Wave-Function Symmetry Mechanism of Quantum-Well States in Graphene Nanoribbon Heterojunctions

The construction of quantum wells (QWs) in graphene nanoribbons is interesting for applications in optoelectronics and quantum information processing, but is hindered by insufficient understanding of quantum mechanical effects in these systems. This study uses theory to reveal that, unexpectedly, electronic states confined by higher confinement energy exhibit $w\phantom{\rule{0}{0ex}}e\phantom{\rule{0}{0ex}}a\phantom{\rule{0}{0ex}}k\phantom{\rule{0}{0ex}}e\phantom{\rule{0}{0ex}}r$ quantum confinement, due to the wave-function symmetries of the electronic states from the constituent graphene nanoribbon segments. This mechanism leads to a design method for such QWs via modulation of geometric parameters and displacement between constituent nanoribbon segments.