This work consists in first-principles calculations applied to the study of bulk heterojunctions composed of organic molecules deposited onto Si surface. These molecules are composed of an insulating alkyl chain completed by ap-bonded headgroup. A metal layer finally caps everything, and formsa Schottky contact.

Thus, calculations were carried out for a Si-molecule-metal multilayer of the type experimentally realized at the IEMN laboratories. We calculated the energy band and vacuum-level alignment between Si, molecular semiconductor, and metal layers, according to the bulk semiconductor theory, in order to describe the electronic structure and electrostatic properties of such complex.
The electron density and the electrostatic potential were evaluatedacross the various interfaces of the multilayer. We compared the open circuit arrangement (a void slab of about 10 Å separates the top and bottom free surfaces) tothe closed circuit one(an additional Al-Si interface is present). Our aim is to underline the role of the interface structure and defects in establishing such quantities as the relative potential and wavefunction drop, the attending (mis)alignment of vacuum levels, and the band offset at the organic-inorganic semiconductor interface.

Our model mimics the simplest of the experimental arrangements.
Stacked along the supercell (001) direction, we find: four 2x2 planar units of Si (100), with the bottom free surface terminated by H; one layer of silane-terminated, 8-mer alkyl chain, with a phenyl head linked by a double-oxygen bridge, or H₃Si(CH₂)₈COO–CH₂(1,phenyl); and four 2x2 planar units of Al (100). The resulting inverse density of the molecular monolayer is equal to 29.2 Ų/mol, a value well in the range of the experimental data.

• Legal notice:
  

  Copyright (c) Pielaszek Research, all rights reserved.
  The above materials, including auxiliary resources, are subject to Publisher's copyright and the Author(s) intellectual rights. Without limiting Author(s) rights under respective Copyright Transfer Agreement, no part of the above documents may be reproduced without the express written permission of Pielaszek Research, the Publisher. Express permission from the Author(s) is required to use the above materials for academic purposes, such as lectures or scientific presentations.
  In every case, proper references including Author(s) name(s) and URL of this webpage: https://science24.com/paper/15805 must be provided.

1. Contact Resistance Limited Thermal Transport of Carbon Nanotube Mats
2. Shape and faceting of Si nanocrystals embedded in an amorphous glass matrix