Thermal Radiation From Modulated Metal Surfaces

Official URL: https://risc01.sabanciuniv.edu/record=b3205721

In this thesis we developed techniques to fabricate various periodically or quasi periodically corrugated graphene and metal films on PDMS. Period of the films could be repetitively modulated by mechanically induced strain. We analyzed the emissivity of the surfaces in infrared range and the effect of mechanical strain towards developing emissivity control mechanisms. Such surfaces are expected to create enhancement or diminution in the emissivity at wavelengths related to the corrugation periodicity. We applied multiple approaches to create modulable thin films. A soft fluoropolymer (CFx) skin layer with controllable thickness was deposited on PDMS by CHF3 plasma gas. Pitch sizes were controlled by varying the tensile strain of the PDMS substrate and RIE treatment time. However, graphene did not transfer on CFx with full surface coverage. A uniform 3D modulation of graphene on PDMS was achieved via mold fabricated by lithography and directional wet etching. Multilayer graphene films were synthesized on a patterned nickel film using chemical vapor deposition and transferred on to PDMS while maintaining the structural integrity of graphene. Consequently, a crack-free uniform multilayer graphene on PDMS with controlled periodicity such as the wavelength, orientation, and spatial location has been achieved. Ni stripes on SiO2 deposited lift off with various periodicity and aspect ratio showed modulation in IR emissivity. Using another technique spontaneously corrugated Ni thin film on top of PDMS with different periodicity were also synthesized. These patterned metal surfaces exhibited tunable emissivity in the IR wavelengths correlated with the corrugation periodicity of the films.