An investigation of the temperature dependence of the resistivity of PPy(p-TS) and the I-V characteristics of the PPy/n-Si heterojunctions

• Main Author: Manzano, Maria Carla F.
• Format: text
• Language: English
• Published: Animo Repository 1995
• Subjects: Temperature; Pyrrole; Polymers and polymerization; Electric conductivity; Semiconductors; Physics
• Online Access: https://animorepository.dlsu.edu.ph/etd_masteral/1781
• Institution: De La Salle University

Rectifying heterojunctions of PPy(p-TS) with n-Si were formed by mechanical contact. The IV characteristics of the junctions were measured and analyzed. Barrier heights ranging from 0.74 - 0.77 were obtained. The junctions were found to have reverse current densities in the range 1.53 - 3.81 x 10 to the negative 6 A/square centimeter, with ideality factors of 18.0 to 31.1. The PPy(p-TS) films were prepared by electrochemical synthesis from aqueous solutions under constant current conditions.The PPy(p-TS)/n-Si heterojunctions that were exposed to air for 4 hours showed ageing. The slope of the I-V curves of the junctions decreases with time because of the formations of an oxide layer at the interface.Attempts were also made to form PPy(p-TS) junctions with n-Si by electrochemical deposition of PPy(p-TS) on n-Si wafer used as an electrode. However, the adhesion of the PPy(p-TS) films on the n-Si was not good and it was not possible to obtain I-V characteristics on these samples. However, a measurement of the resistivity of these films as a function of temperature showed a T to -1/2 and T to -1/4 dependence on the 1n p, consistent with two-dimensional and three-dimensional variable range hopping mechanism for electrical conduction. The mean hopping distance ranged from 5-8 Angstrom. The hopping activation energy at 300K was found to be between 30.1 and 47.7 meV, and the density of states at the Fermi level, from 10 to the 21 power, to 10 to the 22 power, eV to negative 1, negative 3 centimeter.