Fig. 4: Quantitative measurement of the built-in ferroelectric field.
From: Highly tunable band structure in ferroelectric R-stacked bilayer WSe2
a Reflectance map at a fixed electron density of n = 2.0 × 1012 cm−2 as a function of displacement field, showing the evolution of attractive polaron energies. b Schematic illustrating how the external field tunes the electron distribution between layers. c Peak energies of the attractive polarons (\({{\rm{{AP}}}}_{{\rm{{L}}}}^{-}\), \({{\rm{{AP}}}}_{{\rm{{H}}}}^{-}\)) and their energy difference (ΔE) versus displacement field with different doping levels. The built-in field is identified at D ≈ 0.102 V/nm, where the polaron energy splitting matches that of the neutral excitons (indicated with a dashed black line). The error bars represent the standard errors of the fitted peak center positions.
