Heat transport in nano materials subject to high intensity nano focused X-rays

Abstract: The thesis aims to investigate the amount and distribution of heat in nano materials irradiated by highly focused X-ray beams, like those that will be produced by MAX IV. The beam used in the study had a flux of 10e11 photons per second and a diameter of 100 nm. The materials studied were a 2 µm long and 100 nm wide Indium phosphide (InP) nanowire on a Silicon nitride (Si3N4) substrate, a similar 3 µm long nanowire with gold contacts and a gold drop on a silicon substrate. COMSOL, utilising the Finite element method (FEM), was used to calculate the temperatures. The temperatures of the sample varied between 20 C and 25 C in most cases, except for high photon fluxes when it reached 90 C. The room temperature was set to 20 C. The materials reached steady state in the order of a few to a few tens of nanoseconds. The conductance of heat between the sample and the substrate was found to be the most significant factor affecting the maximum temperature reached by the sample. Radiative heat loss does not seem to be significant for the conditions studied.