Photoluminescence of highly porous nanostructured Si-based thin films deposited by pulsed laser ablation

Abstract

Nanostructured, Si-based cottonlike, highly porous thin films of Si, SiNx, and SiOx were deposited by the excimer laser ablation of Si targets in He, He∕N2, and He∕O2 ambients, respectively. Photoluminescence (PL), x-ray photoelectron spectroscopy, and photoacoustic Fourier transform IR have been used to characterize these deposits. After exposure to air, broad PL bands appear at 1.7eV (Si), 2.0eV (SiNx), and 2.3eV (SiOx); air oxidation causes the separation of the PL spectra into two identical component peaks, at 1.5 and 2.3eV, whose relative ratios differ with film composition. The present results indicate that the red PL peak at 1.5eV is due to the localized states at the oxidized surfaces of these materials, while the green PL peak at 2.3eV is due to oxygen-related defects in their local disordered nanostructures.

Laser-Fabricated Fluorescent, Ligand-Free Silicon Nanoparticles: Scale-up, Biosafety, and 3D Live Imaging of Zebrafish under Development

“…XPS analysis of Si-NPs indicated a Si–O bonding surface coverage without other surface contamination. , (Figure S9) FTIR studies confirmed the oxidized surface of Si-NPs with features that are similar to those obtained using different approaches. ,, (Figure D) The main band (1070 cm –1 ) is due to Si–O–Si optical mode covering the particles . Numerous sharp peaks located at 800 cm –1 , 880 and 960 cm –1 corresponding to various SiOx bending mode, nonbridging Si–O bonds, Si–O–Si bonds, and Si–OH bending were observed. Moreover, transitions were seen around 1630, 2260, and in the range 3200–3650 cm –1 , attributed to SiO–H bending, OxSi-H vibrations modes, and the O–H vibrational modes, respectively (Figure S10).…”

“…58,59 (Figure S9) FTIR studies confirmed the oxidized surface of Si-NPs with features that are similar to those obtained using different approaches. 54,60,61 (Figure 4D) The main band (1070 cm −1 ) is due to Si−O−Si optical mode covering the particles. 60 Numerous sharp peaks located at 800 cm −1 , 880 and 960 cm −1 corresponding to various SiOx bending mode, 61 nonbridging Si−O bonds, Si−O−Si bonds, and Si−OH bending 62 were observed.…”

“…54,60,61 (Figure 4D) The main band (1070 cm −1 ) is due to Si−O−Si optical mode covering the particles. 60 Numerous sharp peaks located at 800 cm −1 , 880 and 960 cm −1 corresponding to various SiOx bending mode, 61 nonbridging Si−O bonds, Si−O−Si bonds, and Si−OH bending 62 were observed. Moreover, transitions were seen around 1630, 2260, and in the range 3200−3650 cm −1 , attributed to SiO−H bending, 63 OxSi-H vibrations modes, 64 and the O−H vibrational modes, 65 respectively (Figure S10).…”

Pulsed laser deposited porous nano-carpets of indium tin oxide and their use as charge collectors in core–shell structures for dye sensitized solar cells

“…The absorbed laser light ablates material from the target surface, imparting a large amount of kinetic energy to ejected ions and atoms that then deposit onto a substrate held some distance away to grow a film. Much of the PLD research so far has centred on the deposition of flat crystalline films; however there is a rich variety of recent examples of its use in the deposition of films with complex microstructures [2][3][4][5][6][7][8][9][10][11][12][13][14] created by nano-cluster formation between the target and the substrate due to collisions between the ejected plume and the background gas. 10,[15][16][17] In many instances, the large specific areas of these nanostructured films have given them importance in technological applications such as chemical sensors, [18][19][20][21][22][23][24][25] solid fuel cells, [26][27][28][29][30] and dye sensitized solar cells (DSSCs).…”

Oxidation processes of surface hydrogenated silicon nanocrystallites prepared by pulsed laser ablation and their effects on the photoluminescence wavelength

“…18,32,33 The deposited surface hydrogenated nanocrystal film has a secondary structure composed of nanocrystallites as the primary structure. 34 The nanocrystal film has a porous structure in which the surface area of each nanocrystallite as well as void spaces between the nanocrystallites exist.…”