Study of the electroluminescent properties of crystalline silicon wafers in devices based on junctions of indium-doped zinc oxide and porous silicon

In this study we obtained electroluminescent devices (ELD) based on junctions of indium doped zinc oxide (ZnO:In) and porous silicon layers (PSL). The PSL were obtained by electrochemical etching with different types and resistivities of silicon wafers. In the visible part of the electromagnetic spectrum, the porous silicon (PS) exhibits photoluminescence (PL) that is centered around 680 nm. Once the devices were obtained, they were optically and electrically characterized. The PSL were coated with ZnO:In film, which was gotten by the ultrasonic spray pyrolysis technique (USP). When the devices were electrically polarized they showed optical response in the regions corresponding to the visible and infrared band of the electromagnetic spectrum. The observed electroluminescence (EL) in the visible region goes from 400 to 750 nm and the corresponding emission of the infrared part is around 750–1150 nm. The devices presented luminescent spots on the surface which were visible to the naked eye. The analysis of the results shows that the emission source in the visible part is attributed to the filaments present in the PS, and also to the ZnO:In films and the emission in the infrared part is associated to the silicon substrate. The electrical characterization was carried out by current–voltage curves (I–V) that show in the devices a rectifying behavior.