Frequency-Selective Surface Coupled Metal-Oxide-Metal Diodes

Metal-Oxide-Metal diodes offer the possibility of directly rectifying infrared radiation. To be effective for sensing or energy harvesting they must be coupled to an antenna which produces intense fields at the diode. While antennas significantly increase the effective capture area of the MOM diode, it is still limited and maximizing the captured energy is still a challenging goal. In this work we investigate integrating MOM diodes with a slot antenna Frequency Selective Surface (FSS). This maximizes the electromagnetic capture area while minimizing the transmission line length which helps reduce losses because metal losses are much lower at DC than at infrared frequencies. Our design takes advantage of a single self-aligned patterning step using shadow evaporation. The structure is optimized at 10.6 mu m to have less than 2% reflection (polarization sensitive) and simulations predict that 70% of the incident energy is dissipated into the oxide layer. Initial experimental results fabricated with e-beam lithography are presented and the diode coupled FSS is shown to produce a polarization sensitive unbiased DC short circuit current. This work is promising for both infrared sensing and imaging as well as direct conversion of thermal energy.