Dresden 2014 – scientific programme

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O: Fachverband Oberflächenphysik

O 72: Competition for the Gerhard Ertl Young Investigator Award

O 72.3: Talk

Thursday, April 3, 2014, 11:30–12:00, PHY C 213

Digging up the band structure of buried layers — •Jill Miwa¹, Philip Hofmann¹, Oliver Warschkow², Damien Carter³, Nigel Marks³, Michelle Simmons⁴, and Justin Wells⁵ — ¹Aarhus University, Denmark — ²University of Sydney, Australia — ³Curtin University, Australia — ⁴UNSW, Australia — ⁵NTNU, Norway

Atomically precise dopant placement opens up an exciting new arena for exploring complex valley physics in novel materials and quantum electronic devices. Atomic scale devices derived from phosphorus δ-layers in silicon have been recently demonstrated, including a single-atom transistor. A δ-layer is formed several nanometers beneath the surface of silicon because of a one-atom-thick plane of phosphorus dopants which are placed there. The local but strong doping leads to confined 2D electron states, separated by an energy referred to as valley splitting. The magnitude of the valley splitting has implications for critical device properties. Hitherto only indirect information on the electronic structure of the 2D states and valley splitting was available and a reliance on calculations has been necessary. We directly measure the band structure of a buried δ-layer using ARPES. Although the δ-layer is deeply buried, relative to the photoelectron mean free path, photoemission is still possible at very low kinetic energies, or when a resonant enhancement is invoked. By engineering a favourable surface Umklapp process, we can resolve the δ-layer states and measure a valley splitting of 132meV, which falls centrally within reported calculated values. Electronic properties, such as valley splitting, are central in understanding δ-layers and their use in atomic-scale devices.