TY - JOUR
T1 - Molecular and Ionic Dipole Effects on the Electronic Properties of Si-/SiO2-Grafted Alkylamine Monolayers
AU - Gankin, Alina
AU - Sfez, Ruthy
AU - Mervinetsky, Evgeniy
AU - Buchwald, Jörg
AU - Dianat, Arezoo
AU - Medrano Sandonas, Leonardo
AU - Gutierrez, Rafael
AU - Cuniberti, Gianaurelio
AU - Yitzchaik, Shlomo
N1 - Publisher Copyright:
© 2017 American Chemical Society.
PY - 2017/12/27
Y1 - 2017/12/27
N2 - In this work, we demonstrate the tunability of electronic properties of Si/SiO2 substrates by molecular and ionic surface modifications. The changes in the electronic properties such as the work function (WF) and electron affinity were experimentally measured by the contact potential difference technique and theoretically supported by density functional theory calculations. We attribute these molecular electronic effects mainly to the variations of molecular and surface dipoles of the ionic and neutral species. We have previously shown that for the alkylhalide monolayers, changing the tail group from Cl to I decreased the WF of the substrate. Here, we report on the opposite trend of WF changes, that is, the increase of the WF, obtained by using the anions of these halides from Cl- to I-. This trend was observed on self-assembled alkylammonium halide (-NH3+ X-, where X- = Cl-, Br-, or I-) monolayer-modified substrates. The monolayer's formation was supported by ellipsometry measurements, X-ray photoelectron spectroscopy, and atomic force microscopy. Comparison of the theoretical and experimental data suggests that the ionic surface dipole depends mainly on the polarizability and the position of the counter halide anion along with the organization and packaging of the layer. The described ionic modification can be easily used for facile tailoring and design of the electronic properties Si/SiO2 substrates for various device applications.
AB - In this work, we demonstrate the tunability of electronic properties of Si/SiO2 substrates by molecular and ionic surface modifications. The changes in the electronic properties such as the work function (WF) and electron affinity were experimentally measured by the contact potential difference technique and theoretically supported by density functional theory calculations. We attribute these molecular electronic effects mainly to the variations of molecular and surface dipoles of the ionic and neutral species. We have previously shown that for the alkylhalide monolayers, changing the tail group from Cl to I decreased the WF of the substrate. Here, we report on the opposite trend of WF changes, that is, the increase of the WF, obtained by using the anions of these halides from Cl- to I-. This trend was observed on self-assembled alkylammonium halide (-NH3+ X-, where X- = Cl-, Br-, or I-) monolayer-modified substrates. The monolayer's formation was supported by ellipsometry measurements, X-ray photoelectron spectroscopy, and atomic force microscopy. Comparison of the theoretical and experimental data suggests that the ionic surface dipole depends mainly on the polarizability and the position of the counter halide anion along with the organization and packaging of the layer. The described ionic modification can be easily used for facile tailoring and design of the electronic properties Si/SiO2 substrates for various device applications.
KW - DFT
KW - contact potential difference
KW - ionic dipole
KW - molecular dipole
KW - self-assembled monolayer
KW - work function
UR - http://www.scopus.com/inward/record.url?scp=85040042319&partnerID=8YFLogxK
U2 - 10.1021/acsami.7b12218
DO - 10.1021/acsami.7b12218
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C2 - 29206026
AN - SCOPUS:85040042319
SN - 1944-8244
VL - 9
SP - 44873
EP - 44879
JO - ACS Applied Materials and Interfaces
JF - ACS Applied Materials and Interfaces
IS - 51
ER -