Monolithic integration of optical grade GaAs on Si (001) substrates deeply patterned at a micron scale (original) (raw)
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Nanoscale Growth of GaAs on Patterned Si(111) Substrates by Molecular Beam Epitaxy
High-quality and defect-free GaAs were successfully grown via molecular beam epitaxy on silicon dioxide patterned Si(111) substrates by a two-step growth technique. Compared with the one-step approach, the two-step growth scheme has been found to be a better pathway to obtain a superior-quality GaAs on Si. Taking advantages of low energy for both Si(111) surface and GaAs/Si(111) interface, the two-step grown GaAs of total 175 nm atop patterned Si(111) substrates exhibits atomically smooth surface morphology, single crystallininty and a remarkably low defect density. A low-temperature GaAs nucleation layer of the two-step growth helps relieve the misfit stress by accommodating the misfit dislocations at the very adjacent GaAs/Si interface. The excellent properties of the two-step grown GaAs were investigated and verified by field-emission scanning electron microscopy, atomic force microscopy, X-ray diffraction, transmission electron microscopy, and Raman spectroscopy. Finally we demonstrated a GaAs on Si solar cell, which could represent an important milestone for future applications in light-emitting diodes, lasers, and photodetectors on Si.
Journal of Crystal Growth, 2008
Selective deposition of GaAs-based microstructures on a patterned SiO 2 /GaAs substrate was realized by molecular beam epitaxy. The growth mechanism was investigated experimentally by studying both the diffusion and desorption mechanisms of GaAs on SiO 2 surfaces. A model describing the diffusion and desorption of adatoms on the patterned surface is presented. The theoretical considerations are used to determine experimentally the diffusion length and the sticking coefficient of Ga(As) on SiO 2 as a function of temperature. The growth results are applied to the fabrication of GaAs-based quantum well microsctructures. Finally, the optical properties of InGaAs and AlGaAs heterostructures were examined by micro-photoluminescence spectroscopy, indicating the good quality of the material deposited by this method. r
Kinetic growth mode of epitaxial GaAs on Si(001) micro-pillars
Journal of Applied Physics, 2016
Three-dimensional, epitaxial GaAs crystals are fabricated on micro-pillars patterned into Si(001) substrates by exploiting kinetically controlled growth conditions in Molecular Beam Epitaxy. The evolution of crystal morphology during growth is assessed by considering samples with increasing GaAs deposit thickness. Experimental results are interpreted by a kinetic growth model, which takes into account the fundamental aspects of the growth and mutual deposition flux shielding between neighboring crystals. Different substrate pattern geometries with dissimilar lateral sizes and periodicities of the Si micro-pillars are considered and self-similar crystal structures are recognized. It is demonstrated that the top faceting of the GaAs crystals is tunable, which can pave the way to locally engineer compound semiconductor quantum structures on Si(001) substrates.
Wafer-fused orientation-patterned GaAs
2008
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GaAs on Si(111)—crystal shape and strain relaxation in nanoscale patterned growth
Applied Physics Letters, 2005
Nanoscale patterned growth of GaAs on Si͑111͒ by molecular beam epitaxy is examined. A 355 nm period two-dimensional array of circular holes ͑diameter ϳ200-250 nm͒ is fabricated into a 45-nm-thick SiO 2 film on a Si͑111͒ substrate by large-area interferometric lithography and dry etching. For 300 nm deposition, the GaAs epilayer selectively deposited within each hole on the patterned substrate is surrounded by ͕110͖-type sidewalls perpendicular to Si͑111͒, resulting in a hexagon-based prismatic pillar, without significant lateral overgrowth. At the initial stage of growth, twins parallel to Si͑111͒ and an aperiodic mixture of cubic and hexagonal phases are observed but most of the GaAs pillars are terminated with a cubic phase region. Raman scattering reveals that the individual nanoscale GaAs pillars are completely strain relaxed.
Dynamical faceting and nanoscale lateral growth of GaAs by molecular beam epitaxy
Journal of Crystal Growth, 2002
Dynamical faceting during homoepitaxial growth of GaAs on nanoscale-patterned surfaces by molecular beam epitaxy is examined. Selective deposition on open GaAs(1 0 0) surfaces with lateral dimensions ranging from 130 to 250 nm, separated by 15-80 nm-wide (25-nm-thick) SiO 2 stripes aligned along the ½0 % 1 1 direction results in facet formation and lateral growth over the SiO 2 mask. At the early stage of growth, (3 1 1) facets appear on sidewalls near the boundary between an open GaAs surface and SiO 2 mask, these are replaced by (1 1 1) facets starting from SiO 2 boundaries as growth continues. After complete replacement, growth proceeds laterally in the direction perpendicular to ½0 % 1 1 retaining the (1 1 1) facets until coalescence occurs between adjacent triangular cross-sectioned GaAs stripes. Nanoscale fabrication nonuniformity results in dynamical formation and retention of multiple (3 1 1) facets even for growth thicknesses much greater than the thickness of the SiO 2 mask stripes. This dynamical faceting is interpreted by minimization of total surface free energy based on equilibrium crystal shape, in qualitative agreement with our experimental results. r