PROPERTIES OF HETEROJUNCTION OF SI/POLY(3-METHYLTHIOPHENE) AS A FUNCTION OF POLYMERIZATION CONDITION

A detailed analysis of poly(3-methylthiophene) (P3MeT) films deposited on a n-Si substrate is presented. In order to perform junction analysis, potentiometric measurements during the growth of the film, current-voltage measurements, degradation of electrical properties, FT-IR (Fourier transform infrared) measurements, and SEM (scanning electron microscope) observations are studied. New insights into the junction are obtained. The rectifying behavior is greatly improved by employing sandblasted n-Si as a substrate, compared with a nonsandblasted n-Si substrate. Based on these results, junction formation is described as the evolution of covalent bond formation between hydroxy groups on the n-Si surface and a polymer film. The results are supported by FT-IR measurements of the sandblasted n-Si surface. A covalent bond destruction model is used to describe degradation behavior of the P3MeT/sandblasted n-Si heterojunction.