Characterization of Silver Microheaters for Vertical- Cavity Enhanced Resonant Thermal Emission

We designed, simulated and experimentally characterized thin silver microheater structures placed on a dielectric multilayer membrane, which represent the concept of vertical-cavity enhanced resonant thermal emission (VERTE). This concept has the goal to achieve selective and coherent thermal emission on the backside of the multilayer membrane. The dielectric stack also is responsible for the thermal insulation, i.e. is preventing heat to be conducted away into the silicon substrate. However, the large fractions of silver demanded by the VERTE concept seem to contradict the goal of high thermal insulation for efficient heating. Here, we focus on microheater structures with high fractions of silver on the area of the membrane. We show that target operation temperatures up to 800 K (suitable for mid IR region) could be reached in finite element simulations and experiments with reasonable amounts of electric power supply, despite conduction losses into the substrate. Sample devices featuring the multilayers were fabricated using PECVD and dry etching. The multilayer membranes showed remarkable mechanical and thermal stability, making the structures suitable for a source for optical on-a-chip mid-infrared sensing.