All crystals contain line defects, called dislocations. In semiconductor devices, their presence is typically detrimental to device performance, and therefore crystal growers attempt to have as few dislocations as possible. But what if dislocations were useful in their own right? For decades, their electronic structure had been speculated upon, but not until very recently with advances in computing power and atomistic simulations, could the energy levels due to dislocations be accurately studied. Experimentally it is known that dislocations in some II-VI semiconductors, e.g. ZnS, display extraodinary dependence on optical excitation, where ZnS becomes more plastic in the dark than in the light. We are collaborating with experts in computational atomistic simulations to explore the electronic, optical, properties of dislocations in ZnS to understand the photoplasticity and validate the electronic structure predictions.
Starting from first principles, using modern density functional theory (DFT) techniques, our collaborators have computed the electronic structure and properties of dislocations in diamond. Remarkably, the dangling bonds in some of these dislocations can form either semiconducting or metallic conduction. Electrons in these states are confined to a single atomic width, but are mobile along the dislocation line itself, demonstrating that dislocations can behave as quantum wires in diamond.
see: “Dislocations as Nature’s Quantum Wires”, Genlik, Myers, Ghazisaeidi, arxiv:2210.12224