Details of Grant 

EPSRC Reference:	EP/C009738/1
Title:	Instrument to probe the electronic and structural properties of impurities, defects and nanostructures in semiconductor materials and devices
Principal Investigator:	Peaker, Professor AR
Other Investigators:	Song, Professor AM Hawkins, Dr I
Researcher Co-Investigators:
Project Partners:	University of Arhus
Department:	Electrical and Electronic Engineering
Organisation:	University of Manchester, The
Scheme:	Standard Research (Pre-FEC)
Starts:	04 April 2005	Ends:	03 October 2008	Value (£):	689,919
EPSRC Research Topic Classifications:	Instrumentation Eng. & Dev. Materials Characterisation
EPSRC Industrial Sector Classifications:	Electronics
Related Grants:
Panel History:
Summary on Grant Application Form
Measuring the small concentrations of impurities that are crucial to the performance of semiconductors is very difficult. The successful incorporation of dopant impurities to introduce holes and electrons (roughly 1 part in 100 million) into small volumes of material (of the order of 100nm cube in production silicon devices) is central to the whole science and technology of semiconductors. Even smaller quantities of some inadvertent impurities (eg iron at 1 part in a million million) can adversely affect performance. A few chemical analysis techniques (eg secondary ion mass spectrometry, SIMS) are capable of quantifying and depth profiling most of the common dopants at concentrations around 1 part in 100 million (usually in large area test structures) but cannot detect the inadvertent impurities or equally importantly cannot detect intrinsic defects (vacancies and self interstitials). These can be very significant in semiconductor technology. A further complication is that in a semiconductor it is not just the chemical species that is important but its precise site in the semiconductor lattice. For example, in silicon, oxygen at an interstitial site is generally beneficial while oxygen paired with a vacancy can be detrimental. The aim of this research is to develop and build a prototype instrument which will determine the absolute concentration and properties of impurities and defects in a small volume of semiconductor material or a device structure by measuring the interaction of the impurity or defect with the semiconductor lattice. It does this by quantifying the binding energy of holes and electrons to the impurity or defect. The theoretical basis for this was expounded over fifty years ago and, in recent years, has developed rapidly resulting in a good (although still far from perfect) understanding of the physics behind this measurement. A number of simple commercial instruments have appeared on the market based on this principle (including one originating from the investigators of this contract) and have to a limited extent satisfied the immediate needs of the industry. However, all have failed to meet the requirements of researchers in the field because of the inability to discriminate between electronically similar defects and the inability to provide detailed electronic, physical or chemical information. The new instrument builds on work done by the Manchester group in which shifts in the carrier binding energy have been measured under the influence of external perturbations (eg stress). In order to observe this high resolution is required (~ 2 mili-electron-volts). These perturbations of the binding energy are then be used to determine the electronic and physical structure of the impurities and defects and under appropriate conditions observe their reconfiguration or motion in the lattice. This amount of energy which needs to be measured represents little more than the thermal broadening at typical measurement temperatures (around 100K) which means there must be no instrumental broadening. No commercial instrument exists which can do this but a proof of principle system originating from Manchester has demonstrated the feasibility of both the instrument and aspects of the research. The instrument will contribute to a wide range of research well represented in the UK and European scientific communities. In particular it will be used within this project to achieve a fundamental understanding of the behaviour of trace impurities and lattice defects in very small structures and is expected to be a key tool not only in fundamental research in relation to diffusion, defects and strain in semiconductor devices. It will also be of significance in the development of novel semiconductor nanostructures and commercial nanoscale devices.
Key Findings
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Organisation Website:	http://www.man.ac.uk