Determining the Electronic Confinement of a Subsurface Metallic State

作者：Mazzola Federico; Edmonds Mark T; Hoydalsvik Kristin; Carter Damien John; Marks Nigel A; Cowie Bruce C C; Thomsen Lars; Miwa Jill; Simmons Michelle Yvonne; Wells Justin W^*

来源：ACS Nano, 2014, 8(10): 10223-10228.

DOI：10.1021/nn5045239

• Si:P delta-layers
• photoemission
• 2D confinement
• quantum computation

Dopant profiles in semiconductors are important for understanding nanoscale electronics. Highly conductive and extremely confined phosphorus doping profiles in silicon, known as Si:P d-layers, are of particular interest for quantum computer applications, yet a quantitative measure of their electronic profile has been lacking. Using resonantly enhanced photoemission spectroscopy, we reveal the real-space breadth of the Si:P d-layer occupied states and gain a rare view into the nature of the confined orbitals. We find that the occupied valley-split states of the d-layer, the so-called 1 Gamma and 2 Gamma, are exceptionally confined with an electronic profile of a mere 0.40 to 0.52 nm at full width at half-maximum, a result that is in excellent agreement with density functional theory calculations. Furthermore, the bulk-like Si 3pz orbital from which the occupied states are derived is sufficiently confined to lose most of its pz-like character, explaining the strikingly large valley splitting observed for the 1 Gamma and 2 Gamma states.

• 出版日期2014-10