Preparation and Characterization of (Au/n-Sn /Si /Si/Al) MIS Device for Optoelectronic Application

SnO2 thin films were prepared by using rapid thermal oxidation (RTO) of Sn at oxidation temperature 873？K and oxidation time 90？sec on semiconductor n-type and p-type silicon substrate. In order to characterize the prepared device, the electrical properties have been measured which revealed that the barrier height is greatly depended on interfacial layer thickness (SiO2). The value of peak response (n-SnO2/SiO2/n-Si) device was 0.16？A/W which is greater than that of (n-SnO2/SiO2/p-Si) device whose value was 0.12？A/W, while the rise time was found to be shorter. 1. Introduction Transparent Conductive Oxides (TCOs) have been extensively studied due to their important technological applications, such as electrochromatic displays, solar cells, and other optoelectronic devices [1]. For these applications, the TCOs should present a combination of high transparency in the visible spectral range and low electrical resistivity. An example of these oxides is the tin oxide (SnO2) that shows high transmittance in the visible region and a poor conductivity (σ ~ 102–103？Ω？1？cm？1) at room temperature (~300？K). Moreover, value is unstable during its operation due to the reaction of oxygen vacancies in the SnO2 lattice with ambient oxygen [2]. SnO2 layers can be deposited using various methods: sputtering [3], pulsed excimer laser ablation deposition (PLAD) [4], chemical vapour deposition (CVD) [5, 6], and spray pyrolysis [7–10]. Tin oxide thin films are n-type semiconductors with a direct optical band gap of about 3.87–4.3？eV [11–14]. Further, its refractive index lies in between 1.9 and 2.0 and hence it can be used as an antireflection (AR) coating. Thermal oxidation is a chemical process, where silicon dioxide (SiO2) is grown in an ambient with elevated temperatures. A simple form of thermal oxidation even takes place at room temperature, if silicon is exposed to an oxygen or air ambient. There, a thin native oxide layer with (0.5–1？nm) will form on the surface rapidly. After that, the growth slows down and effectively stops after a few hours with a final thickness in the order of (1-2？nm), because the oxygen atoms have too small energy at room temperature to diffuse through the already formed oxide layer. The reports on the physical properties of other oxide films prepared by thermal oxidation of metallic films revealed a strong dependence of these properties on the heating rate during oxidation process [15]. The desired characteristics and requirements of the fabricated oxide can be mainly influenced by the used oxidant species. For a chosen oxidant species the