title: Ultrafast hole carrier relaxation dynamics in p-type CuO nanowires.
abstract: Ultrafast hole carrier relaxation dynamics in CuO nanowires have been investigated using transient absorption spectroscopy. Following femtosecond pulse excitation in a non-collinear pump-probe configuration, a combination of non-degenerate transmission and reflection measurements reveal initial ultrafast state filling dynamics independent of the probing photon energy. This behavior is attributed to the occupation of states by photo-generated carriers in the intrinsic hole region of the p-type CuO nanowires located near the top of the valence band. Intensity measurements indicate an upper fluence threshold of 40 μJ/cm2 where carrier relaxation is mainly governed by the hole dynamics. The fast relaxation of the photo-generated carriers was determined to follow a double exponential decay with time constants of 0.4 ps and 2.1 ps. Furthermore, time-correlated single photon counting measurements provide evidence of three exponential relaxation channels on the nanosecond timescale.
authors.affiliation: Research Center of Ultrafast Science, Department of Physics, University of Cyprus, PO Box 20537, Nicosia, 1678, Cyprus. othonos@ucy.ac.cy.
authors.forename: Andreas
authors.initials: A
authors.lastname: Othonos
authors.forename: Matthew
authors.initials: M
authors.lastname: Zervos