We report on the formation of large-area ordered Ge-Si compound quantum dot molecules (CQDMs) in ... more We report on the formation of large-area ordered Ge-Si compound quantum dot molecules (CQDMs) in a combination of nanosphere lithography and self-assembly. Truncated-pyramidlike Si dots with {11n} facets are readily formed, which are spatially ordered in a large area with controlled period and size. Each Si dot induces four self-assembled Ge-rich dots at its base edges that can be fourfold symmetric along <110> directions. A model based on surface chemical potential accounts well for these phenomena. Our results disclose the critical effect of surface curvature on the diffusion and the aggregation of Ge adatoms and shed new light on the unique features and the inherent mechanism of self-assembled QDs on patterned substrates. Such a configuration of one Si QD surrounded by fourfold symmetric Ge-rich QDs can be seen as a CQDM with unique features, which will have potential applications in novel devices.
An easy approach to fabricate ordered pattern using nanosphere lithography and reactive iron etch... more An easy approach to fabricate ordered pattern using nanosphere lithography and reactive iron etching technology was demonstrated. Long-range ordered GeSi nanorings with 430 nm period were grown on patterned Si (001) substrates by molecular beam epitaxy. The size and shape of rings were closely associated with the size of capped GeSi quantum dots and the Si capping processes. Statistical analysis on the lateral size distribution shows that the high growth temperature and the long-term annealing can improve the uniformity of nanorings.
We report on optical properties of coupled three-dimensional (3D) Ge quantum dot crystals (QDCs).... more We report on optical properties of coupled three-dimensional (3D) Ge quantum dot crystals (QDCs). With increasing the vertical periodic number of the QDCs, the photoluminescence (PL) spectral linewidth decreased exponentially, and so did the peak energy blueshift caused by increasing excitation power, which are attributed to the electronic coupling and thus the formation of miniband. In the PL spectra, the relative intensity of the transverse-optical (TO) phonon replica also decreases with increasing the vertical periodic number, which is attributed to the increased Brillouin-zone folding effect in vertical direction and therewith the relaxation of indirect transition nature of exciton recombination. Besides, the optical reflectivity at the interband transition energy was much more reduced for the QDCs than for the in-plane disordered QDs grown with the same parameters, indicating a higher interband absorption of the QDCs due to the miniband formation.
Unimodal SiGe islands with dominant f111g facets were grown coherently on pit-patterned Si (001) ... more Unimodal SiGe islands with dominant f111g facets were grown coherently on pit-patterned Si (001) substrates by molecular beam epitaxy. With increasing Ge deposition, the f111g pyramids evolve from dome-shaped islands, reaching significantly larger volumes than are coherently possible on flat substrates. Finite element calculations and molecular dynamics simulations show that SiGe islands in pits can have less misfit strain with respect to islands of the same shape on flat substrates. The injection of dislocations is thus delayed, allowing for the observed development of coherent islands with a very high aspect ratio.
Recent Advances in Nanofabrication Techniques and Applications, 2011
... RG (1996) Self-Assembly of a Two-Dimensional Superlattice of Molecularly Linked Metal Cluster... more ... RG (1996) Self-Assembly of a Two-Dimensional Superlattice of Molecularly Linked Metal Clusters. ... Fu, LW; Patoka, P.; Kandulski, W.; Giersig, M.; &amp; Giessen, H. (2009) Periodic Large-Area Metallic Split ... 406, 1027-1031 Kim, JJ;Li, Y.; Lee, EJ; § Cho, SO (2009) Fabrication of Size ...
2010 3rd International Nanoelectronics Conference (INEC), 2010
Ordered GeSi nanoislands were fabricated in combination of self-assembly and nanosphere lithograp... more Ordered GeSi nanoislands were fabricated in combination of self-assembly and nanosphere lithography on Si (001) substrates. Well ordered pits in a hexagonal lattice on Si (001) substrates are readily obtained via nanosphere lithography. The preferential nucleation of GeSi nanoislands in the pits results in laterally ordered nanoislands on such prepatterned Si (001) surface during Ge deposition. Multilayer GeSi nanoislands separated
In this Article, we report the successful fabrication of large-area ordered Si nanowire arrays (N... more In this Article, we report the successful fabrication of large-area ordered Si nanowire arrays (NWAs) by a cost-effective and scalable wet-etching process in combination with nanospheres lithography technique. The periodical Si NWAs are further investigated as photocathode for water splitting, with excellent hydrogen evolution performances with a maximum photocurrent density of 27 mA cm(-2) achieved, which is ∼2.5 times that of planar Si and random Si nanowires electrode. The greatly improved PEC performance can be attributed to the patterned and ordered NWs structure as a result of enhancement of the light harvesting as well as charge transportation and collection efficiency.
