Enhancement in optoelectronic properties of lanthanum co-doped CdO: Zn thin films for TCO applications

This work reports on structural, electrical, optical, and photosensing properties of La and Zn co-doped CdO thin films. The co-doped CdO thin films were prepared on glass substrates using the nebulizer spray method at 350 C. From the structural analysis, a decrease in the crystallite size from 20 to 16 nm is observed against the incorporation of La in CdO:Zn. Inclusion of La in CdO:Zn has also changed the surface morphology with a reduction in the roughness of the thin film samples. EDX analysis confirmed the incorporation of La with CdO: Zn in the prepared films. The bandgap value of the prepared samples increased with the increase in La concentration. A 1.5 wt % of La co-doped with CdO:Zn thin film sample produces low resistivity of 6.81 x 10(-4) omega cm and a better figure of merit of 8.4 x 10(-4) omega(-1). Finally, the fabricated photodetector with 1.5 wt% of La co-doped with CdO:Zn thin film shows a higher photocurrent and an ideality factor value of 3.4. The photosensing properties of the fabricated (p-Si/CdO-Zn-La (1.5%)) photodetector shows a higher responsivity (R) value of 1.18 AW(-1), specific detectivity (D*) value of 4.90 x 10(9) Jones, and external quantum efficiency (EQE) value of 274% with 3.0 mW/cm(2) light intensity. The switching characteristics of the photodetector show a faster rise time (2.9s) and fall time (3.6s) suggesting the fabricated device suitable for photosensing applications.

Automated summary

This work reports on the structural, electrical, optical, and photosensing properties of La and Zn co-doped CdO thin films. The incorporation of La in CdO:Zn reduces the crystallite size and changes the surface morphology of the thin film samples. The co-doped thin film with 1.5 wt% of La shows low resistivity and a better figure of merit. It also exhibits higher photocurrent and ideality factor values, as well as improved photosensing properties.