Nanosynthesis routes to new tetrahedral crystalline solids: Silicon-like Si₃AlP

We introduce a synthetic strategy to access functional semiconductors with general formula A₃XY (A = IV, X-Y = III-V) representing a new class within the long-sought family of group IV/III-V hybrid compounds. The method is based on molecular precursors that combine purposely designed polar/nonpolar bonding at the nanoscale, potentially allowing precise engineering of structural and optical properties, including lattice dimensions and band structure. In this Article, we demonstrate the feasibility of the proposed strategy by growing a new monocrystalline AlPSi₃ phase on Si substrates via tailored interactions of P(SiH₃)₃ and Al atoms using gas source (GS) MBE. In this case, the high affinity of Al for the P ligands leads to Si₃AlP bonding arrangements, which then confer their structure and composition to form the corresponding Si₃AlP target solid via complete elimination of H₂ at ∼500 °C. First principle simulations at the molecular and solid-state level confirm that the Si ₃AlP building blocks can readily interlink with minimal distortion to produce diamond-like structures in which the P atoms are arranged on a common sublattice as third-nearest neighbors in a manner that excludes the formation of unfavorable Al-Al bonds. High-resolution XRD, XTEM, and RBS indicate that all films grown on Si(100) are tetragonally strained and fully coherent with the substrate and possess near-cubic symmetry. The Raman spectra are consistent with a growth mechanism that proceeds via full incorporation of preformed Si ₃AlP tetrahedra with residual orientational disorder. Collectively, the characterization data show that the structuro-chemical compatibility between the epilayer and substrate leads to flawless integration, as expected for pseudohomoepitaxy of an Si-like material grown on a bulk Si platform.