Photogenerated charging properties of single Si nanorods (Si NRs) are investigated by electrostat... more Photogenerated charging properties of single Si nanorods (Si NRs) are investigated by electrostatic force microscopy (EFM) combined with laser irradiation. Under laser irradiation, Si NRs are positively charged. The amount of the charges trapped in single NRs as well as the contact potential difference between the tip and NRs' surface is achieved from an analytical fitting of the phase shift -voltage curve. Both of them significantly vary with the laser intensity and the NR's size and construction. The photogenerated charging and decharging rates are obtained at a timescale of seconds or slower, indicating that the Si NRs are promising candidates in photovoltaic applications.
The reflectance of the controlled periodic Si nanowire (NW) arrays is systematically explored, wh... more The reflectance of the controlled periodic Si nanowire (NW) arrays is systematically explored, which characterizes the influence on the solar energy harnessing ability by the geometries of the NW. A unique dependence of the reflectance of the Si NW array on the diameter, the height, and the bending of the NW are disclosed. The solar energy loss caused by the reflection of the Si NW array exhibits the minimum for the NW with intermediate diameter and length. A plane-wave-based transfer-matrix method (TMM) simulation is performed, which is well consistent with the experimental results. Our results demonstrate the design principle to optimize the Si NW arrays for high-efficiency solar cells. 81.07.-b; 78.67.-n; 81.16.-c.
ABSTRACT The layered GeSi quantum dots (QDs) are grown on (001) Si substrate by molecular beam ep... more ABSTRACT The layered GeSi quantum dots (QDs) are grown on (001) Si substrate by molecular beam epitaxy. The photoluminescence (PL) peak of the as-grown GeSi quantum dots has obvious blue shift and enhancement after processed by ion implantation and rapid thermal annealing. It is indicated that the blue shift is originated from the interdiffusion of Ge and Si at the interface between QDs and the surrounding matrix. The dependence of PL intensity on the excitation power shows that there are the nonradiative centers of shallow local energy levels from the point defects caused by the ion implantation, but not removed by the rapid thermal annealing. The tunable blue shift of the PL position from the 1300 nm to 1500 nm region may have significant application value in the optical communication.
A quantitative structural model, based on x-ray diffraction, is provided to analyze quadruple-per... more A quantitative structural model, based on x-ray diffraction, is provided to analyze quadruple-period atomic ordering along ͓110͔ in a GaAs 0.87 Sb 0.13 alloy grown on a ͑001͒ GaAs substrate by molecular beam epitaxy. To minimize the local strain energy derived by a valence force field ͑VFF͒ model for the alloy, atomic displacements were deduced and incorporated in our model. Calculation of the scattering pattern based on the model agrees well with experiment. We propose that this ordering originates from a (2ϫ4) surface reconstruction and the difference in properties of the atomic species.
A novel circularly arranged structure of germanium quantum dots has been fabricated by combining ... more A novel circularly arranged structure of germanium quantum dots has been fabricated by combining techniques including electron beam lithography, wet etching and molecular beam epitaxy. It was observed that both pattern and growth parameters affect the morphology of the quantum dot molecules. Meanwhile, the oxidation mask plays a vital role in the formation of circularly organized quantum dots. The experimental
Physica E: Low-dimensional Systems and Nanostructures, 2004
Stacks of Ge islands layers, separated by thin Si spacer layers, have been grown on prepatterned ... more Stacks of Ge islands layers, separated by thin Si spacer layers, have been grown on prepatterned Si (0 0 1) substrates. The sample topography, obtained by atomic force microscopy, exhibits a regular two-dimensional island arrangement. The vertical alignment is conÿrmed in cross-sectional transmission electron microscopy images. X-ray di raction reciprocal space maps around the (0 0 4) Bragg point reveal exceptional lateral and vertical ordering of the Ge islands. Photoluminescence spectra taken at 5 K show well-separated peaks of the no-phonon and the transverse-optical phonon replica of these ordered islands, which is achieved too, due to the excellent island size uniformity. ?
