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Electrical properties of high resolution doping structures
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Biswas, Robin Gopal (1992) Electrical properties of high resolution doping structures. PhD thesis, University of Warwick.
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WRAP_Theses_Biswas_1992.pdf - Submitted Version - Requires a PDF viewer. Download (4024Kb) | Preview |
Official URL: http://webcat.warwick.ac.uk/record=b3251663~S15
Abstract
The electrical transport properties and device applications of certain high resolution doping structures in silicon are discussed in this thesis. The promise of enhanced device properties from a high resolution doping structure was envisaged through the use of doping supeelattices. These structures are unobtainable by typical high temperature silicon processing technology and are well suited to fabrication by Molecular Beam Epitaxy. The potential for enhanced mobilities in Boron and Antimony doping superlattices has been investigated by the author. Interpretation of mobility data proved complex due to the number of parallel conduction paths, however, some apparent mobility enhancement was found. Sample fabrication during this work has evolved from the use of crude in house contacts, to microfabricated structures produced by the Edinburgh Microfabrication Facility. This allowed the use of well-defined sample geometries and ohmic contacts to buried doping spikes.
Conductivity and Hall coefficient studies are continued by a study of Si:Sb layers of widths between 5 to SOOnm. A metal-insulator transition is observed as the width of the dopant spike is reduced to Snm. Further measurements on Si:Sb doping spikes of widths 10,20, 80nm at low temperatures 300mK-25K, have been interpreted through the use of weak localisation and electron-electron interaction corrections to the Boltzmann conductivity. Also obtained through magnetoresistance experiments is the first observation of a 2D to 3D transition in the low temperature electrical properties.
The simplest doping profile available in MBE is believed to be one in which the dopant atoms are confined to a few lattice constants, known as a "Delta" layer. This allows the study of two dimensional phenomena in a homoepitaxial system without the presence of an hetero-interface as in the Si-MOSFET. The two dimensional quantisation of the electric subbands in Boron and Antimony delta layers has been investigated via tunnelling spectroscopy. The resultant spectra were found to be consistent with theoretical calculations of subband structure.
Finally, the device application of a delta layer was investigated through the development of the first p-channel boron delta doped FET, which may offer advantages for submicron VLSI technology.
| Item Type: | Thesis (PhD) | ||||
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| Subjects: | Q Science > QC Physics | ||||
| Library of Congress Subject Headings (LCSH): | Silicon -- Electric properties, Solid state physics, Doped semiconductor superlattices | ||||
| Official Date: | August 1992 | ||||
| Dates: |
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| Institution: | University of Warwick | ||||
| Theses Department: | Department of Physics | ||||
| Thesis Type: | PhD | ||||
| Publication Status: | Unpublished | ||||
| Supervisor(s)/Advisor: | Whall, Terry E. | ||||
| Format of File: | |||||
| Extent: | x, 128 leaves : illustrations | ||||
| Language: | eng |
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