Fig. 1: Device structure and measurement scheme.
From: Imaging multilevel exciton transport enabled by correlated electronic states
a Schematic of an optical imaging technique integrating femtosecond transient absorption microscopy with an exciton sensor for ultrafast exciton dynamics (Methods). b Optical image of the fabricated device. The dot indicates the position of the pump–probe measurement spot. c Lateral friction force map of twisted WS2 bilayers with an interlayer twist angle of 58°, resulting in a 9.2 nm moiré pattern. The moiré pattern becomes negligible when isolated by an hBN spacer (inset). d Two-dimensional exciton transport images at a gate voltage Vg = 0. e Exciton population profiles as a function of pump-probe distance x, fitted via a Gaussian function. f Relationship between the mean squared displacement \(\Delta {\sigma }^{2}(t)\) and time, allowing the extraction of \(D\) through the relation \(\Delta {\sigma }^{2}(t)=4{Dt}\). The error bar denotes the standard deviation across the three Gaussian-fit results.