Physica E: Low-dimensional Systems and Nanostructures, 2004
We report on the growth and properties of Ge islands grown on (0 0 1) Si substrates with lithogra... more We report on the growth and properties of Ge islands grown on (0 0 1) Si substrates with lithographically defined two-dimensionally periodic pits. After thermal desorption and a subsequent Si buffer layer growth these pits have an inverted truncated pyramid shape. We observe that on such prepatterned substrates lens-like Ge-rich islands grow at the pit bottoms with less Ge deposition than necessary for island formation on flat substrates. This is attributed to the aggregation of Ge at the bottom of the pits, due to Ge migration from the pit sidewalls. At the later stages of growth, dome-like islands with dominant f1; 1; 3g or f15; 3; 23g; or other high-index facets [i.e. f15; 3; 20g facets] are formed on the patterned substrates as shown by surface orientation maps using atomic force microscopy. Furthermore, larger coherent islands can be grown on patterned substrates as compared to Ge deposition on flat ones. r . Cross-sectional TEM image of 10 ML Ge deposition sample P 10 :
A new scalable approach has been developed for fabricating large-scale pit patterns with controll... more A new scalable approach has been developed for fabricating large-scale pit patterns with controllable periodicity on Si(001) substrates. The fabrication processes start with selfassembling a monolayer of polystyrene (PS) spheres on hydrogenated Si(001) substrates. A novel net-like mask in combination of the Au pattern thermally evaporated in between the PS spheres and the Au-catalyzed SiO 2 around them is naturally formed. After selective etching of Si by KOH solution, two-dimensionally ordered pits with a periodicity equal to the diameter of the PS spheres in the range from micrometers to less than 100 nm can be obtained. The shape of the pits can be modulated by controlling the chemical etching time. Such pit-patterned Si substrates facilitate the formation of ordered Si-based nanostructures, such as ordered self-assembled GeSi quantum dots, by deposition of Ge using molecular beam epitaxy.
Multilayer ordered GeSi quantum dots (QDs) with thin Si spacers were obtained via self-assembly o... more Multilayer ordered GeSi quantum dots (QDs) with thin Si spacers were obtained via self-assembly on pit-patterned Si(001) substrates. The lateral ordering of GeSi QDs predetermined by the periodic pit pattern results in remarkably improved size uniformity in comparison with random QDs on flat substrates. A much stronger and narrower photoluminescence (PL) peak from ordered QDs were observed than that from random ones, particularly at high excitation power. Such enhanced PL signal was attributed to the high density of states and the uniform distribution of excitons in the ordered and uniform QDs, which can efficiently suppress the Auger effect and the Coulomb screening effect. Moreover, anomalous narrowing of the PL peak from the ordered QDs with the excitation power was observed, which was explained in terms of distributed feedback associated with the periodic stacked GeSi QDs.
Controlled SiGe coaxial quantum wells (CQWs) on periodic Si(001) nanopillars in a large area are ... more Controlled SiGe coaxial quantum wells (CQWs) on periodic Si(001) nanopillars in a large area are explored systematically. The periodic SiGe CQW nanopillars are fabricated by a combination of nanosphere lithography, metal assisted chemical etching and epitaxial growth. The period, the radius, the height, the composition and the thickness of the SiGe alloy layer can all be intentionally modified. Considerably enhanced photoluminescence (PL) from the SiGe CQW nanopillars is observed, which is composed of four peaks. Such PL features are explained by the coupling between the spontaneous emissions of the SiGe CQW and the Mie resonant modes of the nanopillars, which can be further improved by optimizing the structural parameters of the SiGe CQW and the nanopillars. Our results demonstrate a feasible route to obtaining controlled SiGe CQW nanopillars, which have potential applications in optoelectronic devices.
Very small and compactly arranged GeSi nanowires could self-assembled on vicinal Si (001) substra... more Very small and compactly arranged GeSi nanowires could self-assembled on vicinal Si (001) substrates with~8°off toward 〈110〉 during Ge deposition. The nanowires were all oriented along the miscut direction. The small ration of height over width of the nanowire indicated that the nanowires were bordered partly with {1 0 5} facets. These self-assembled small nanowires were remarkably influenced by the growth conditions and the miscut angle of substrates in comparison with large dome-like islands obtained after sufficient Ge deposition. These results proposed that the formation of the nanowire was energetically driven under growth kinetic assistance. Threedimensionally self-assembled GeSi nanowires were first realized via multilayer Ge growth separated with Si spacers. These GeSi nanowires were readily embedded in Si matrix and compatible with the sophisticated Si technology, which suggested a feasible strategy to fabricate nanowires for fundamental studies and a wide variety of applications.
