Electrical and structural characterization of PS/ZnO heterojunctions

F. A. GARCES; F. MORA; R.R. KOROPECKI; R. D. ARCE

Cancún

Congreso; XXI International Materials Research Congress; 2012

IMRC

In this work we present the electrical and photonic characterization of a Porous Silicon/TCO (Transparent Conductor Oxide) junction obtained by the deposition of ZnO onto porous silicon (PS), using the sol-gel technique. The porous silicon was prepared by the electrochemical anodization of a silicon wafer. The anodization conditions were chosen so as to produce a macroporous system, with pore size ranging in 1 to 1.2 μm diameter. The transport of charge carriers through the interface was studied from measurements of current-voltage curves in dark and under illumination. The ZnO was doped with magnesium and aluminium. We analyzed the effects of the dopant concentration on the electrical properties of the junction. By fitting the J-V characteristic we evaluated the series resistance, diode ideality factor, reverse saturation current and photogenerated current. The values obtained for the ideality factor are quite high. This behavior can be attributed to formation of thin layer of SiO2 at PS/ZnO. Interface1. The results were analysed in relation with the structural properties of the grown films, such as lattice parameter and the crystallite size obtained by X-ray diffraction measurements. Additionally, the light emission of PS/ZnO heterojunction was measured under the passage of electrical current for different applied voltages. The measured signal was collected by a photodiode as a function of time. The light intensity increases with increasing applied voltage, following a trend similar to that observed for the current in the J-V curves. This phenomenon, known as electroluminescence.