Impact of Molecular Dynamics (MD) in Semiconductor Materials Research

Precision synthesis and processing of semiconductor compound alloys with controlled composition in multilayered device structures is critical to many energy conversion and information technologies including solid state light, power electronics, solar cells, satellite communications as well as light weight optics. As one example, a high indium content is required for the In_xGa_1-xN/GaN solid state light devices to fill the “green” light gap so that they can efficiently emit white light suitable for human eyes. Despite extensive studies, however, an abrupt reduction in the green light emission efficiency of In_xGa_1-xN films occurs when the indium content is increased to x &gt; 0.2. As another sample, the CdS/CdTe-based solar cells can produce energy with a relatively low cost and therefore they can profoundly change the energy suppliers if their energy conversion efficiency achieved today can be further improved. The key to improve either the In_xGa_1-xN/GaN or the CdS/CdTe devices is to reduce or control the various defects formed during synthesis including dislocations and grain boundaries. To achieve this, the formation mechanisms of defects must be understood in atomistic details. These mechanisms are often difficult to explore using experimental approaches alone. Molecular dynamics simulation tools provide a powerful alternative approach to study atomistic assembly in greater details. In this presentation, we provide an overview of our past molecular dynamics simulation work on structure evolution during synthesis of semiconductor materials including multilayered compound alloys and some advanced knowledge gathered on processing of semiconductors. First, we describe molecular dynamics simulation methods of thin film growth. Next, we introduce an example semiconductor interatomic potential database. We then use the simulations methods to study a variety of problems relevant to the synthesis of semiconductor compound alloys including graphene growth, In_xGa_1-xN/GaN growth, CdTe/CdS growth, CdTe/GaAs growth, synthesis of Si crystals and SiC, atomistically-informed misfit dislocation theory, and dislocation migration in CdTe. MD has paved strong footings to a newer area of research to study “high pressure phase transformation” which seems to be most common mechanism of ductility in semiconductors beside dislocation nucleation. The impact of molecular dynamics simulations in semiconductor materials research is discussed.<br/> <br/>Sandia National Laboratories is a multi-mission laboratory managed and operated by National Technology and Engineering Solutions of Sandia, LLC., a wholly owned subsidiary of Honeywell International, Inc., for the U.S. Department of Energy’s National Nuclear Security Administration under contract DE-NA-0003525. The views expressed in the article do not necessarily represent the views of the U.S. Department of Energy or the United States Government.