We report on the formation of large-area ordered Ge-Si compound quantum dot molecules (CQDMs) in ... more We report on the formation of large-area ordered Ge-Si compound quantum dot molecules (CQDMs) in a combination of nanosphere lithography and self-assembly. Truncated-pyramidlike Si dots with {11n} facets are readily formed, which are spatially ordered in a large area with controlled period and size. Each Si dot induces four self-assembled Ge-rich dots at its base edges that can be fourfold symmetric along <110> directions. A model based on surface chemical potential accounts well for these phenomena. Our results disclose the critical effect of surface curvature on the diffusion and the aggregation of Ge adatoms and shed new light on the unique features and the inherent mechanism of self-assembled QDs on patterned substrates. Such a configuration of one Si QD surrounded by fourfold symmetric Ge-rich QDs can be seen as a CQDM with unique features, which will have potential applications in novel devices.
An easy approach to fabricate ordered pattern using nanosphere lithography and reactive iron etch... more An easy approach to fabricate ordered pattern using nanosphere lithography and reactive iron etching technology was demonstrated. Long-range ordered GeSi nanorings with 430 nm period were grown on patterned Si (001) substrates by molecular beam epitaxy. The size and shape of rings were closely associated with the size of capped GeSi quantum dots and the Si capping processes. Statistical analysis on the lateral size distribution shows that the high growth temperature and the long-term annealing can improve the uniformity of nanorings.
We report on optical properties of coupled three-dimensional (3D) Ge quantum dot crystals (QDCs).... more We report on optical properties of coupled three-dimensional (3D) Ge quantum dot crystals (QDCs). With increasing the vertical periodic number of the QDCs, the photoluminescence (PL) spectral linewidth decreased exponentially, and so did the peak energy blueshift caused by increasing excitation power, which are attributed to the electronic coupling and thus the formation of miniband. In the PL spectra, the relative intensity of the transverse-optical (TO) phonon replica also decreases with increasing the vertical periodic number, which is attributed to the increased Brillouin-zone folding effect in vertical direction and therewith the relaxation of indirect transition nature of exciton recombination. Besides, the optical reflectivity at the interband transition energy was much more reduced for the QDCs than for the in-plane disordered QDs grown with the same parameters, indicating a higher interband absorption of the QDCs due to the miniband formation.
Unimodal SiGe islands with dominant f111g facets were grown coherently on pit-patterned Si (001) ... more Unimodal SiGe islands with dominant f111g facets were grown coherently on pit-patterned Si (001) substrates by molecular beam epitaxy. With increasing Ge deposition, the f111g pyramids evolve from dome-shaped islands, reaching significantly larger volumes than are coherently possible on flat substrates. Finite element calculations and molecular dynamics simulations show that SiGe islands in pits can have less misfit strain with respect to islands of the same shape on flat substrates. The injection of dislocations is thus delayed, allowing for the observed development of coherent islands with a very high aspect ratio.
Recent Advances in Nanofabrication Techniques and Applications, 2011
... RG (1996) Self-Assembly of a Two-Dimensional Superlattice of Molecularly Linked Metal Cluster... more ... RG (1996) Self-Assembly of a Two-Dimensional Superlattice of Molecularly Linked Metal Clusters. ... Fu, LW; Patoka, P.; Kandulski, W.; Giersig, M.; &amp; Giessen, H. (2009) Periodic Large-Area Metallic Split ... 406, 1027-1031 Kim, JJ;Li, Y.; Lee, EJ; § Cho, SO (2009) Fabrication of Size ...
2010 3rd International Nanoelectronics Conference (INEC), 2010
Ordered GeSi nanoislands were fabricated in combination of self-assembly and nanosphere lithograp... more Ordered GeSi nanoislands were fabricated in combination of self-assembly and nanosphere lithography on Si (001) substrates. Well ordered pits in a hexagonal lattice on Si (001) substrates are readily obtained via nanosphere lithography. The preferential nucleation of GeSi nanoislands in the pits results in laterally ordered nanoislands on such prepatterned Si (001) surface during Ge deposition. Multilayer GeSi nanoislands separated
In this Article, we report the successful fabrication of large-area ordered Si nanowire arrays (N... more In this Article, we report the successful fabrication of large-area ordered Si nanowire arrays (NWAs) by a cost-effective and scalable wet-etching process in combination with nanospheres lithography technique. The periodical Si NWAs are further investigated as photocathode for water splitting, with excellent hydrogen evolution performances with a maximum photocurrent density of 27 mA cm(-2) achieved, which is ∼2.5 times that of planar Si and random Si nanowires electrode. The greatly improved PEC performance can be attributed to the patterned and ordered NWs structure as a result of enhancement of the light harvesting as well as charge transportation and collection efficiency.
