Composition Effects on Ultrafast Optical Properties of Cu_xO_yThin Films: A Transient Absorption Study

Abstract

Cu 2 O, CuO, and mixed-phase Cu 2 O/CuO thin films with different relative compositions were prepared by oxidizing Cu films at temperatures 150−380 °C for a time period ranging from 2 to 24 h, and their ultrafast transient absorption spectra have been characterized to understand the carrier dynamics of the heterostructured Cu 2 O/CuO system. The absorption dynamics of a pure p-type Cu 2 O sample followed a biexponential decay, with a fast time ∼0.3 ps and a long life >150 ps, while a pure p-type CuO sample showed triexponential decay dynamics, with three time constants, 0.25, 2.5, and >150 ps. For the mixed-phased Cu 2 O/CuO thin films, their absorption dynamics all followed the triexponential decay, and the two ultrafast time constants showed strong composition dependence. Possible energy band structures and electron transition processes are proposed to understand both the spectroscopic and dynamics behaviors of these samples.

Unveiling charge dynamics of visible light absorbing oxysulfide for efficient overall water splitting

“…Since TDR analysis reveals that the Y 2 Ti 2 O 5 S 2 photocatalyst exhibits strong signature of bimolecular recombination and trapping of photogenerated charge carriers with no evidence of Shockley-Read-Hall and auger recombination, the effective bulk carrier lifetime of Y 2 Ti 2 O 5 S 2 is given by as under AM 1.5G operating condition. Using the values obtained from the TDR analysis, we find ns, which is higher than well-known visible-light absorbing metal oxides or nitrides like BiVO 4 50 , 57 , Cu 2 O 58 , -Fe 2 O 3 59 , and Ta 3 N 5 41 . Considering typical value of the effective charge carrier mobility , the diffusion length , which is significantly smaller than the synthesized average radius ( ) of almost of Y 2 Ti 2 O 5 S 2 particles.…”

Ultrafast Carrier Dynamics of Amorphous Zinc Tin Oxide Graded Thin Films

“…A detailed understanding of the carrier dynamics in semiconductor is extremely useful for the development of future optoelectronic systems. Ultrafast optical spectroscopy is a versatile technique to investigate the dynamic process and the corresponding relaxation mechanism of semiconductors. − Despite some effects, however, the carrier dynamics of ZTO are rarely addressed. , Due to the limited experimental data, the intrinsic carrier recombination mechanism following photon absorption in ZTO remains elusive and needs full discernment.…”

BiFeO3 photocathodes for efficient H2O2 production via charge carrier dynamics engineering

“…The third time constant (t 3 ) is attributed to the trapping and recombination of charge carriers. [39][40][41] The final carrier lifetime was calculated by summing up these three-time constants by weights. In comparison, the last carrier lifetime of the composite film is about 4 times that of the bare BFO.…”