Electrical properties dependent on Schottky diode Pd/PSC-pSi(100) based on hydrocarbon gas sensor

摘要

In this paper we present the study of a Schottky diode gas sensing by using porous SiC films with palladium as a catalytic metal. The Schottky diodes were used for the first time for hydrocarbon (C_2H_6) gas sensing. The properties of the porous SiC films formed by electrochemical method were investigated by scanning electron microscopy (SEM). The electrical measurements were made at room temperature (295 K) in different ambient. The effect of the porous surface structure was investigated by evaluating electrical parameters such as the ideality factor (n), barrier height (φB_P) and series resistance (R_s). The porous layer significantly affects the electrical properties of the Schottky diodes. Analysis of current-voltage (Ⅰ-Ⅴ) characteristics showed that the forward current might be described by a classical thermal emission theory. The ideality factor determined by theⅠ-Ⅴ characteristics was found to be dependent on the SiC thickness. For a thinner SiC layer (0.16 urn), the electrical parameters n was found around 1.135, 0.7041 eV for a barrier height and 45 Ω for a series resistance, but for a thicker one (1.6 μm) n, φB_p and Rs were 1.368, 0.7756 eV and 130Ω, respectively. The low value of the series resistance obtained using Cheung's method clearly indicated the high performance of the Schottky diode for thinner SiC layer. This effect showed the uniformity of the SiC layer. Finally, sensitivity around 66 % and selectivity of the sensors were reached by using the PSC layer at low voltages below 0.5 Volt.