Analysis of Randomly Spaced Quantum Dots with Oxide Overlayers Using Spectroscopic Ellipsometry

Data obtained by spectroscopic ellipsometry (SE) on a random array of oxide-coated InAs quantum dots (QDs) are analyzed by rigorous coupled-wave analysis (RCWA). RWCA is an important method of precisely determining the geometric parameters of patterned periodic structures, but has been applied only rarely to random systems and not previously to a random distribution of QDs covered with an oxide overlayer. We find our model calculations to be in reasonable agreement with data, showing that RCWA is a useful approach for extracting average values of the size, interval, distribution density, shape, and possibly composition of QD structures even when not periodically arranged.