Structural and electrical characteristics of the ZnO/porous-Si/Si heterostructure: from synthesis to analysis of photocell efficiency

Abstract

The article deals with the step-by-step production of the ZnO/porous-Si/Si heterostructure: electrochemical etching of monocrystalline Si plates (100); deposition of ZnO films by the sol-gel method followed by centrifugation.

A comprehensive study of the morphology of the obtained structure using a scanning electron microscope and an atomic force microscope confirms the high degree of structural order of the obtained film and the presence of the main chemical elements of the ZnO:Al film on its surface. It was established that the thickness of the ZnO:Al film is 395 nm, and the thickness of the porous-Si layer is 90 nm. An atomic force microscope showed that the surface of the material has a complex and heterogeneous structure with pronounced roughness. The maximum height of the profile is ⁓188 nm, indicating significant explosions and protrusions on the surface. The obtained values of the thickness and roughness of the manufactured structure were used to model the ZnO:Al/porous-Si/Si heterostructure in the PC1D program in order to find the optimal parameters of the solar cell. The values of no-load voltage, short-circuit current and maximum power were obtained from the simulation results, the filling factor and efficiency were calculated theoretically. Simulation results show that the fill factor of the fabricated structure is ~70.4%, and the efficiency of the ZnO/porous-Si/Si photoconverter is 22.4%. Increasing the level of doping to 1019 cm-3 leads to an increase in the efficiency of the photocell to a maximum value of 23%.

Keywords: electrochemical etching, sol-gel method, heterostructure photoconverter, simulation