Significant reduction in semiconductor interface resistance via interfacial atomic mixing

The contact resistance between two dissimilar semiconductors is determined by\nthe carrier transmission through their interface. Despite the ubiquitous\npresence of interfaces, quantitative simulation of charge transport across such\ninterfaces is difficult, limiting the understanding of interfacial charge\ntransport. This work employs Green's functions to study the charge transport\nacross representative Si/Ge interfaces. For perfect interfaces, it is found\nthat the transmittance is small and the contact resistance is high, not only\nbecause the mismatch of carrier pockets makes it hard to meet the momentum\nconservation requirement, but also because of the incompatible symmetries of\nthe Bloch wave functions of the two sides. In contrast, atomic mixing at the\ninterface increases the carrier transmittance as the interface roughness opens\nmany nonspecular transmission channels, which greatly reduces the contact\nresistance compared with the perfect interface. Specifically, we show that\ndisordered interfaces with certain symmetries create more nonspecular\ntransmission. The insights from our study will benefit the future design of\nhigh-performance heterostructures with low contact resistance.\n