Fig. 4: VSe2-thickness-dependent electronic modulation of insulating bulk states in Bi2Se3.
a 2D plots of the transient reflectance (TR) spectra of VSe2/Bi2Se3 heterostructures (VBHs). The dashed horizontal lines indicate the optical transition energy (Eopt) of 10 quintuple layer (QL) Bi2Se3 (red) and VBHs (black), respectively. b Selected TR spectral features at 25 ps with fitting curves based on Eq. (4) and (c) corresponding absorption changes (Δ\(\alpha\)). The nex and Γ represent the photoexcited carrier concentration and broadening factor of photoinduced absorption changes, respectively. d VSe2-thickness-dependent Eopt obtained by fitting from (b). The line fit delivers a slope of 0.26 meV nm−1. e VSe2-thickness-dependent Γ of the optical transition estimated by model fitting based on Eq. (4). f Dynamic evolution of TR signals in Bi2Se3 and VBHs. The gray fit curves indicate biexponential decays in Bi2Se3 and VBHs with 48 nm and 118 nm VBH. Inset: VSe2-thickness-dependent interband recombination time of metastable carrier in Bi2Se3 (τ2). The error bars in (d), (e), and the inset of (f) indicate the standard error of the fitted values in (b).
