Determination of the substitutional nitrogen content and the electron effective mass in InN/sub x/Sb/sub 1-x/ [001] epitaxial layers

The electronic properties of epitaxial layers of InN/sub x/Sb/sub 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/sub 0.02/Sb/sub 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/sub 0.0015/Sb/sub 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.