Mo‐Induced Crystallization Control in Si/CuO Heterojunctions Enabling Tunable Electronic Transport and High‐Performance Circular Microcavity Antennas

ABSTRACT Herein, robust crystallization of thermally evaporated CuO on Si is achieved through the application of Mo‐nanosheets, with a 20‐nm coating being sufficient to induce monoclinic CuO formation and further increases in Mo thickness producing no measurable change in structural order. Mo‐induced tuning of band bending and depletion width in SCM‐xx devices is demonstrated at 1 MHz. The capacitance‐voltage and Mott–Schottky analyses reveal a non‐monotonic capacitance response with strong suppression in SCM‐20. In addition, the current‐voltage characteristics show increasing voltage‐dependent asymmetry with Mo nanosheet thickness. Moreover, an engineered capacitively loaded circular microcavity antenna (CL‐CMA) based on a vertically integrated Ag/Si/CuO/Mo/Ag heterostructure exhibits excellent resonance at 2.6, 3.07, and 3.20 GHz as a result of the Mo coating on CuO, with return loss exceeding 40 dB at 3.20 GHz and a bandwidth of 2.25 GHz, values that are promising for high‐frequency applications. Furthermore, full‐wave electromagnetic simulations examining how Mo thickness influences the RF behavior of Si/CuO structures contacted by Ag electrodes, reveal that a 20‐nm Mo layer provides the most efficient impedance matching and deepest S 11 minimum. The radiation patterns remain largely unchanged across samples. Overall, the features of the devices are promising for advanced electronic applications.