Crystalline (Al1-xBx)PSi3 and (Al1-xBx)AsSi3 tetrahedral phases via reactions of Al(BH4)3 and M(SiH3)3 (M = P, As)

Patrick Sims, Toshihiro Aoki, Ruben Favaro, Patrick Wallace, Andrew White, Chi Xu, Jose Menendez, John Kouvetakis

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Abstract

Crystalline Al1-xBxPSi3 alloys (x = 0.04-0.06) are grown lattice-matched on Si(100) substrates by reactions of P(SiH3)3 and Al(BH4)3 using low pressure CVD. The materials have been characterized for structure, composition, phase purity, and optical response by spectroscopic ellipsometry, high-resolution X-ray diffraction, high-resolution transmission electron microscopy, electron energy loss spectroscopy, and energy dispersive spectroscopy, which indicate the formation of single phase monocrystalline layers with tetrahedral structures based on AlPSi3 parent phase. The latter comprises interlinked AlPSi3 tetrahedra forming a cubic lattice in which the Al-P pairs are imbedded within a diamond-structured Si matrix as isolated units. Raman scattering of the Al1-xBxPSi3 films supports the presence of substitutional B in place of Al and provides strong evidence that the boron is bonded to P in the form of isolated pairs, as expected on the basis of the AlPSi3 prototype. The substitution of small size B atoms is facilitated by the stabilizing effect of the parent lattice, and it is highly desirable for promoting full lattice matching with Si as required for Si-based solar cell designs. The substitution of B also increases the bond-length disorder leading to a significantly enhanced absorption relative to crystalline Si and AlPSi3 at E < 3.3 eV which may be beneficial for PV applications. Analogous reactions of As(SiH3)3 with Al(BH4)3 produce Al1-xBxAsSi3 crystals in which the B incorporation is limited to doping concentrations at 1020 atoms/cm3. In both cases the classical Al(BH4)3 acts as an efficient delivery source of elemental Al to create crystalline group IV-III-V hybrid materials comprising light, earth abundant elements with possible application in the fields of Si-based technologies and light-element refractory solids.

Original languageEnglish (US)
Pages (from-to)3030-3039
Number of pages10
JournalChemistry of Materials
Volume27
Issue number8
DOIs
StatePublished - Apr 28 2015

ASJC Scopus subject areas

  • Chemistry(all)
  • Chemical Engineering(all)
  • Materials Chemistry

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