Electrical properties comparison of TiO_2/PS/Si devices fabricated by spin coating and electron beam gun

摘要

Three porous silicon (PS) samples with different porosities by electrochemical anodization are fabricated. Then, TiO_2 nanoparticles are deposited on PS by two methods, spin coating and electron beam gun. Ⅰ-Ⅴ characteristics of all samples show diode behavior. Our result showed that transient current decreases with increasing porosity for PS/Si samples while increases for TiO_2/PS/Si samples in both deposition methods. The reason could be due to filling pores by TiO_2 nanoparticles and reduction of resistivity on PS surface. Also, our result showed that transient current increases highly for samples which were deposited by electron beam gun with respect to spin coating. The reason could be that in spin coating method TiO_2 sol with high viscosity was used and causes that TiO_2 nanoparticles cannot easily penetrate into PS pores. But in electron beam gun method TiO_2 nanoparticles reaches to PS surface as a few atoms and can easily penetrate into PS pores. Ideality factor of our samples reduces after TiO_2 deposition. Also, ideality factor of samples which were deposited by electron beam gun decreases with respect to spin coating, since transient current and Ⅰ-Ⅴ curve slop increase in electron beam gun.