Effects of externally applied stress on the properties of quantum dot nanostructures

An array of semiconductor quantum dots is studied computationally using an approach that couples linear elasticity to electronic and optical properties. The effect of strain on the photoemission behavior of the quantum dot array is of particular interest. With a realistic quantum dot array morphology as input, finite element analysis is first used to compute electron energy levels in the domain. From these energy levels, optical conductivity is computed for the system, which is directly comparable with experimental optical absorption and emission spectra. Then, to simulate the effect of microscope tip-sample interaction, the strain field associated with a rigid cylindrical indenter is superimposed on the sample and the calculation is performed again. The computed optical spectrum shows a distinct blue-shift as a result of the indentation strain field. This observation is qualitatively and quantitatively in agreement with near field scanning optical microscopy (NSOM) experiments on the same material system. The result shows that in nanoscale semiconductor devices, mechanical and electronic properties are coupled over the same length scales and can be treated together in a coupled continuum finite element formulation.