Gold plasmonic material for enhanced Hg1–xCdxTe infrared absorption

Abstract

There are potential applications for high operating temperature (HOT) Hg1-xCdxTe (MCT) infrared (IR) devices for both defense and commercial applications. MCT absorption can be raised either by increasing the absorber thickness or by lowering the operating temperature. However, if we can increase MCT absorption by using plasmonic materials, it will help in both HOT operation and increasing signal to noise ratio. We studied three Gold (Au) plasmonic structures for the absorption enhancement of MCT materials in the wavelength band of 3-7 μm. By using RF module in COMSOL multiphysics software, we found a large increase (1.85X) of MCT absorption when the optimized Au plasmonic structure is used. The increase in absorption at 4.5-6 μm is higher than that at 3-4 μm. The increased absorption due to plasmonic structure allows absorber thickness to decrease which leads to decrease in dark current and HOT devices. We report here record 90% increase in absorption of MCT material at room temperature at peak wavelength around 3.4 μm by using optimized plasmonic structure.