Structural, optical and electrical properties of Mo-doped CuO thin films and their applications in negative capacitance sources and quad band resonators

Abstract

Herein the effects on Mo- doping on the thermally deposited copper oxide thin films are explored. The X-ray diffraction measurements showed the amorphous nature of the studied films. Thermally evaporated CuO thin films were composed of randomly distributed grains which exhibited grain size reduction upon doping with Mo. The doping agent increased the transmittance and lowered the reflectance in the films. Mo doping also suppressed the free carrier absorption in CuO and widened the energy band gap from 2.45 eV to 2.80 eV upon increasing the doping content from 1.31 at% and 6.23 at%, respectively. In addition, electrical investigations have shown that Mo doping converts the conductivity type from p-type to n-type. The temperature dependent conductivity decreased with increasing Mo content and temperature. Moreover, the conductance and capacitance spectral studies in the microwave frequency domains have shown the domination of negative capacitance effect in the studied samples with decreased negativity with increasing doping content. Mo doping created additional resonance at plasmon frequencies ranging from 1.27 to 1.74 GHz. Assuring the suitability of the doped CuO films for microwave applications.