Investigation of interface states in Al/SiO_2/p-Si (MIS) structures with 50 and 826 ? SiO_2 interfacial layer using admittance spectroscopy method

摘要

In order to achieve a better understanding of the effects of interface states (N_(ss)) and their relaxation time (τ),thickness of interfacial oxide layer (SiO2_) and series resistance (R_s) on the electrical characteristics, two type Al/SiO_2/p-Si (MIS) structures were fabricated with thin (50 ?) and thicker (826 ?) and they called as sample A and sample B, respectively. The energy density distribution profile of the N_(ss) and their τ and capture cross section (ω_p) of these structures have been investigated using admittance spectroscopy method which is concluding capacitance-voltage (C-V) and conductancevoltage (G/ω-V) in the wide frequency range of 10 kHz-1 MHz. The increase in capacitance especially at low frequencies and the peak behavior in G/ω-V plots in the depletion region can be attributed to the existence of N_(ss) located Si/SiO_2 interface and interfacial oxide layer. The values of N_(ss), τ and ω_p changed from 9.55x10~(13) to 5.82x10~(13) eV~(-1)cm~(-2), 6.31x10~(-6) to 1.58x10~(-6) s, and 3.55x10~(-21) to 1.27x10~(-15) cm~(-2) for sample A, 4.29x10~(13) to 3.36x10~(12) eV~(-1)cm~(-2), 6.31x10~(-6) to 1.58x10~(-6) s, and 6.65x10~(-21) to 6.69x10~(-15) cm~(-2) for sample B, respectively. It is clear that the values of N_(ss) in sample A are almost one order higher than that in sample B. This indicate that a thick insulator layer at M/S interface can be considerably reduced the magnitude of N_(ss). In addition, the measured C-V and G/ω-V characteristics of these devices were corrected as C_c-V and G_c/ω-V to eliminate the effect of R_s.