2D Materials Integration with Silicon as 2D-3D Heterostructure Architecture Enabled by Quantum Tunneling

In-line with the concept of three-dimensional (3D) hybrid integration, the combination of silicon-based circuits with two-dimensional (2D) material-based device architectures has emerged as an appealing topic. This fusion holds the promise in innovative electronics and optoelectronics with novel functions, higher integration level, fast speed, and many other benefits that are intangible in conventional designs. Nonetheless, the integration of silicon and 2D materials in a 3D configuration encounters a problem of substantial contact resistance. Earlier investigations suggested that the presence of van der Waals gap and in-gap states could be responsible for the poor contact. In this study, we present an alternative approach to enhance contact quality. In essence, instead of eliminating the van der Waals gap between silicon and 2D materials, we treat the gap as a quantum tunneling barrier and manage to increase the quantum tunneling efficiency. By tuning the Fermi-surface alignment and minimizing the charge carrier momenta mismatch, we effectively reduce the contact resistance between silicon and graphene achieving nearly ideal ohmic contact. Furthermore, we characterize the phonon-assisted inelastic transport process on this silicon-graphene interface and demonstrate its positive effects in enhancing the contact conductivity. This research provides a feasible and versatile approach for high-quality 3D-2D contact fabrication towards the hybrid integration of dissimilar materials with advanced functionalities in the field of electronics and optoelectronics.