Catálogo de publicaciones - libros

We present an overall impression of the present state of knowledge on the formation, via a modified Stranski-Krastanov growth mode, of InAs quantum dots (QDs) on GaAs substrates. We will begin with the substrate orientation and surface reconstruction specificity of QD formation, which demonstrates that QDs are the exception rather than the rule in this system, with the implication that a second process, in addition to strain relaxation, is involved in the driving force. We then discuss the formation of an alloy wetting layer, and although it may not be unique to growth on the GaAs(001) c(4 × 4) surface, it is very much more marked than on any other. This is an important effect, in that QD formation is effectively limited to the same surface reconstruction. The next stage involves this formation process and we will review the experimental evidence, including dot composition, size (volume) distribution (including scaling behaviour), and two-dimensional to three-dimensional transition effects, with some comments on possible experimental artefacts in this area. We conclude with some comments on QD shape, based mainly on reflection high energy electron diffraction (RHEED) results, but including a comparison with results from transmission electron microscopy (TEM) and scanning tunnelling microscopy (STM).

We present an overall impression of the present state of knowledge on the formation, via a modified Stranski-Krastanov growth mode, of InAs quantum dots (QDs) on GaAs substrates. We will begin with the substrate orientation and surface reconstruction specificity of QD formation, which demonstrates that QDs are the exception rather than the rule in this system, with the implication that a second process, in addition to strain relaxation, is involved in the driving force. We then discuss the formation of an alloy wetting layer, and although it may not be unique to growth on the GaAs(001) c(4 × 4) surface, it is very much more marked than on any other. This is an important effect, in that QD formation is effectively limited to the same surface reconstruction. The next stage involves this formation process and we will review the experimental evidence, including dot composition, size (volume) distribution (including scaling behaviour), and two-dimensional to three-dimensional transition effects, with some comments on possible experimental artefacts in this area. We conclude with some comments on QD shape, based mainly on reflection high energy electron diffraction (RHEED) results, but including a comparison with results from transmission electron microscopy (TEM) and scanning tunnelling microscopy (STM).

We present an overall impression of the present state of knowledge on the formation, via a modified Stranski-Krastanov growth mode, of InAs quantum dots (QDs) on GaAs substrates. We will begin with the substrate orientation and surface reconstruction specificity of QD formation, which demonstrates that QDs are the exception rather than the rule in this system, with the implication that a second process, in addition to strain relaxation, is involved in the driving force. We then discuss the formation of an alloy wetting layer, and although it may not be unique to growth on the GaAs(001) c(4 × 4) surface, it is very much more marked than on any other. This is an important effect, in that QD formation is effectively limited to the same surface reconstruction. The next stage involves this formation process and we will review the experimental evidence, including dot composition, size (volume) distribution (including scaling behaviour), and two-dimensional to three-dimensional transition effects, with some comments on possible experimental artefacts in this area. We conclude with some comments on QD shape, based mainly on reflection high energy electron diffraction (RHEED) results, but including a comparison with results from transmission electron microscopy (TEM) and scanning tunnelling microscopy (STM).

The paper studies the patterns of volatility in firm growth rates and stock prices during the early phase of the life-cycle of an old economy industry, the US automobile industry from 1900–1930, and a new economy industry, the US PC industry from 1974–2000. In both industries, firm growth rates are more volatile in the period in which innovation is the most “radical”. This is also the period in which stock prices are more volatile. The comparison sheds light on the co-evolution of industrial and financial volatility and the relationship between this co-evolution and mechanisms of Schumpetarian creative destruction. Results provide insight into the debate on whether the statistical behavior of firm growth rates is well represented by Gibrat’s Law.

In many industries, production resides in a small number of highly concentrated regions; for example, several high tech industries cluster in Silicon Valley. Explanations for this phenomenon have focused on how the co-location of firms in an industry might increase the efficiency of production. In contrast, this article argues that industries cluster because entrepreneurs find it difficult to access the information and resources they require when they reside far from the sources of these valuable inputs. Since existing firms often represent the largest pools of these important factors, the current geographic distribution of production places important constraints on entrepreneurial activity. As a result, new foundings tend to arise in the same areas as existing ones, and hence reproduce the industrial geography. In support of this thesis, the article reviews empirical evidence from the shoe manufacturing and biotechnology industries.