Photogenerated charging properties of single Si nanorods (Si NRs) are investigated by electrostat... more Photogenerated charging properties of single Si nanorods (Si NRs) are investigated by electrostatic force microscopy (EFM) combined with laser irradiation. Under laser irradiation, Si NRs are positively charged. The amount of the charges trapped in single NRs as well as the contact potential difference between the tip and NRs' surface is achieved from an analytical fitting of the phase shift -voltage curve. Both of them significantly vary with the laser intensity and the NR's size and construction. The photogenerated charging and decharging rates are obtained at a timescale of seconds or slower, indicating that the Si NRs are promising candidates in photovoltaic applications.
The reflectance of the controlled periodic Si nanowire (NW) arrays is systematically explored, wh... more The reflectance of the controlled periodic Si nanowire (NW) arrays is systematically explored, which characterizes the influence on the solar energy harnessing ability by the geometries of the NW. A unique dependence of the reflectance of the Si NW array on the diameter, the height, and the bending of the NW are disclosed. The solar energy loss caused by the reflection of the Si NW array exhibits the minimum for the NW with intermediate diameter and length. A plane-wave-based transfer-matrix method (TMM) simulation is performed, which is well consistent with the experimental results. Our results demonstrate the design principle to optimize the Si NW arrays for high-efficiency solar cells. 81.07.-b; 78.67.-n; 81.16.-c.
ABSTRACT The layered GeSi quantum dots (QDs) are grown on (001) Si substrate by molecular beam ep... more ABSTRACT The layered GeSi quantum dots (QDs) are grown on (001) Si substrate by molecular beam epitaxy. The photoluminescence (PL) peak of the as-grown GeSi quantum dots has obvious blue shift and enhancement after processed by ion implantation and rapid thermal annealing. It is indicated that the blue shift is originated from the interdiffusion of Ge and Si at the interface between QDs and the surrounding matrix. The dependence of PL intensity on the excitation power shows that there are the nonradiative centers of shallow local energy levels from the point defects caused by the ion implantation, but not removed by the rapid thermal annealing. The tunable blue shift of the PL position from the 1300 nm to 1500 nm region may have significant application value in the optical communication.
A quantitative structural model, based on x-ray diffraction, is provided to analyze quadruple-per... more A quantitative structural model, based on x-ray diffraction, is provided to analyze quadruple-period atomic ordering along ͓110͔ in a GaAs 0.87 Sb 0.13 alloy grown on a ͑001͒ GaAs substrate by molecular beam epitaxy. To minimize the local strain energy derived by a valence force field ͑VFF͒ model for the alloy, atomic displacements were deduced and incorporated in our model. Calculation of the scattering pattern based on the model agrees well with experiment. We propose that this ordering originates from a (2ϫ4) surface reconstruction and the difference in properties of the atomic species.
A novel circularly arranged structure of germanium quantum dots has been fabricated by combining ... more A novel circularly arranged structure of germanium quantum dots has been fabricated by combining techniques including electron beam lithography, wet etching and molecular beam epitaxy. It was observed that both pattern and growth parameters affect the morphology of the quantum dot molecules. Meanwhile, the oxidation mask plays a vital role in the formation of circularly organized quantum dots. The experimental
Physica E: Low-dimensional Systems and Nanostructures, 2004
Stacks of Ge islands layers, separated by thin Si spacer layers, have been grown on prepatterned ... more Stacks of Ge islands layers, separated by thin Si spacer layers, have been grown on prepatterned Si (0 0 1) substrates. The sample topography, obtained by atomic force microscopy, exhibits a regular two-dimensional island arrangement. The vertical alignment is conÿrmed in cross-sectional transmission electron microscopy images. X-ray di raction reciprocal space maps around the (0 0 4) Bragg point reveal exceptional lateral and vertical ordering of the Ge islands. Photoluminescence spectra taken at 5 K show well-separated peaks of the no-phonon and the transverse-optical phonon replica of these ordered islands, which is achieved too, due to the excellent island size uniformity. ?
