The effects of the temperature on current–voltage characteristics of Sn/polypyrrole/n-Si structures

Abstract

Sn/polypyrrole (PPy)/n-Si structure has been fabricated and the I– V characteristics of the structure have been measured in the temperature range 90–300 K. It is shown that the PPy is a good rectifying contact on the n-Si semiconductor. The analysis of I– V characteristics based on the thermionic emission (TE) mechanism has revealed an abnormal decrease of zero-bias barrier height and increase of the ideality factor at lower temperatures. This behavior has been interpreted by the assumption of a Gaussian distribution of barrier heights due to barrier height imhomogeneities that prevail at the interface. Φ b0 versus 1/ T plot has been used for the evidence of Gaussian distribution of the barrier height. The values of Φ ¯ b 0 =0.862 eV and σ 0 = 0.0924 V for the mean barrier height and zero-bias standard deviation have been obtained from the plot. Thus, a modified ln( I 0/ T 2) − q 2 σ 0 2 /2 k 2 T 2 versus 1/ T plot has given Φ ¯ b 0 and A * values as 0.824 eV and 19.17 A/cm 2 K 2, respectively. It can be concluded that Sn/PPy/n-Si structure has a good rectifying contact and the temperature dependence of I– V characteristics of the Schottky barrier on n-Si successfully have been explained on the basis of TE mechanism with Gaussian distribution of the barrier heights.