Fig. 1: Anisotropic characterization of Te nanoflake.
From: Stable mid-infrared polarization imaging based on quasi-2D tellurium at room temperature
a Schematic of the crystal structure of Te with a helical chain formed by three adjacent tellurium atoms. b Schematic of the device structure. c Optical image of the device, the distance between the five electrodes are 4, 3, 2, and 1 μm, respectively. d Transfer curve at different channel lengths, the selected electrodes are marked in the legends, the drain bias is 1.0 V. e Anisotropic transfer curve along x- and y-axis, the gate bias is from −10.0 to 10.0 V, the drain bias is fixed at 1.0 V. The inset shows the drain current under the drain bias from −1.0 to 1.0 V and the gate bias of 0 V, the current along x-axis is ∼2.24 times of the current along y-axis. f Calculated on–off ratio and field-effect mobility based on the transfer curve in (e) along x- and y-axis. g Anisotropic ratio of on/off ratio and mobility based on the data in (e). h Polarized Raman intensity mapping of tellurium nanoflake as a function of wave number and incident angle, i–k polar plot of E1-TO, A1, and E2 mode intensity. E1-TO, A1 mode are two-lobe shape, and E2 mode is four-lobe shape. The red spots are experimental results, and the blue dashed lines are fitted results. The anisotropic ratios are ∼13, ∼4, and ∼12.5 for E1-TO, A1, and E2 mode, respectively. l Absorption spectra of tellurium nanoflake, the red line is the unpolarized absorption spectra of tellurium nanoflake, with a peak located at ∼1.25 μm, and the green and blue lines are polarized absorption spectra of Te nanoflake, with the incident light polarization direction along x- and y-axis, respectively. From 1.25 to 3.0 μm, the absorption along x-axis is higher than that along y-axis, and the anisotropic ratio at 1.25 and 2.3 μm are ∼1.8 and ∼8.0, respectively.
