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

We have fabricated two types of Schottky barrier(SBDs),Au/SnO₂/n-Si (MIS1) and Al/SnO₂/p-Si (MIS2), to investigate the surface (N_ss) and series resistance (R_s) effect on main electrical parameters such as zero-bias barrier height (Φ_Bo) 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, Φ_Bo, n, N_ss and R_s 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 N_ss and interfacial insulator layer at the metal/semiconductor interface. In addition, the temperature dependence energy density distribution profiles of N_ss 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 (Φ_e) and R_s. Experimental results show that both N_ss and R_s 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 R_s, n and N_ss compared to n-type SBD (MIS1), which results in higher current at both 200 and 295 K.