Erbium phthalocyanine on porous silicon: Morphological, optical, and electrical characterization, for its possible application as a photodetector

Abstract

Organic semiconductors have recently gained more attention due to their electrical properties and flexibility for combining with other materials, mainly with inorganic semiconductors (silicon). In this work we fabricated heterostructures based on Erbium phthalocyanine (ErPc) on porous silicon (PS) and crystalline silicon (c-Si). The ErPc was synthetized by a solar reaction procedure and deposited on PS and c-Si substrates by sublimation. The PS was obtained by using Metal-Assisted Chemical Etching. We characterized the morphological, optical, and electrical properties of these heterostructures to study their behavior and to propose an optoelectronic application for them. The morphology of the ErPc film resulted in structural differences depending on the substrate; for the case of the silicon substrate, we only found micro-rod structures uniformly distributed and, on porous silicon layers, we obtained a combination of nanoparticles and nanotubes according to the FE-SEM characterization. The diffuse reflectance spectrum of the erbium phthalocyanine showed the lowest reflectance, which is an important parameter for optoelectronic applications to reduce loses from reflectivity. The absorbance spectrum showed the three main bands that identified the presence of the ErPc complex. The heterostructures displayed a rectifying and ohmic behavior in the I–V curves. In addition, a photocurrent effect was observed, but only at high voltages. Finally, the current-time curves obtained from the heterojunctions demonstrated a clear response to white light pulses with 1 V reverse bias. The combination of organic and inorganic semiconductors can open new opportunities for application in optoelectronics.