Multiscale Materials Modeling Group
Universidad de Valladolid
Project VA331U14, funded by 
Semiconductors are intentionally or unintentionally exposed to radiation of energetic particles during processing (ion implantation during the doping step) or during operation (radiation detectors, devices exposed to cosmic radiation). The displacement of atoms of a crystalline solid by their collision with energetic particles produces structural defects. The presence of these defects is often associated with the degradation of devices (leakage currents, reduced efficiency), but in some cases are also beneficial (formation of nanostructures, defect-induced photoluminescence). The variety of defects that can coexist and the lack of knowledge of the precise nature of defects causing certain effects difficults the optimization of devices.
The aim of this project is to determine the nature and properties of the defects responsible for the degradation of silicon semiconductor devices under irradiation and of the defects associated with implanted silicon photoluminescent signals. We propose to address the problem using multiscale simulation techniques for (i) generating defects by irradiation and analizing their evolution during subsequent annealings without making any assumptions on initial defect configurations using classical molecular dynamics; (ii) calculate the electrical and optical properties using techniques ab-initio; and (iii) reproduce the experimental conditions of irradiation experiments by kinetic Monte Carlo simulations. The results from this project have application in (i) improving experimental characterization techniques to correlate certain effects with specific defects, and (ii) design optimization strategies devices.