Effect of Sb, Tb3+ Doping on Optical and Electrical Performances of SnO2 and Si Based Schottky Diodes

Abstract

Abstract(Sb, Tb3+)-doped SnO2 thin films were deposited on monocrystalline silicon (Si) and on porous silicon (PS) layer from sol-gel spin coating method. The photoluminescence spectrum shows that Tb3+ ions presents higher emission with the PS layer. The fabricated junctions are treated as a metal-semiconductor (MS) Schottky diodes. The current–voltage (I-V) characteristics of SnO2:Sb/p-Si (D1), SnO2:Sb:Tb3+/p-Si (D2) and SnO2:Sb:Tb3+/PS (p) (D3) were measured for these diodes at room temperature. Electronic parameters such as ideality factor, barrier height and series resistance were calculated and compared for the main junctions. Based on the thermoionic emission model, it appears that the contacts presents non-ideal I-V behaviour with a relatively high values of ideality factor (n\u2009=\u200912 for Si based diode, and n\u2009=\u200924 for PS based diode) and a relatively large values of series resistance RS (RS\u2009=\u20092 103\xa0Ω for D3). After the incorporation of Tb3+, the junction characteristics show that the formed diode exhibits high forward current density and a decrease in the series resistance RS (RS\u2009=\u2009600\xa0Ω for D2). The non-ideality character of the elaborated MS junctions seems to be principally due to the effects of the interface. The relatively high values of the ideality factor was attributed to the sharing of the applied voltage V by a diffusion potential (VD) across the semiconductor space charge region and a potential (Vi) devoted to the interfacial layer formed between the silicon and the tin oxide. The trapped-limited current was found to dominate the current transport mechanisms through the fabricated junctions. The above results highlight the role of the interfacial layer and interface states in the determination of the electrical performance of Sb-doped SnO2/p-Si, (Sb, Tb3+) co-doped SnO2/p-Si and (Sb, Tb3+) co-doped SnO2/PS(p). They show that the simultaneous presence of Tb3+ ions and porous silicon layer allows an obvious enhancement of both optical and electrical properties of the main junction increasing then the applicability of SnO2/silicon based devices.