The effects of surface states and series resistance on the performance of Au/SnO2/n-Si and Al/SnO2/p-Si (MIS) Schottky barrier diodes

Abstract

We have fabricated two types of Schottky barrier(SBDs),Au/SnO2/n-Si (MIS1) and Al/SnO2/p-Si (MIS2), to investigate the surface (Nss) and series resistance (Rs) effect on main electrical parameters such as zero-bias barrier height (ΦBo) and ideality factor (n) for these SBDs. The forward and reverse bias current–voltage (I–V) characteristics of them were measured at 200 and 295 K, and experimental results were compared with each other. At temperatures of 200 and 295 K, ΦBo, n, Nss and Rs for MIS1 Schottky diodes (SDs) ranged from 0.393 to 0.585 eV, 5.70 to 4.75, 5.42×1013 to 4.27×1013 eV−1 cm−2 and 514 to 388 Ω, respectively, whereas for MIS2 they ranged from 0.377 to 0.556 eV, 3.58 to 2.1, 1.25×1014 to 3.30×1014 eV−1 cm−2 and 312 to 290 Ω, respectively. The values of n for two types of SBDs are rather than unity and this behavior has been attributed to the particular distribution of Nss and interfacial insulator layer at the metal/semiconductor interface. In addition, the temperature dependence energy density distribution profiles of Nss for both MIS1 and MIS2 SBDs were obtained from the forward bias I–V characteristics by taking into account the bias dependence of effective barrier height (Φe) and Rs. Experimental results show that both Nss and Rs values should be taken into account in the forward bias I–V characteristics. It has been concluded that the p-type SBD (MIS2) shows a lower barrier height (BH), lower Rs, n and Nss compared to n-type SBD (MIS1), which results in higher current at both 200 and 295 K.