Tuning the Electronic Properties of a Boron-Doped Si(111) Surface by Self-Assembling of Trimesic Acid

The influence of self-assembled trimesic acid (TMA) on the electronic properties of a heavily boron-doped silicon surface was investigated using first-principles DFT calculations. Out results demonstrate that the adsorption of isolated TMA molecules, small molecular islands, or complete monolayers is characterized by significant adsorption energy and electron charge transfer to the Si-B interface, while the bonding character of TMA to the surface remains essentially noncovalent. The stability of the adsorbed species was ensured by an attractive interaction from the Si-B interface but also through the formation of hydrogen bonds between TMA units. Beyond this significant stability of the different TMA adlayers, the weak dispersion and the energy level position of states associated with the TMA moieties observed in the band gap region of the Si-B interface suggest that the adsorbed layer can be used: to tune the electronic properties of the substrate.