Effects of Oxygen Ratio on the Properties of Tin Oxide Thin Films Doped with Bismuth

Abstract

This study examins the effects of the oxygen ratio on the properties of bismuth (Bi)‐doped tin oxide (Bi‐SnOx) films deposited by radio frequency magnetron sputtering using a SnO (90 at%)‐Bi (10 at%) ceramic target. The properties of the samples are characterized by X‐ray photoelectron spectroscopy (XPS), Hall effect measurements, dynamic‐secondary ion mass spectrometry (D‐SIMS), and X‐ray diffraction (XRD). The samples deposited without oxygen gas exhibit Sn4+ and Sn2+ XPS peak areas of 44.7 and 41.1%, respectively. The Sn4+ area increases to 64.1% with increasing oxygen ratio up to 20% with a concomitant decrease of the Sn2+ area to 26%, indicating that SnO2 with n‐type conductivity is the dominant phase under a higher oxygen partial pressure. XPS shows that with increasing oxygen ratio, the chemical state of Bi changes from metallic Bi (Bi0) to Bi3+. Furthermore, with increasing oxygen ratio, the Bi content in the samples increases because of the increase in Bi2O3 formation, which causes a decrease in the number of oxygen vacancies in the samples. These results suggest that the oxygen ratio is useful for controlling Bi doping in SnOx films. Therefore, Bi doping is valuable for suppressing the formation of oxygen vacancies and improving the properties of SnOx films.

Periodic Acid Modification of Chemical‐Bath Deposited SnO2 Electron Transport Layers for Perovskite Solar Cells and Mini Modules

“…For the Sn 3d XPS spectra ( Figure 2 a ), the two peaks of Sn 3d 5/2 and 3d 3/2 in pristine SnO 2 shifted from 487.2 and 495.6 eV to the higher binding energies of 487.6 and 496.1 eV, with the spin–orbit splitting energy of 8.4 eV. [ 18 ] The higher binding energy of Sn 3d indicates more Sn (II)’s conversion to Sn (IV), [ 16 , 19 ] potentially widening the band gap and decreasing the number of oxygen vacancies. [ 20 , 21 ] In terms of O 1s spectra (Figure 2b ), two peaks of around 532.5 and 531.1 eV refer to the hydroxyl group (–OH) on the SnO 2 surface and the saturated lattice oxygen in SnO 2 film, respectively.…”

Enabling a rapid SnO2 chemical bath deposition process for perovskite solar cells

“…† No deconvolution was needed for the CBD samples (15-SnO 2 , 30-SnO 2 , 45-SnO 2 ). All of the peaks have binding energies close to 486.6 eV, 25 likely suggesting the full conversion of Sn 2+ from the precursor into Sn 4+ . To conrm this, XPS of commercial SnO 2 powder was also performed, which showed similar peak energies (Fig.…”

“…Instead, only enough was etched to ensure that region is non-conductive. Fortunately, these peaks have binding energies closer to Sn 2+ (486 eV) 25 rather than Sn 4+ , so the fact that the coated samples seem to comprise only Sn 4+ shows that Sn 3d contributions from the uncoated glass are likely to be negligible, despite the lack of 100% SnO 2 coverage on all sonicated lms (as shown in Fig. 2b).…”

Experimental Investigation and DFT Study of Tin-Oxide for Its Application as Light Absorber Layer in Optoelectronic Devices

“…Band gap of SnO films for its different tin and oxygen ratio have been extracted by Tauc plot as shown in the figure 6 (b). From figure , it is observed that band gap increases with an increase in the Sn:O ratio, which is mainly due to the fact that with an increase in oxygen ratio of SnO film, its properties highly tends to toward the SnO 2 (Tin-dioxide) nature [12], [22], [23]. We extended the experimental study further to investigate the electrical parameters of SnO films for its different composition of Sn and O ratios using Hall measurement in order to find out nature of SnO films, its carrier concentration, Hall mobility and sheet resistivity using equations given below.…”