Correlation between microstructural and optoelectronic properties of porous Si/SnO2 composites coated Al2O3

In this work, Al2O3 coating effect on morphology, structure and optoelectronic properties of Si/SnO2/Al2O3 porous matrix composites (PMCs) were investigated. A three-staked thin layers deposited on a < 100 > oriented silicon substrate made these composites. First, porous silicon layers were achieved by electrochemical etching method. Then Al2O3 and SnO2 layers were successively deposited by physical and chemical vapor deposition, respectively. Morphological and microstructural properties of the as prepared composites were evaluated by Scanning electron microscope, energy dispersive X-ray spectroscopy and X-ray diffraction. Results proved that Al2O3 concentration alters notably the porosity of the PMCs.Variable angle spectroscopic ellipsometry (SE) revealed a high correlation between the optical constants (n, k) and the PMC microstructure. Impedance spectroscopy revealed a semiconductor-metallic transition at high frequency in the temperature range between 340 and 410 degrees C.

Automated summary

This work investigates the effect of Al2O3 coating on the morphology, structure, and optoelectronic properties of Si/SnO2/Al2O3 porous matrix composites. The results show that the Al2O3 concentration significantly affects the porosity of the composites. Variable angle spectroscopic ellipsometry reveals a high correlation between the optical constants and the microstructure of the composites. Impedance spectroscopy demonstrates a semiconductor-metallic transition at high frequency.