Ultrafast Carrier Dynamics of Undoped and Ho³⁺-Doped α-Bismuth Oxide Microrods

Abstract

We report the femtosecond two-color pump–probe studies on bismuth oxide microrods. The undoped data show three distinct decays: (1) fastest decay (τ1 ∼ 0.3–0.5 ps) attributed to intraband nonlinear effects (2) intermediate two-body decay (τ2 ∼ 3 ps) attributed to the trap-assisted Auger recombination; and (3) slow single-body decay (τ3 ∼ 36 ps) attributed to the Shockley–Read–Hall recombination. Upon doping with Ho3+, the sample shows an additional slow decay (τ4 ∼ 12 μs), attributed to the Shockley–Read–Hall recombination due to the trap states formed by the doping, along with the three decays observed in the undoped sample. The imaginary parts of third-order susceptibility values for both doped and undoped samples were estimated from the pump–probe studies, and the values are found to decrease inversely with pump fluence suggesting the plausible contribution from hot electrons.

Raman spectroscopic and magnetic properties of Europium doped nickel oxide nanoparticles prepared by microwave-assisted hydrothermal method

“…The (I2LO/I1LO) ratio was found to be 0.86 and 0.43 for NiO and Ni0.95E0.5O, respectively. The ease off in the coupling strength of Ni0.95E0.5O samples in comparison with pure NiO can be due to the reduction in phonon lifetime that arises due to the defects on the surface [52,53]. This observation is in accordance with the results obtained from XPS analysis.…”

“…were observed in the Raman spectra, the intensity ratio of 1LO to 2LO (I2LO/I1LO) can be found to estimate the coupling strength [32,53,63]. The (I2LO/I1LO) ratio was found to be 0.86 and 0.43 for NiO and Ni0.95E0.5O, respectively.…”

“…Moreover, Raman spectroscopy can be successfully utilized to probe the doping effect and local vibrational modes, electro-phonon coupling, spin-phonon coupling, etc. [51][52][53]. Figure 6 shows the recorded room temperature Raman spectra of the prepared pure NiO and Ni0.95E0.5O nanostructures within the range from 250 to 1300 cm -1 .…”

Double Insurance of Continuous Band Structure and N–C Layer Induced Prolonging of Carrier Lifetime to Enhance the Long-Wavelength Visible-Light Catalytic Activity of N-Doped In2O3

“…The best fitting results (Table S4) show that the both kinetics present the similar decay trend (τ 2 and τ 4 ) for commercial In 2 O 3 and N–In 2 O 3 . However, an additional fast decay τ 1 (6.5 ps) is shown after N-doping, and it should be attributed from the doping-assisted trapping process. , It was reported that the electron-trapping process in semiconductors usually has a picosecond lifetime . Therefore, the 54 and 64 ps in both kinetics come from the electron trapping by shallow defect sites near conducting band.…”

“…However, an additional fast decay τ 1 (6.5 ps) is shown after N-doping, and it should be attributed from the doping-assisted trapping process. 90,91 It was reported that the electron-trapping process in semiconductors usually has a picosecond lifetime. 92 Therefore, the •− was an important active…”