Physica E: Low-dimensional Systems and Nanostructures, 2004
We report on the growth and properties of Ge islands grown on (0 0 1) Si substrates with lithogra... more We report on the growth and properties of Ge islands grown on (0 0 1) Si substrates with lithographically defined two-dimensionally periodic pits. After thermal desorption and a subsequent Si buffer layer growth these pits have an inverted truncated pyramid shape. We observe that on such prepatterned substrates lens-like Ge-rich islands grow at the pit bottoms with less Ge deposition than necessary for island formation on flat substrates. This is attributed to the aggregation of Ge at the bottom of the pits, due to Ge migration from the pit sidewalls. At the later stages of growth, dome-like islands with dominant f1; 1; 3g or f15; 3; 23g; or other high-index facets [i.e. f15; 3; 20g facets] are formed on the patterned substrates as shown by surface orientation maps using atomic force microscopy. Furthermore, larger coherent islands can be grown on patterned substrates as compared to Ge deposition on flat ones. r . Cross-sectional TEM image of 10 ML Ge deposition sample P 10 :
A new scalable approach has been developed for fabricating large-scale pit patterns with controll... more A new scalable approach has been developed for fabricating large-scale pit patterns with controllable periodicity on Si(001) substrates. The fabrication processes start with selfassembling a monolayer of polystyrene (PS) spheres on hydrogenated Si(001) substrates. A novel net-like mask in combination of the Au pattern thermally evaporated in between the PS spheres and the Au-catalyzed SiO 2 around them is naturally formed. After selective etching of Si by KOH solution, two-dimensionally ordered pits with a periodicity equal to the diameter of the PS spheres in the range from micrometers to less than 100 nm can be obtained. The shape of the pits can be modulated by controlling the chemical etching time. Such pit-patterned Si substrates facilitate the formation of ordered Si-based nanostructures, such as ordered self-assembled GeSi quantum dots, by deposition of Ge using molecular beam epitaxy.
Multilayer ordered GeSi quantum dots (QDs) with thin Si spacers were obtained via self-assembly o... more Multilayer ordered GeSi quantum dots (QDs) with thin Si spacers were obtained via self-assembly on pit-patterned Si(001) substrates. The lateral ordering of GeSi QDs predetermined by the periodic pit pattern results in remarkably improved size uniformity in comparison with random QDs on flat substrates. A much stronger and narrower photoluminescence (PL) peak from ordered QDs were observed than that from random ones, particularly at high excitation power. Such enhanced PL signal was attributed to the high density of states and the uniform distribution of excitons in the ordered and uniform QDs, which can efficiently suppress the Auger effect and the Coulomb screening effect. Moreover, anomalous narrowing of the PL peak from the ordered QDs with the excitation power was observed, which was explained in terms of distributed feedback associated with the periodic stacked GeSi QDs.
Controlled SiGe coaxial quantum wells (CQWs) on periodic Si(001) nanopillars in a large area are ... more Controlled SiGe coaxial quantum wells (CQWs) on periodic Si(001) nanopillars in a large area are explored systematically. The periodic SiGe CQW nanopillars are fabricated by a combination of nanosphere lithography, metal assisted chemical etching and epitaxial growth. The period, the radius, the height, the composition and the thickness of the SiGe alloy layer can all be intentionally modified. Considerably enhanced photoluminescence (PL) from the SiGe CQW nanopillars is observed, which is composed of four peaks. Such PL features are explained by the coupling between the spontaneous emissions of the SiGe CQW and the Mie resonant modes of the nanopillars, which can be further improved by optimizing the structural parameters of the SiGe CQW and the nanopillars. Our results demonstrate a feasible route to obtaining controlled SiGe CQW nanopillars, which have potential applications in optoelectronic devices.
Very small and compactly arranged GeSi nanowires could self-assembled on vicinal Si (001) substra... more Very small and compactly arranged GeSi nanowires could self-assembled on vicinal Si (001) substrates with~8°off toward 〈110〉 during Ge deposition. The nanowires were all oriented along the miscut direction. The small ration of height over width of the nanowire indicated that the nanowires were bordered partly with {1 0 5} facets. These self-assembled small nanowires were remarkably influenced by the growth conditions and the miscut angle of substrates in comparison with large dome-like islands obtained after sufficient Ge deposition. These results proposed that the formation of the nanowire was energetically driven under growth kinetic assistance. Threedimensionally self-assembled GeSi nanowires were first realized via multilayer Ge growth separated with Si spacers. These GeSi nanowires were readily embedded in Si matrix and compatible with the sophisticated Si technology, which suggested a feasible strategy to fabricate nanowires for fundamental studies and a wide variety of applications.
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