III–V Integration on Si(100): Vertical Nanospades

Abstract

III–V integration on Si(100) is a challenge: controlled vertical vapor liquid solid nanowire growth on this platform has not been reported so far. Here we demonstrate an atypical GaAs vertical nanostructure on Si(100), coined nanospade, obtained by a nonconventional droplet catalyst pinning. The Ga droplet is positioned at the tip of an ultrathin Si pillar with a radial oxide envelope. The pinning at the Si/oxide interface allows the engineering of the contact angle beyond the Young–Dupré equation and the growth of vertical nanospades. Nanospades exhibit a virtually defect-free bicrystalline nature. Our growth model explains how a pentagonal twinning event at the initial stages of growth provokes the formation of the nanospade. The optical properties of the nanospades are consistent with the high crystal purity, making these structures viable for use in integration of optoelectronics on the Si(100) platform.

Semiconductor nanowires: to grow or not to grow?

“…To give an example, silicon nanowires could be first etched on a substrate. These could be used as templates to initiate growth of III-V nanowires on their tips and create an axial heterostructure [52,275,276]. Likewise, etched III-V nanowire structures could benefit from passivation with a subsequent radial growth of a higher bandgap material.…”

GaAs nanoscale membranes: prospects for seamless integration of III–Vs on silicon

“…61 In the presence of an APB, the growth front evolves along different angles on both sides of the boundary, which explains the formation of kinks at the surface of the nanostructure. The presence of complex APBs at the merging point between polar crystals has been also observed in complex nanostructures such as V-shape nanofins, 61 vertical nanospades 62 and close to the nucleation seed of A-polar GaAs NWs. 63 In addition, the complex defects appearing in this region also accumulate strain around them (medium-angle annular dark-field (MAADF) images revealing the accumulation of strain are shown in the ESI †).…”

“…This is due to the change of polarity in the horizontal direction and is quite similar to what is observed in vertical nanospades. 62 The presence of this highly defective structure at the base of NM B is in stark contrast to the relatively defect-free region observed in NM A. The existence of these two very different crystal structures in NMs grown side-by-side underline the importance of controlling the phase and coalescence of nucleated islands to achieve defect-free crystal growth of III-Vs on Si.…”

Selective Area Epitaxy of GaAs/Ge/Si Nanomembranes: A Morphological Study

“…Heteroepitaxial growth could be an effective method for III-V/Si integrated device fabrication, although several issues remain unsolved [4][5][6]. First, the zincblende lower symmetry of GaAs compared to the diamond one of Si (or Ge) returns the formation of antiphase domains (APD).…”

“…A careful optimization of the growth parameters [13], i.e., temperature, deposition flux, and III/V ratio, is required to exclude spurious growth on the masked regions in order to achieve perfect selectivity. Several examples of homoepitaxial growth by SAE have been reported in the literature for III-V nanostructures, such as quantum dots, nanowires, and nanomembranes [6,11,[14][15][16][17].…”