Fig. 2From: Electrically tunable metasurface perfect absorber for infrared frequenciesIllustration of carrier movement inside ITO under voltage bias. Free electrons in the ITO layer accumulate near the interface of ITO and Al2O3. Accumulated carrier concentration decreases exponentially as distance from the interface increases. Direction x represents a reference coordinate to describe carrier density along to the depth of the ITO layer in Fig. 3 Back to article page