Investigation of theoretical and experimental study of LDOS of thiol SAMs using scanning tunneling spectroscopy

Abstract

The surface and structural properties of SAMs of. OT, ODT, and CHT were investigated using ambient STM and electrical characterization of all SAMs was observed. Each sample was prepared with solution phase deposition method by varying immersion time from 1 hour to 10 day. Structural changes in the formation of Self-assembly monolayers (SAMs) were studied .STM studies revealed that high density SAMs are formed when we increase immersion time for aliphatic compounds and temperature for cyclic compounds. Charge transport properties are observed by calculating IV characteristics, conductance and device density of states by using Scanning Tunneling Spectroscopy (STS). These molecular devices were studied by growing the SAMs on Au (111) substrate. Fabrication of SAMs on Au (111) carried out under different parameters. Scanning Tunneling Microscope (STM) were used to study the surface morphology. STS results were giving some new electrical information about SAMs. CHT SAMs showed more conductive behavior than OT and ODT. OT and ODT has long chain system due to which they showed less conductance. STS permitted us to investigate the electrical properties of single molecular devices. The electrical study of thiol SAMs on Au (111) exhibited significant advantages due to the more stable chemical Au-S binding. These nano-sized objects attracted extensive attention from the scientific society due to their ability to serve as building blocks for nano electronic devices with, high strength, low power consumption, good performance, innovative, and unique potentials for device assembling. Simulations through DFT were also performed for OT, ODT, CHT and BMT to Study their electronic properties. Density of states for all molecules on different gold bulk were measured and compared. BMT’s conductivity was higher than rest of molecules at bulk gold. OT SAMs structure were also prepared their results were comparable to the experimental ones.