(71e) Modeling of Silicon Dopant Activation in Ingaas
Driven by interest from both the semiconductor and energy industries, III-V materials, especially ternary compounds such as InGaAs (on Si), have attracted a lot of attention because of their direct electronic band gap for most of these materials and their outstanding electrical conductivity. More practically, they offer a potential solution to the increasing problem of over-heating in current transistors. Compared to Si, III-V compound semiconductors (e.g., GaAs or InP) have lower conduction band effective mass and higher electron mobility. In particular, a ternary compound such as In0.53Ga0.47As, which is lattice-matched to InP, can be integrated on Si substrates to support device fabrication. However, preliminary experimental investigations show only poor activation of Si dopants in InGaAs (~15%), which limits their usefulness. Our atomic-scale simulations are intended to unravel the reasons behind the poor activation. We have used first-principles density-functional theory and semi-empirical molecular modeling using Tersoff potentials for the multi-scale modeling. We have parameterized Tersoff potentials for Si-X (X = In, Ga, and As) interactions. This parameterization allowed us to perform diffusion calculations on large systems. Calculation of substitutional and interstitial defect formation energies provides a picture of the preferences of Si atoms to occupy substitutional and interstitial cation sites in InGaAs. We have evaluated the formation energy dependence up to the second nearest neighbors. The nudged elastic band (NEB) method is used to calculate migration energies, which ultimately leads us to activation energies.