Molecular beam epitaxy of InAs nanowires in SiO2nanotube templates: challenges and prospects for integration of III–Vs on Si (original) (raw)
Related papers
Self-induced growth of vertical free-standing InAs nanowires on Si(111) by molecular beam epitaxy
Nanotechnology, 2010
We report self-induced growth of vertically aligned (i.e. along the [111] direction), free-standing InAs nanowires on Si(111) substrates by solid-source molecular beam epitaxy. Implementation of an ultrathin amorphous SiO x mask on Si(111) facilitated epitaxial InAs nanowire growth, as confirmed by high-resolution x-ray diffraction 2θ-ω scans and transmission electron microscopy. Depending on growth temperature (in the range of 400-520 • C) substantial size variation of both nanowire length and diameter was found under preservation of uniform, non-tapered hexagon-shaped geometries. The majority of InAs nanowires exhibited phase-pure zinc blende crystal structure with few defective regions consisting of stacking faults. Photoluminescence spectroscopy at 20 K revealed peak emission of the InAs nanowires at 0.445 eV, which is ∼30 meV blueshifted with respect to the emission of the bulk InAs reference due to radial quantum confinement effects. These results show a promising route towards integration of well-aligned, high structural quality InAs-based nanowires with the desired aspect ratio and tailored emission wavelengths on an Si platform.
Growth of vertical InAs nanowires on heterostructured substrates
Nanotechnology, 2009
We demonstrate the Au-assisted growth of semiconductor nanowires on different engineered substrates. Two relevant cases are investigated: GaAs/AlGaAs heterostructures capped by a 50 nmthick InAs layer grown by molecular beam epitaxy and a 2 µm-thick InAs buffer layer on Si(111) obtained by vapor phase epitaxy. Morphological and structural properties of substrates and nanowires are analyzed by atomic force and transmission electron microscopy. Our results indicate a promising direction for the integration of III-V nanostructures on Si-based electronics as well as for the development of novel micromechanical structures.
Large-area, catalyst-free heteroepitaxy of InAs nanowires on Si by MOVPE
Physica Status Solidi (A) Applications and Materials Science, 2011
In this paper, we show the results of experiments of InAs nanowire (NW) growth on (111)-oriented Si wafers. The NWs, grown at 620 8C by metal-organic vapor-phase epitaxy, are vertically aligned and $30 nm in diameter. Their structural properties are studied by transmission electron microscopy, evidencing a polytypic character, and the vibrational properties by Raman spectroscopy. An assessment of their electrical transport properties is carried out by measuring back-gated, single InAs NW field-effect transistors. The absence of a catalyst ensures the compatibility of the NW growth process with current CMOS technology.
Growth of III-V semiconductor nanowires by molecular beam epitaxy
Microelectronics Journal, 2009
We present here the growth of GaAs, InAs and InGaAs nanowires by molecular beam epitaxy. The nanowires have been grown on different substrates [GaAs(0 0 1), GaAs , SiO 2 and Si(111)] using gold as the growth catalyst. We show how the different substrates affect the results in terms of nanowire density and morphology. We also show that the growth temperature for the InGaAs nanowires has to be carefully chosen to obtain homogeneous alloys.
Molecular beam epitaxy of InN nanowires on si
Journal of Crystal Growth, 2015
We report on a systematic growth study of the nucleation process of InN nanowires on Si(1 1 1) substrates using plasma assisted molecular beam epitaxy (PAMBE). Samples are grown with various substrate temperatures and III/V ratios. Scanning electron microscopy, X-ray diffraction spectroscopy, energy dispersive X-ray spectroscopy, and photoluminescence are carried out to map out the variation in structural and optical properties versus growth conditions. Statistical averages of areal density, height, and radius are mapped as a function of substrate temperature and III/V ratio. Three different morphological phases are identified on the growth surface: InN, α-In and β-In. Based on SEM image analysis of samples grown at different conditions, the formation mechanism of these phases is proposed. Finally, the growth phase diagram of PAMBE grown InN on Si under N-rich condition is presented, and tapered versus non-tapered growth conditions are identified. It is found that high growth temperature and low III/V ratio plays a critical role in the growth of non-tapered InN nanowires.
