Surface morphology, microstructure and electrical properties of Ca-doped ZnO thin films

In the present work, a Ca-doped zinc oxide nanoparticle (ZOCa NPs) were synthesized using modified sol-gel process. X-ray diffraction study exhibited a highly crystalline ZOCa NPs with hexagonal Wurtzite structure. ZOCa samples were deposited by pulsed laser deposition (PLD) process to obtain ZOCa/p-Si heterojunction. The structural properties of this heterojunction were analyzed using X-ray diffraction. Electric and dielectric parameters of the heterostructure were studied after the deposition of gold contacts on the two parallel faces. The obtained Au/ZOCa/p-Si/Au heterojunction was studied by impedance spectroscopy system. The measured capacitance and conductance have a strong dependence on frequency (f) and voltage in the depletion and accumulation regions because of the presence of interface states (IS) and polarization processes predominantly at low f. The dielectric constant (epsilon ') values increase with decreasing f. We found that Ca doping had a strong effect on the performance of the device, and the ZOCa/p-Si heterojunction formed by ZOCa NPs is promising for rectifying electronic properties.