Growth kinetics in position-controlled and catalyst-free InAs nanowire arrays on Si(111) grown by selective area molecular beam epitaxy

Abstract

We investigated the interwire distance dependence on the growth kinetics of vertical, high-yield InAs nanowire arrays on Si(111) grown by catalyst-free selective area molecular beam epitaxy (MBE). Utilizing lithographically defined SiO2 nanomasks on Si(111) with regular hole patterns, catalyst-free and site-selective growth of vertically (111)-oriented InAs nanowires was achieved with very high yields of ∼90 percent. Interestingly, the yield of vertically ordered nanowires was independent of the interwire distance and the initial growth stages. Significant size variation in the nanowires was found to depend critically on the interwire distance and growth time. Two growth regimes were identified—(i) a competitive growth regime with shorter and thinner nanowires for narrow interwire distances and (ii) a diffusion-limited growth regime for wider distances, providing good estimates for the surface diffusion lengths. Surprisingly, despite these size-dependent effects the nanowire geometries remained unaltered with uniform, almost nontapered morphologies even over large variation in nanowire density (∼mid−106–109 cm−2 range). X-ray diffraction further confirmed the vertical (111) directionality with low crystal tilt by rocking curve widths (ω scans) as low as ∼0.6°. These findings demonstrate the capability to precisely tailor the position and size of well-oriented III-V semiconductor nanowires through noncatalytic MBE selective area growth and provide an important step toward fully integrated, uniform vertical III-V nanowire array-on-Si devices.

Influence of the adatom diffusion on selective growth of GaN nanowire regular arrays

“…Comparing this with the axial growth rate estimated about 7 nm/min, the radial growth rate is more than one order of magnitude smaller than the axial growth rate; similarly to that already reported for NW growth on bare Si substrates 17 ͑5 nm/min and 0.15 nm/min for axial and radial growth rates, respectively͒. Similar length and diameter behaviors are observed as well for other material systems grown in absence of a catalyst, 28 whereas SAG in vapor-liquid-solid conditions leads to different dependences. 29,30 The length and diameter were used to calculate the volume of the NWs assuming a cylindrical shape.…”

Lasing from individual GaAs-AlGaAs core-shell nanowires up to room temperature

“…The GaAs-AlGaAs core-shell NWs were grown using solid source MBE on Si(111) substrates that were thermally oxidized to produce a 20 ± 1-nm-thick SiO 2 mask layer. Before growth, the oxide was thinned using an aqueous, dilute NH 4 -HF solution to produce a B2-nm-thick SiO 2 layer containing pinholes to the Si(111) substrate, which act as nucleation sites for NW growth 23,24,45,46 . The prepared substrates were then transferred into a Gen II MBE system and held at 700°C for 20 min to remove surface contaminants before being cooled to the nominal growth temperature of 610°C.…”

Characterization and analysis of InAs/p–Si heterojunction nanowire-based solar cell

“…InAs nanowire arrays were grown by molecular beam epitaxy in a DCA P600 system, following recent works [15,36]. They were grown on 275 µm thick Czochralski 1 1 1 p-doped Si wafers with a resistivity of 10-20 cm.…”

“…Vertical orientation of nanowires can be achieved on Si (1 1 1) substrates in very high yields [14][15][16]. In the case of catalyst-free growth, ordered arrays of nanowires can in principle be attained by employing a patterned SiO 2 mask [15,[17][18][19].…”