Suppression of mid-infrared plasma resonance due to quantum confinement in delta-doped silicon

Abstract

The classical Drude model provides an accurate description of the plasma resonance of three-dimensional materials, but only partially explains two-dimensional systems where quantum mechanical effects dominate such as P:$\delta$-layers - atomically thin sheets of phosphorus dopants in silicon that induce novel electronic properties beyond traditional doping. Previously it was shown that P:$\delta$-layers produce a distinct Drude tail feature in ellipsometry measurements. However, the ellipsometric spectra could not be properly fit by modeling the $\delta$-layer as discrete layer of classical Drude metal. In particular, even for large broadening corresponding to extremely short relaxation times, a plasma resonance feature was anticipated but not evident in the experimental data. In this work, we develop a physically accurate description of this system, which reveals a general approach to designing thin films with intentionally suppressed plasma resonances. Our model takes into account the strong charge density confinement and resulting quantum mechanical description of a P:$\delta$-layer. We show that the absence of a plasma resonance feature results from a combination of two factors: i), the sharply varying charge density profile due to strong confinement in the direction of growth; and ii), the effective mass and relaxation time anisotropy due to valley degeneracy. The plasma resonance reappears when the atoms composing the $\delta$-layer are allowed to diffuse out from the plane of the layer, destroying its well-confined two-dimensional character that is critical to its novel electronic properties.

References in corpus (7)

• Quantum Simulation of an Extended Fermi-Hubbard Model Using a 2D Lattice of Dopant-based Quantum Dots
• Electronic transport in two dimensional Si:P $\delta$-doped layers
• Spontaneous breaking of time reversal symmetry in strongly interacting two dimensional electron layers in silicon and germanium
• All-optical lithography process for contacting atomically-precise devices
• Conductivity and size quantization effects in semiconductor $\delta$-layer systems
• Ab initio theory of the Drude plasma frequency
• Accelerated Lifetime Testing and Analysis of Delta-doped Silicon Test Structures

Cited by in corpus (2)

• Direct integration of atomic precision advanced manufacturing into middle-of-line silicon fabrication
• First principles band structure of interacting phosphorus and boron/aluminum $\delta$-doped layers in silicon