Misfit accommodation in a single interface atomic layer at a highly lattice-mismatched InN/GaN

Heterostructures of covalent semiconductors provide an invaluable platform for synthesizing the distinct properties of materials, leading to unprecedented functions in electronic and optoelectronic devices. The main challenge has been to forge high-quality interfaces of the heterostructures that guarantee the designed properties. To date, high-quality interfaces have been attained in heterostructures with a lattice mismatch of less than a few percent. However, for highly lattice-mismatched interfaces, such as InN/GaN (0001) (11.1% mismatch), interfacial structures remain unknown. Here, we investigate the atomic structure of the InN/GaN interface using atomic-resolution transmission electron microscopy and large-scale density-functional calculations. Our findings show that an interface structure without any misfit dislocations is formed, where an InN single monolayer at the interface accommodates the entire misfit. We argue that the mechanism underlying the formation of this interface monolayer is the flexibility of the group III–nitrogen bond network.