Momentum space imaging of ultra-thin electron liquids in δ-doped silicon

Dataset: SX-ARPES raw data, processed data and the codes used for analysing and data fitting our work at doi/10.1002/advs.202302101 are all available here. The theoretical mdelling is also avaiable. 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 (ARPES). Here, we measure buried 2DEL δ-layers in silicon with soft X-ray (SX) ARPES to obtain detailed information about their filled conduction bands and extract device-relevant properties. We take 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. Our measurements are made on ambient-exposed samples and yield extremely thin (< 1 nm) and dense (~1014 cm-2) 2DELs. Critically, we use this method to show that δ-layers of arsenic exhibit better electronic confinement than δ-layers of phosphorus fabricated under identical conditions.