Porous silicon passivated with aluminum for photoluminescence enhancement and photodetector applications

The majority of optoelectronic devices based on porous silicon (PS) display low luminescence efficiency and luminous deterioration with age. PS is fabricated by electrochemical etching of p-type Si wafers (100) and passivated with a semi-transparent conducting ultrathin aluminum (Al) layer by auto thermal evaporation technique, with the goal of improving PS photoluminescence (PL) and employing it as a metal-semiconductor-metal (MSM: Au/Al: PS/Au) photodetector. Microstructure and optical characteristics of synthesized samples were analyzed by scanning electron microscopy, diffuse reflectance measurement using a UV-VIS-NIR spectrophotometer, and photoluminescence spectroscopy. Fourier transforms infrared and energy dispersion X-rays were used to analyze the structure. It has been determined that the Al layer increased the PL's intensity by about 60% when compared to the PS. The presence of stable Si-Al bonds is responsible for the enhancements in characteristics. I-V characteristics of Au/Al: PS/Au device displayed a lower dark and higher photocurrent with a Schottky barrier and ideality factor equal to 0.88 and 2.37, respectively. The prepared photodetector displayed a higher sensitivity when exposed to a UV lamp (395 nm) at reverse bias. In consequence, the passivated Al layer enhances the PS's optical and electrical properties.