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The thesis examines the Welsh economy from the latter decades of the 20th century to the present day. In comparison with other UK and EU regions, Wales’ economic performance has been disappointing. This raises the question of whether the economic strategy of attracting foreign direct investors has been appropriate. The author undertook a SWOT analysis of the Welsh economy in the hope of identifying policies that could build upon Wales’ strengths, eliminate weaknesses and exploit opportunities. This was undertaken by applying M.E. Porter’s framework of the “economic diamond of growth” to the economy. Results showed that the “diamond” within Wales is weak. Moreover, since the economy is dominated by the manufacturing, and the public sectors, any future improvement has to be sought from the manufacturing sector. The thesis argues that Wales, without a capital legacy from its industrial past, still finds itself reliant of foreign owned capital. However, multinational enterprises rely on efficient supply chains as a means of maintaining competitive positions; these in turn, are influenced by clustering activities. By developing the Nilssen model on generic types of production, the author argues that Wales needs to focus on the production of high value added products requiring R&D, skilled labour, and are sold in high income markets. Detailed market research undertaken by the author shows that Wales has two strong, and two embryonic clusters, automotive and electronics, and opto electronics and biotechnology respectively, that need nurturing. By applying research data to the Kearney prognosis model, the authors is able to suggest which automotive branch plants are likely to remain viable in the immediate future. This could be a potentially useful accessory to a grant-giving agency. This thesis concludes by outlining a number of recommendations aimed at improving Welsh economic performance.

In this thesis, calculations of Auger recombination rates in semiconductor quantum wells are presented. Chapter One introduces Auger recombination, and the reasons for studying the Auger process are explained. Basically, Auger recombination is a non- radiative recombination mechanism that becomes more important as the carrier density increases and the bandgap decreases. In direct gap semiconductors, the Auger process has an activation energy, and the resulting highly temperature dependent Auger process is thought to be a possible cause of the high temperature sensitivity of long wavelength semiconductor lasers that are being considered for use as sources in optical fibre communications systems. In Chapter Two, an expression is derived for the CHSH Auger recombination rate in a quantum well (QW) heterostructure. The possible Auger processes in a QW are discussed as are the differences between Auger recombination in a QW and in bulk semiconductors, and the magnitudes of QW and bulk Auger rates are compared. In Chapter Three, the theory of Auger recombination is extended to the case of a quantum well wire (QWW), a semiconductor structure in which carriers are free to move in one direction only. It is found that there are no significant physical differences between Auger recombination in a QW and in a QWW. The ratio of QW and QWW Auger rates is evaluated. Numerical results for Auger transition rates in 1.3µm and 1.55µm In- GaAsP/InP QWs and QWWs are presented in Chapter Four, and comparison with experimental values is made. In particular, the result found in Chapter Two, that, under certain conditions, the Auger rates in the QW and the bulk are approximately the same is found to agree with experimental results from the literature. The derivation of the CHSH Auger transition rates in QWs and QWWs that was presented in Chapters Two and Three required a number of approximations concerning the carrier statistics and the semiconductor bandstructure. In Chapter Five, these approximations are examined, and, although it is found that the use of non-degenerate carrier statistics is reasonably accurate, the assumption of parabolic energy bands can lead to overestimates of .the Auger transition rates. The first five chapters constitute the first part of the thesis, concerning Auger recombination in low-dimensional semiconductor structures. In the second part of the thesis, the realistic bandstructure of low-dimensional semi conductor structures, such as superlattices, is examined. The method used is described in Chapter Six, and is based on an empirical pseudopotential method. Results for the GaAs/AlAs superlattice are presented in Chapter Seven.