We propose a Nelson-Winter model with an explicitly defined landscape to study the formation of high-tech industrial clusters such as those in Silicon Valley. The existing literature treats clusters as the result of location choices and focuses on how firms may benefit from locating in a cluster. We deviate from this tradition by emphasizing that high-tech industrial clusters are characterized by concentrated entrepreneurship. We argue that the emergence of clusters can be explained by the social effect through which the appearance of one or a few entrepreneurs inspire many followers locally. Agent-based simulation is employed to show the dynamics of the model. Data from the simulation and the properties of the model are discussed in light of empirical regularities. Variations of the model are simulated to study policies that are favorable to the high-tech economy.

Five problems are addressed: (1) the role of competent actors in the venture capital and exit markets supporting the industrialization of winning technologies in small innovative firms, (2) the competence of the large firm to integrate large-scale operational efficiency with small-scale innovative capability through distributed development work and integrated production and (3) the importance of viable markets for strategic acquisitions, both in making this possible and in allowing a flexible choice for the small firm between growing aggressively on its own through own acquisitions, or being acquired strategically itself. We (4) find that the less developed markets in continental Europe may be a disadvantage compared to the US in ushering in a future New Economy. We finally (5) discuss what becomes of the Coasian theory of the firm when production is constantly outsourced in, or insourced from the market as the relative efficiency of coordination through management and over the market changes. One logical consequence is that the costs of business mistakes will have to be included in transaction costs.

During the long economic upswing of the 1980s and 1990s, the successful commercialization of new technology went together with the appearance of new financial vehicles, new organizational forms, and new practices promoting and mediating the transfer of the new technology from lab to market. They included business incubators, technology parks, venture capitalist firms, operators specializing in mergers and acquisitions, venture funds, and initial public offerings in the stock market. Commercialization-facilitating organizations and practices like these (here called “commercialization facilitators”) are themselves born by dynamic processes in a capitalist economy that can be analyzed in Schumpeterian terms. We discuss at some length a unique university-based institution that has an impressive track record of creating and operating new facilitating models: the IC Institute (Innovation, Creativity and Capital) of the University of Texas. During a twenty-five year period, IC came to be instrumental in the conversion of the local economy to the high tech age. The Institute’s activities span the range of the technology transfer and commercialization process, from the development and dissemination of new knowledge to the actual running of business incubators. We identify the IC Institute as a “second order” facilitator and discuss its possible global evolution into a “third order” facilitator.

The New Economy is closely associated with computing & communications technology, notably the Internet. We discuss property rights to, and trade in, the difficult-to-define intangible assets increasingly dominating the New Economy, and the possibility of under-investment in these assets. For a realistic analysis we introduce a Schumpeterian market environment (the ). prevail when the rights to , and intangible assets cannot be fully exercised. The trade-off between the benefits of open access on the Internet, and the incentive effects of strengthened property rights, depend both on the particular strategy a firm employs to secure property rights, and the protection offered by law. property rights can be strengthened if the originator can find innovative ways to charge for the intangible assets. The extreme complexity of the New Economy and the large number of possible innovative private contract arrangements make it more important to facilitate the use and enforcement of private individualized contracts to protect intellectual property than to rely only on standard patent and copyright law. is one proposed solution. Current patent legislation in the US has led to costly litigation processes weakening the position of small firms and individuals in patent disputes. The property rights of such firms and individuals could be strengthened with insurance or arbitration procedures.

The “dotcom boom” and subsequent collapse raises issues as to the nature of capital and the relationship between capital and investment. Capital in conventional finance, based on the Fisher-Hirshleifer analysis, is defined as postponed consumption and investment is defined as a trade-off between consumption now and in the future. This paper argues that a more satisfactory explanation of the relationship between investment and capital was developed by the Austrian economist Böhm-Bawerk, who identified capital goods as separate from consumption goods, and where the passage of time is fundamental to the accumulation of capital. Such a process assumes risk rather than uncertainty, and does not capture the essence of Schumpeterian investment.