Near-Infrared Tunable Reflection and Absorption Using Nanostructured Thin Film Structures Employing Phase-Change Material

Abstract

We present the design of a polarization-dependent tunable nanostructured thin film absorber in the nearinfrared region. Germanium antimonide tellurite (GST) was employed as the phase change material in the designed structure. Our structure is composed of a periodic grating-type array of 150 nm thick Au buried with 50 nm thick GST layer from the top of the Au layer. The period of the gratings is 2 µm and in each period, GST width is 1 µm. GST was selected as the active phase change material because its optical properties undergo a substantial change during a structural transition from amorphous to crystalline phase. The optical absorption and reflection properties of the designed structure with respect to the geometric and material parameters were systematically investigated using the finite dierence time domain computations. It was shown that absorption peak or reflection dip at the resonant wavelengths in the near-infrared region was red shifted from 2039 nm to 2143 nm wavelength by switching the phase change material from its amorphous to crystalline states. The distributions of the electric field and absorbed power at the resonant wavelengths with respect to dierent phases of the GST were investigated to further explain the physical origin of the absorption. Our study provides a path toward the realization of tunable infrared absorbers for applications, such as selective infrared emitters, infrared camouflage, sensors, and photovoltaic devices. DOI: 10.12693/APhysPolA.129.464 PACS/topics: 78.67.Pt