Modeling the initial monolayer formation in thermally localized surface deposition

In atomic layer deposition (ALD), thin layers of materials are deposited on a substrate with atomic layer precision in the vertical direction. The ability to control layer growth in the lateral direction as well is expected to greatly increase the potential of ALD as a path to the bottom-up additive fabrication of electronic devices like solar panels and organic light-emitting diode displays. We explore the possibility of controlling the lateral growth by modifying the temperature profile on the substrate using, for instance, pulsed lasers. This maskless technique keeps the majority of the substrate at a low temperature suppressing one of the chemical half-reactions, while in a small, localized area, the substrate is heated, which allows the reaction to proceed at a higher rate. We test this idea with course-grained computational models that model the control of the temperature by various illumination protocols and simulate the nucleation and growth of the initial monolayer within this inhomogeneous temperature distribution. Our results suggest that the location and the extent of deposition can, in principle, be localized and controlled and address operational regimes in which a thin conducting line may be obtained.