Journal of Applied Sciences and Nanotechnology

Photoelectrochemical etching (PECE) was used to prepare porous silicon (PS) layers of polished surfaces of (100) n-type silicon wafers with a resistance of 0.1-100 μm and thickness of 600 ± 25 μm. The directed slices are to be catalyzed at different etching times (5, 15, 25 min) with a constant Hydrofluoric acid of 20% and with a fixed current density of 20 mA/cm². The porous silicon morphology was investigated using scanning electron microscopy (SEM). Samples were formed by different engraving times. It revealed that the silicon surface has a layer of sponge-like structure, with the average pore diameter (740±1 nm, 550±2 nm,460±3 nm) of the porous silicon increasing as the etching time increased. PS Al PS /Si /Al photodetectors were found to work as a photodetector over a wide wavelength responsivity.

The manufacturing of vacuum sensors is critical to several vacuum-based applications. Porous silicon (PSi) was chosen as the vacuum sensor due to the possibility of moving air particles settled inside the pores while being put in the vacuum. The characteristics of porous silicon sensing to the evacuation of gases during vacuum was inferred by changing in the electrical resistivity. This work depends on the change in the electrical resistance of the PSi layers that was prepared via photo-electrochemical technique on the n-type (100) oriented silicon wafer. The surface topography of porous silicon is necessary to understand the morphological properties. Therefore, structural and morphological characterization of PSi samples were studied and analyzed using the scanning electron microscope (SEM) and X-Ray Diffraction (XRD) pattern. The etching process was carried out with various etching times, hydrofluoric acid (HF) concentration, and constant current density. The results showed that the pore size is increased as the etching time increased. The etching time produced pores of different sizes. The electrical resistance values were calculated after placing the sample in the vacuum system, starting from atmospheric pressure down to torr. The electrical properties of PSi indicate that electrical resistance gradually decreases with increasing vacuum pressure.