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Investigation of interface states in Al/SiO2/p-Si (MIS) structures with 50 and 826 Å SiO2 interfacial layer using admittance spectroscopy method

Ş. ALTINDAL1, Y. ŞAFAK ASAR1,* , A. KAYA1, Z. SÖNMEZ1

Affiliation

  1. Faculty of Science, Gazi University, Physics Department, 06500, Ankara-Turkey

Abstract

In order to achieve a better understanding of the effects of interface states (Nss) and their relaxation time (τ),thickness of interfacial oxide layer (SiO2) and series resistance (Rs) on the electrical characteristics, two type Al/SiO2/p-Si (MIS) structures were fabricated with thin (50 Å) and thicker (826 Å) and they called as sample A and sample B, respectively. The energy density distribution profile of the Nss and their τ and capture cross section (σp) 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 Nss located Si/SiO2 interface and interfacial oxide layer. The values of Nss, τ and σp changed from 9.55x1013 to 5.82x1013 eV-1cm-2, 6.31x10-6 to 1.58x10-6 s, and 3.55x10-21 to 1.27x10-15 cm-2 for sample A, 4.29x1013 to 3.36x1012 eV-1cm-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 Nss 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 Nss. In addition, the measured C-V and G/ω-V characteristics of these devices were corrected as Cc-V and Gc/ω-V to eliminate the effect of Rs..

Keywords

MIS structure, Admittance-spectroscopy method, Interfacial layer, Relaxation time and capture cross section.

Submitted at: Feb. 6, 2012
Accepted at: Oct. 30, 2012

Citation

Ş. ALTINDAL, Y. ŞAFAK ASAR, A. KAYA, Z. SÖNMEZ, Investigation of interface states in Al/SiO2/p-Si (MIS) structures with 50 and 826 Å SiO2 interfacial layer using admittance spectroscopy method, Journal of Optoelectronics and Advanced Materials Vol. 14, Iss. 11-12, pp. 998-1004 (2012)