Momentum‐Space Imaging of Ultra‐Thin Electron Liquids in δ‐Doped Silicon

Abstract

Two‐dimensional dopant layers (δ‐layers) in semiconductors provide the high‐mobility electron liquids (2DELs) needed for nanoscale quantum‐electronic devices. Key parameters such as carrier densities, effective masses, and confinement thicknesses for 2DELs have traditionally been extracted from quantum magnetotransport. In principle, the parameters are immediately readable from the one‐electron spectral function that can be measured by angle‐resolved photoemission spectroscopy (ARPES). Here, buried 2DEL δ‐layers in silicon are measured with soft X‐ray (SX) ARPES to obtain detailed information about their filled conduction bands and extract device‐relevant properties. This study takes advantage of the larger probing depth and photon energy range of SX‐ARPES relative to vacuum ultraviolet (VUV) ARPES to accurately measure the δ‐layer electronic confinement. The measurements are made on ambient‐exposed samples and yield extremely thin (< 1 nm) and dense (≈1014 cm−2) 2DELs. Critically, this method is used to show that δ‐layers of arsenic exhibit better electronic confinement than δ‐layers of phosphorus fabricated under identical conditions.

Adsorption and Thermal Decomposition of Triphenyl Bismuth on Silicon (001)

“…Existing methods for introducing large dopants, like bismuth, typically involve the thermal diffusion of the dopants from a layer of solid material deposited on the surface, , or the kinetic implantation of dopants into the substrate . However, new applications in microphotonics and spintronics have highlighted the need for more precise control over the concentration and location of bismuth atoms in target substrates, as well as a deeper understanding of the quantum mechanical properties of bismuth-doped semiconductors, particularly silicon. − While there has been progress toward the deterministic control of bismuth ion implantation into silicon, such approaches are unlikely to achieve the sub-nanometer precision that has been demonstrated (both in-plane and out-of-plane) using chemical doping methods for dopants, such as phosphorus, arsenic, and boron. − …”

“… 6 − 8 While there has been progress toward the deterministic control of bismuth ion implantation into silicon, 9 such approaches are unlikely to achieve the sub-nanometer precision that has been demonstrated (both in-plane and out-of-plane) using chemical doping methods for dopants, such as phosphorus, arsenic, and boron. 10 − 12 …”