Determination of the substitutional nitrogen content and the electron effective mass in InNxSb1-x [001] epitaxial layers

The electronic properties of epitaxial layers of InN_xSb_1-x grown on GaAs [001] substrates have been investigated using high-resolution electron-energy-loss spectroscopy (HREELS), Hall measurements and band structure modelled by a modified k·p Hamiltonian. The chemical composition of the epitaxial layers was found to be InN_0.02Sb_0.98 from secondary ion mass spectrometry (SIMS). However, electrical measurements and band structure calculations indicate a band gap of 135 meV, thus entailing an epilayer composition of InN_0.0015Sb_0.9985, indicating that approximately 7.5% of the nitrogen present is electrically active, being located substitutionally on antimony lattice sites. Hall measurements and simulations of HREEL spectra imply a much larger effective mass at the Fermi level than a conventional Kane band structure material with an equivalent band gap.