부산대학교 도서관

With the recent advances of deterministic atomic-scale patterning of phosphorous and arsenic on silicon, proposed architectures for silicon-based quantum computation are close to being realized. For future scalable devices, the role of atomically abrupt `delta' layer interfaces will be critical to device operation, so a further understanding is required in the two-dimensional (2D) physics involved. This thesis discusses a broad range of characterization methods that are employed to measure the properties of buried, 2D dopant δ-layers in silicon, whilst also developing a new method of resistless extreme ultra-violet (EUV) lithography on hydrogen passivated silicon. The first results chapter discusses the optimal method for quantifying secondary ion mass spectrometry (SIMS) depth profile measurements and the progress made towards standardizing scanning tunnelling microscopy (STM) based hydrogen desorption lithography at UCL. We then demonstrate that photoemission electron microscopy (PEEM) can be used to laterally image atomically-thin phosphorous and arsenic δ-layer patterns buried in silicon, with a minimum feature size of 25 nm. The second results chapter establishes the use of synchrotron radiation in the EUV range to desorb hydrogen on the Si(001)-(2x1):H surface. Using x-ray photoelectron spectroscopy (XPS) and STM data, we develop a method to quantify the surface dangling bond density, where the data reveals that the desorption mechanism is associated with valence band excitations mediated via secondary electrons. The third results chapter shows the first soft x-ray angle-resolved photoemission spectroscopy (SX-ARPES) measurements of phosphorous and arsenic δ-layers in silicon. We demonstrate that by measuring the kz extension of the out-of-plane valleys, this offers by far the most sensitive probe of electronic two-dimensionality of silicon δ-layers yet achieved. We found that arsenic δ-layers exhibit considerably more electronic two-dimensionality than their phosphorus counterparts and also measure the absolute charge densities, relative occupancies and donor sub-band minima of the δ-layers, which yield an excellent corroboration with theoretical predictions.