Who: Sananda Biswas International (Centre for Theoretical Physics (ICTP), Trieste, Italy)
Place: Donostia International Physics Center (DIPC). Paseo Manuel de Lardizabal, 4, Donostia
Date: Friday, 20 March 2015, 12:00
Density functional theory based strategies for patterning and etching of semiconductor surfaces With the continual drive to miniaturize electronic components, it has become necessary to have the ability to carve out features on semiconductor surfaces. At present, this is done using mainly a gas mixture containing halogen as an etchant. In this talk I will focus on two strategies to tune chemical properties of semiconductor surfaces to obtain new surface morphologies: patterning and etching of Si(001) by bromine. In the first part of my talk, I will focus on patterning. Here, we show that it is possible to tune patterning conditions by co-adsorption of gases. In the second part, I will focus on the atomistic picture of etching by which atoms are removed from the Si(100) surface by bromine via the formation of volatile silicon dibromide. We observe that the effective reaction barrier for supersaturation etching (where bromine coverage is greater than one) is lower compared to the effective barrier for conventional etching (where bromine coverage is less than equal to one). This counter-intuitive result is explained by the large steric interactions of the bromine atoms.