On-Chip Silicon Thermal Diode: Nanostructure Spacing Dependence of the Thermal Rectification Ratio

We present a silicon-based thermal diode integrated on a chip, capable of direction-dependent heat transport. The device is built upon a thin suspended membrane featuring an asymmetric arrangement of nanometer-scale holes. Integrated nano-heaters and resistance-based temperature sensors enable full electrical control and measurement of the thermal response. Two nanofabrication methods were used for the nanohole patterns: anisotropic chemical etching using potassium hydroxide combined with electron beam patterning, and direct nanostructuring using focused ion beam (FIB). Three-dimensional simulations based on models reconstructed from electron microscopy images were used to interpret the experimental results and to quantify the thermal conductivity and the thermal rectification performance. A rectification ratio of 0.26 was achieved in devices fabricated with the FIB method. These findings demonstrate the potential for implementing nanoscale thermal rectification in scalable silicon platforms compatible with conventional microelectronic technologies, with promising applications in thermal logic, energy conversion, and adaptive thermal management.