Boron phosphide films prepared by co-evaporation technique: Synthesis and characterization

We report the physical and electronic properties of BP films of 1:1, 1:1.15 and 1.25:1 stoichiometry prepared by co-evaporating B and P onto glass and Si (100) substrates. Compositional information was obtained from X-ray photoelectron spectroscopy measurements. Optical studies indicated allowed indirect transition at ∼ 2.08 eV. The room temperature photoluminescence peak at ∼ 2.01 eV was due to band gap transitions which shifted to higher energy value when recorded at lower temperature. Fourier transformed infrared (FTIR) spectra were dominated by the characteristic peak of the B–P located at ∼ 810 cm− 1 which could be identified as arising due to transverse optical vibration mode (k ∼ 0) while the shoulder at ∼ 850 cm− 1 may be due to longitudinal optical (k ∼ 0) vibration mode. Other characteristic peaks for B–O, P–O and B–H vibration modes were also present in the FTIR spectra. Characteristic Raman peaks for BP located at ∼ 415 cm− 1 and 806 cm− 1 were observed in these films.