Laser oxidation and wide-band photoluminescence of thermal evaporated bismuth thin films

Abstract

Bismuth (Bi) thin films of various microstructures were synthesized by thermal evaporation at varying substrate temperatures. The substrate temperature strongly affects the surface morphology and crystalline orientation of the Bi thin films. Peak shift and broadening of the Raman bands (Eg and A1g modes) observed with an increase in substrate temperature can be attributed to the phonon confinement and compressive stress effects. The Bi thin film depicts a laser-induced oxidation and phase transition as a function of varying laser power. Photoluminescence spectra show visible–near infrared broadband emission for polycrystalline Bi thin film prepared at high substrate temperature. This result indicates that polycrystalline Bi thin film can be a promising candidate for broadband optical fibre amplifiers and tunable lasers.

A note on the characterization of bismuth black by Raman microspectroscopy

“…Bismuth is subject to thermal oxidation, [9] which, as explored in the work presented here, may be induced by laser heating during Raman spectroscopy if excessive laser powers are used. Nonetheless, Raman spectroscopy has been employed in recent studies of bismuth nanoparticles, [10 -12] clusters [13] and thin films [14] where the fundamental Raman modes, [15] E g and A 1g , were monitored to study changes in structural properties such as particle size and crystallinity. Raman spectroscopy also has been used to characterize bismuth oxide powders and single-crystals, [16 -18] and, more recently, bismuth oxide nanostructures [19,20] and thin films.…”

Potential of bismuth nanoparticles embedded in a glass matrix for spectral-selective thermo-optical devices

“…23 It is noteworthy to point out that no Raman band associated to the presence of bismuth oxides was observed. 27 The dielectric function (refractive index (n) and extinction coefficient (k)) for both the as-prepared Bi-doped glass and the Bi NPs:glass are shown in Fig. 1(b).…”

Optical band gap tuning by laser induced Bi diffusion into As2Se3film probed by spectroscopic techniques

“…The new band at 84 cm À1 can be attributed to asymmetric stretching modes of the Bi-Bi chain in the amorphous matrix. 58 The peak at 137 cm À1 for As 2 Se 3 shis to 119 cm À1 due to Bi deposition and lower still (109 cm À1 ) due to diffusion of Bi into As 2 Se 3 . With deconvolution, as-prepared Bi/As 2 Se 3 has a peak at 138 cm À1 that corresponds to the As-As homopolar bonds with an increase in area under the peak compared to the As 2 Se 3 lm (125 cm À1 ) as shown in Fig.…”