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Key to producing quantum computing devices based on the atomistic placement of dopants in silicon by scanning tunneling microscope (STM) lithography is the formation of embedded highly doped Si:P delta layers (δ-layers). This study investigates the transport behavior and the electron-electron interaction (EEI) physics in the highly doped regions of embedded Si:P-based devices by means of self-consistent magnetotransport measurements. From careful magnetotransport study at low temperature and analysis of the weak localization (WL) signal, we extract parameters associated with the electronic transport that offer a meaningful quantitative characterization of δ-layer quality and dopant diffusion. In addition, by examining EEI behaviors in a set of samples with embedded Si:P delta layers produced with different PH3 exposure procedures prior to Si encapsulation, we show that the charge carriers behave as 2DEGs in embedded Si:P δ-layers in samples grown with a locking layer to bolster confinement of the dopants, while samples grown without a locking layer demonstrate several signatures of transport and EEI in a 3D system. This work establishes the relationship between δ-layer confinement and EEI on screening lengths, the understanding of which will lead to improvements in the control of electrostatic gating of and tunneling transport through Si:P single atom transistors.
Physical Review B
quantum, quantum transport, nanoelectronics, silicon, doping, weak-localization