Fabricating a semiconductor structure including forming a nanocrystalline core from a first semiconductor material, forming a nanocrystalline shell from a second, different, semiconductor material that at least partially surrounds the nanocrystalline core, wherein the nanocrystalline core and the nanocrystalline shell form a quantum dot. Fabrication further involves forming an insulator layer encapsulating the quantum dot to create a coated quantum dot, and forming an additional insulator layer on the coated quantum dot using an Atomic Layer Deposition (ALD) process.