TiO2/porous silicon heterostructures formation by simple and low-cost methods for electronics applications

In this work, heterostructures of porous silicon (PS) and titanium dioxide (TiO2) were fabricated using low-cost and simple methods to analyze the electrical properties that are usually not studied. The PS was fabricated by metal-assisted chemical etching, and the solvothermal route synthesized the TiO2. The PS showed a sponge-like structure; meanwhile, the TiO2 varied its morphology from nanoparticles, nanosheets, and nanorods; even micro flowers were observed. The electrical characterization in the heterostructures showed a couple of essential effects on electrical characteristics, such as the negative differential resistance (NDR) and oscillations for some heterostructures. These oscillations have been reported in previous investigations. Based on the electrical analysis and the literature, tunneling effects cause the NDR effect, and the oscillation could be due to the charge and discharge effects. It analyzed current-voltage characteristics to find the transport mechanisms. The Fowler-Nordheim tunneling and the space charge limited current determined the predominant mechanism. Also, photocurrent effects were observed in our samples, which confirms that this device can be used as a photodetector. Finally, we calculated some junction parameters from de capacitance-voltage curves. Understanding all these effects and their mechanisms, we can apply these heterostructures in several fields of science and technology areas such as photodetectors, oscillators, Gunn diodes, and transistors. [Display omitted] •Fabrication of TiO2/PS heterostructures.•Low and simple methods for fabrication.•Different morphologies depending on the synthesis condition.•Rectifying and ohmic behavior of the heterostructures.•The simplest relaxation oscillator with these materials.