Metamaterial perfect absorbers with solid and inverse periodic cross structures for optoelectronic applications

Metamaterial based on a metal/insulator/metal (MIM) tri-layer structure provides an agile platform to realize high absorption efficiency for a variety of applications including semiconductor optoelectronic detectors. In this work, we use the finite time domain difference (FDTD) method and coupled mode theory (CMT) to numerically study metal/semiconductor/metal (MSM) structures and discuss their effective absorption for optoelectronic application. We compare MSM structures with a different top metal layer design and find that cross shaped absorber (CSA) and it's complementary cross shaped absorber (CCSA) exhibit different phase diagrams due to a distinctive dependence of radiation loss on geometrical parameters. Our results show that CSA (CCSA) structures are suitable for thinner (thicker) sandwiched semiconductor with a larger (smaller) imaginary part of its dielectric constant. The necessary condition to realize a maximum figure of merit (FOM) value for effective absorption is discussed in comparison with the perfect absorber condition. Our work may provide guidelines to design the general light-harvesting optoelectronic devices with high efficiencies based on metamaterial-semiconductor hybrid systems.