1019107-32-4Relevant articles and documents
Variable density effect of self-assembled polarizable monolayers on the electronic properties of silicon
Peor, Naama,Sfez, Ruthy,Yitzchaik, Shlomo
, p. 4158 - 4165 (2008/09/20)
Electronic structures at the Si/SiO2/molecule interfaces were studied by Kelvin probe techniques (contact potential difference) and compared to theoretical values derived by the Helmholtz equation. Two parameters influencing the electronic properties of n-type 〈100〉 Si/SiO 2 substrates were systematically tuned: the molecular dipole of coupling agent molecules comprising the layer and the surface coverage of the chromophoric layer. The first parameter was checked using direct covalent grafting of a series of trichlorosilane-containing coupling agent molecules with various end groups causing a different dipole with the same surface number density. It was found that the change in band bending (ΔBB) clearly indicated a major effect of passivation due to two-dimensional polysiloxane network formation, with minor differences resulting from the differences in the end groups' capacity to act as electron traps . The change in electron affinity (ΔEA) parameter increased upon increasing the dipole of the end group comprising the monolayer, resulting in a range of 600 mV. Moreover, a shielding effect of the aromatic spacer compared with the aliphatic spacer was found and estimated to be about 200 mV. The density effect was examined using the 4-[4-(N,N-dimethylamino phenyl)azo]pyridinium halide chromophore which has a calculated dipole of more than 10 D. It was clearly shown that upon increasing surface chromophoric coverage an increase in the electronic effects on the Si substrate was observed. However, a major consequence of depolarization was also detected while comparing the experimental and calculated values.
