:10.1116/1.1517257

Cited by 12 publications

(5 citation statements)

References 18 publications

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“…Similar results were observed for the Si homoepitaxy at low temperatures. 32 For deposition at 400°C, the formation of elongated hut clusters was observed as shown in Fig. 8͑b͒.…”

Section: B Effect Of Laser Fluencementioning

confidence: 86%

“…The Si͑100͒ samples are first cleaned by chemical etching using a modification to the Shiraki method. 32 The samples are dipped into a solution of H 2 SO 4 ͑97 wt % ͒ :H 2 O 2 ͑30 wt % ͒ =4:1 ͑by volume͒ for 10 min, rinsed with ultrapure water for 10 min, then dipped into a solution of HF ͑50 wt % ͒ :H 2 O=1:10 ͑by volume͒ for 1 min. The samples are loaded into the vacuum chamber within 5 min of chemical cleaning.…”

Section: Methodsmentioning

confidence: 99%

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Growth of Ge quantum dots on Si(100)-(2×1) by pulsed laser deposition

Hegazy

Elsayed-Ali

2006

Journal of Applied Physics

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Self-assembled germanium quantum dots ͑QDs͒ were grown on Si͑100͒-͑2 ϫ 1͒ by pulsed laser deposition. In situ reflection-high energy electron diffraction ͑RHEED͒ and postdeposition atomic force microscopy are used to study the growth of the QDs. Several films of different thicknesses were grown at a substrate temperature of 400°C using a Q-switched Nd:yttrium aluminum garnet laser ͑ = 1064 nm, 40 ns pulse width, 23 J / cm 2 fluence, and 10 Hz repetition rate͒. At low film thicknesses, hut clusters that are faceted by different planes, depending on their height, are observed after the completion of the wetting layer. With increasing film thickness, the size of the clusters grows and they gradually lose their facetation and become more rounded. With further thickness increase, the shape of these clusters becomes domelike with some pyramids observed among the majority of domes. The effect of the laser fluence on the morphology of the grown clusters was studied. The cluster density was found to increase dramatically while the average cluster size decreased with the increase in the laser fluence. For a laser fluence of 70 J / cm 2 , dome-shaped clusters that are smaller than the large huts formed at 23 J / cm 2 were observed. At a substrate temperature of 150°C, misoriented three-dimensional ͑3D͒ clusters are formed producing only a RHEED background. At 400 and 500°C, huts and a lower density of domes are formed, respectively. Above 600°C, 3D clusters are formed on top of a discontinuous textured layer.

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“…Similar results were observed for the Si homoepitaxy at low temperatures. 32 For deposition at 400°C, the formation of elongated hut clusters was observed as shown in Fig. 8͑b͒.…”

Section: B Effect Of Laser Fluencementioning

confidence: 86%

Section: Methodsmentioning

confidence: 99%

Growth of Ge quantum dots on Si(100)-(2×1) by pulsed laser deposition

Hegazy

Elsayed-Ali

2006

Journal of Applied Physics

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“…1. Si substrates are chemically cleaned prior being loading into the vacuum chamber [9]. The chamber is pumped down to a pressure of <1×10 -8 Torr and baked for 12-24 hours before flashing the substrate to ~1100 ºC in order for the 2×1 reconstruction to develop.…”

Section: Photodetector Fabricationmentioning

confidence: 99%

Quantum-dot Infrared Photodetector Fabricated by Pulsed Laser Deposition Technique

Elsayed-Ali¹

2006

JLMN

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Pulsed laser deposition is used to fabricate multilayered Ge quantum-dot photodetector on Si(100). Growth was studied by reflection high-energy electron diffraction and atomic force microscopy. The difference in the current values in dark and illumination conditions was used to measure the device sensitivity to radiation. Spectral responsivity measurements reveal a peak around 2 μm, with responsity that increases three orders of magnitude as bias increases from 0.5 to 3.5 V.

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“…PLD produces energetic species, which results in the increase of the sticking coefficients and adatom surface mobility, enhancing epitaxy [2]. Epitaxial thin films of InP on GaAs(100) and Si on Si(100) were obtained using PLD [3,4]. Using femtosecond (fs) laser minimizes or eliminates particulates formation, which improves the grown thin film quality.…”

Section: Introductionmentioning

confidence: 99%

Femtosecond Pulsed Laser Deposition of Indium on Si(100)

Elsayed-Ali¹

2006

JLMN

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We have been studying the refractive index changes and vacancies that are induced in transparent materials like glass by the irradiation of femtosecond laser pulses. This technique has been applied to fabricate three-dimensional photonic structures such as optical data storages, waveguides, gratings, and couplers inside a wide variety of transparent materials. We report micro-fabrication experiments of optical elements in glasses with femtosecond laser pulses, including fabrication of couplers, Bragg gratings, and zone plates and holograms on the surface of glass. A trial fabrication experiment on organic materials is also reported.Keywords: femtosecond, laser pulse, fabrication, three-dimensional, optical elements INTRODUCTIONMicromachining by femtosecond laser pulses in transparent materials has recently received much attention. When femtosecond laser pulses are focused inside the bulk of a transparent material, the intensity in the focal volume can become high enough to cause nonlinear absorption, which leads to localized modification in the focal volume, while leaving the surface unaffected. Recent demonstrations of three-dimensional micromachining of glass using femtosecond laser pulses include waveguides [1-9], couplers [10][11][12][13][14], gratings [15][16][17][18][19][20][21][22][23], and three-dimensional binary data storage [24][25][26][27], lenses [28,29], and channels [30][31][32][33]. We present, in this paper, fabrication experiments of three-dimensional photonic devices. Contents of this paper are based on those presented in the International Symposium on Advances and Trends in Fiber Optics and Applications (ATFO 2004), October 11-15, 2004 , Chongqing University, Chongqing, China, and The 6th International Symposium on Laser Precision Microfabrication -SCI-ENCE AND APPLICATIONS -(LPM2005), April 4-8, Williamsburg, Virginia, USA. A 2-mm-long directional coupler to split the optical beam intensities into 1:1 at a wavelength of 632.8 nm is demonstrated [14]. We present in this paper the fabrication experiment of volume gratings induced in silica glass by filamentation of ultrashort laser pulses [17]. We stacked the layers with a period of several microns and fabricated volume gratings. To measure the diffraction efficiency we entered a He-Ne laser beam at the wavelength of 632.8 nm to the grating with the Bragg angle. The maximum diffraction efficiency was 74.8% with the grating that had the period of 3 µm, and the thickness of 150 µm. Fresnel zone plates by embedding voids in silica glass are demonstrated [28]. Holographic data storage on fused silica, soda-lime, and lead glasses with a single 130 fs laser pulse at a wavelength of 800 nm is presented [22]. After the sample is exposed to the interference fringe pattern of the object beam and the reference beam, a relief hologram is recorded through surface ablation. The recorded information can be reconstructed without destruction of the hologram when the power of the reference beam is reduced below the ablation threshold. Finally, we show

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Observation of step-flow growth in femtosecond pulsed laser deposition of Si on Si(100)-2×1

Cited by 12 publications

References 18 publications

Growth of Ge quantum dots on Si(100)-(2×1) by pulsed laser deposition

Growth of Ge quantum dots on Si(100)-(2×1) by pulsed laser deposition

Quantum-dot Infrared Photodetector Fabricated by Pulsed Laser Deposition Technique

Femtosecond Pulsed Laser Deposition of Indium on Si(100)

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