Advanced Materials, 2007
The material properties of III-V semiconductors are in many ways superior to those of Si. Examples of these properties are the possibilities for high electron mobilities and the direct bandgap in most III-V semiconductors. Even so, Si remains the standard material in the electronics industry. A successful combination of these two material systems would add new functionality and increased performance compared to standard Si technology. Although these advantages have long been recognized, the monolithic integration of devicequality III-V materials on Si remains a major challenge. In this work, we report on heteroepitaxial growth of InAs nanowires (NWs) directly on Si substrates by employing self-assembled organic coatings to create an oxide template that guides NW nucleation. Such a template resembles the growth masks used in selective-area epitaxy of nanostructures on III-V substrates. Importantly, Au, which is commonly used for NW synthesis but not compatible with modern complementary metal oxide semiconductor (CMOS) processing, is avoided. The described nucleation method presents clear advantages in terms of epitaxial quality and control of NW size and density distributions compared to previous results achieved on Si using catalyst-free NW growth. The control demonstrated in the fields of self-assembled and printed organic nanostructures illustrates how the method may be extended to more complex patterning in future work.
On the growth of InAs nanowires by molecular beam epitaxy
Journal of Crystal Growth, 2011
The growth of InAs nanowires by molecular beam epitaxy only takes place in a narrow temperature range, independent of the method used to induce the growth: with (Au or Mn) or without metal catalysts. Our findings suggest that the physical chemistry of the intermetallic compound formed during the catalyzed growth of the NWs is not relevant for the induction of the growth. Moreover, the lattice structure of the wires always shows wurtzite sections. Our results indicate the need of a unified model for the metal-catalyzed and self-catalyzed growth of nanowires.
Self-catalyzed InAs nanowires grown on Si: the key role of kinetics on their morphology
Nanotechnology
Integrating self-catalyzed InAs nanowires on Si(111) is an important step toward building vertical gate-all-around transistors. The CMOS compatibility and the nanowire aspect ratio are two crucial parameters to consider. In this work, we optimize the InAs nanowire morphology by changing the growth mode from Vapor-Solid to Vapor-Liquid-Solid in a CMOS compatible process. We study the key role of the Hydrogen surface preparation on nanowire growths and bound it to a change of the chemical potential and adatoms diffusion length on the substrate. We transfer the optimized process to patterned wafers and adapt both the surface preparation and the growth conditions. Once group III and V fluxes are balances, aspect ratio can be improved by increasing the system kinetics. Overall, we propose a method for large scale integration of CMOS compatible InAs nanowire on silicon and highlight the major role of kinetics on the growth mechanism.
Inhomogeneous Si-doping of gold-seeded InAs nanowires grown by molecular beam epitaxy
Applied Physics Letters, 2013
We have investigated in-situ Si doping of InAs nanowires grown by molecular beam epitaxy from gold seeds. The effectiveness of n-type doping is confirmed by electrical measurements showing an increase of the electron density with the Si flux. We also observe an increase of the electron density along the nanowires from the tip to the base, attributed to the dopant incorporation on the nanowire facets whereas no detectable incorporation occurs through the seed. Furthermore the Si incorporation strongly influences the lateral growth of the nanowires without giving rise to significant tapering, revealing the complex interplay between axial and lateral growth.
Vertical III–V Nanowire Device Integration on Si(100)
Nano Letters, 2014
We report complementary metal−oxide−semiconductor (CMOS)-compatible integration of compound semiconductors on Si substrates. InAs and GaAs nanowires are selectively grown in vertical SiO 2 nanotube templates fabricated on Si substrates of varying crystallographic orientations, including nanocrystalline Si. The nanowires investigated are epitaxially grown, single-crystalline, free from threading dislocations, and with an orientation and dimension directly given by the shape of the template. GaAs nanowires exhibit stable photoluminescence at room temperature, with a higher measured intensity when still surrounded by the template. Si−InAs heterojunction nanowire tunnel diodes were fabricated on Si(100) and are electrically characterized. The results indicate a high uniformity and scalability in the fabrication process.