Investigating the opto-electronic and photovoltaic properties of Zn-incorporated CuO thin film grown by vapor–liquid–solid (VLS) method

In the current study, Zn-incorporated CuO (CuO:Zn) and pure CuO thin film heterojunction devices have been fabricated on n-Si ( \(\langle 100\rangle\) $⟨100⟩$ ) substrate, applying vapor–liquid–solid (VLS), for their potential application as photovoltaic devices. The uniformity of the thin films on Si-substrate and their crystalline orientation are verified using FESEM images and XRD studies, respectively. EDS and XPS measurements analyze the chemical stoichiometry and valance states of the as-grown oxides. The influence of incorporating Zn atoms on the structural stabilities of Zn-incorporated CuO was further studied using the DFT (density functional theory) simulation. From spectroscopic ellipsometry measurement, the direct energy bandgaps of CuO:Zn and CuO thin films are assessed to be 2.26 eV and 2.05 eV, respectively. Further, the electronic properties of such heterojunctions are investigated from the junction current–voltage and capacitance–voltage characteristics. The comparative photovoltaic study of CuO:Zn and CuO films suggests that the introduction of Zn into the CuO matrix enhances the power conservation efficiency (PCE %) and external quantum efficiency (EQE%) by almost 2 times. Also, a high spectral responsivity (~ 0.30 A/W @ 0 V) as well as detectivity (1.96 × 10¹² cm Hz^1/2/W @ 0 V) have been achieved for the CuO:Zn/n-Si photodetector. Therefore, the incorporation of ZnO into the CuO lattices by employing the cost-effective VLS mechanism suggests a significant improvement of optoelectronic and photovoltaic properties of such films for the fabrication of future devices.