Revealing quantum effects in highly conductive δ-layer systems

Thin, high-density layers of dopants in semiconductors, known as δ-layer systems, have recently attracted attention as a platform for exploration of the future quantum and classical computing when patterned in plane with atomic precision. However, there are many aspects of the conductive properties of these systems that are still unknown. Here we present an open-system quantum transport treatment to investigate the local density of electron states and the conductive properties of the δ-layer systems. A successful application of this treatment to phosphorous δ-layer in silicon both explains the origin of recently-observed shallow sub-bands and reproduces the sheet resistance values measured by different experimental groups. Further analysis reveals two main quantum-mechanical effects: 1) the existence of spatially distinct layers of free electrons with different average energies; 2) significant dependence of sheet resistance on the δ-layer thickness for a fixed sheet charge density. A solution to performance related challenges posed by nanoscale field effect transistors is to consider atomically thin impurity layers in Si-based devices however there are many aspects of the conductive properties that are still unknown. Here, the authors develop an open system quantum transport method to investigate the local density electronic states of P-doped Si revealing the role of scattering, thickness and doping density.