Eoin O'Sullivan

Developing a framework for mapping industrial emergence

The industrial landscape is becoming increasingly complex and dynamic, with innovative technologies stimulating the emergence of new industries and business models. This paper presents a preliminary framework for mapping industrial emergence, based on roadmapping principles, in order to understand the nature and characteristics of such phenomena. The focus at this stage is on historical examples of industrial emergence, with the preliminary framework based on observations from 20 ‘quick scan’ maps, one of which is used to illustrate the framework. The learning from these historical cases, combined with further industrial consultation and literature review, will be used to develop practical methods for strategy and policy application. The paper concludes by summarising key learning points and further work needed to achieve these outcomes.

Electron transport in modulation-doped GaAs v-groove quantum wires

Abstract We report the growth of modulation-doped GaAs/Al x Ga 1− x As v-groove quantum wires and structural, electrical and optical investigations of their electronic states and transport properties. By using alternative group III precursors on partially SiO 2 masked pre-patterned GaAs substrates, samples have been fabricated which permit electrical measurements of single isolated wire structures without the need for additional electron-beam lithography. Magneto-transport was measured as a function of tilt angle of the incident magnetic field to identify the formation of low-dimensional electron gases in different parts of the structure. Photoluminescence investigations reveal 1D and 2D confined states which show different carrier heating when electric fields are applied along the wire structure.

The "Celtic Tiger" and a Knowledge Economy.

Over the last two decades, Ireland has proactively marketed its educated workforce, its favourable corporate tax rates, membership of the European common market, and other advantages, to multinational technology corporations. The resulting foreign direct investment in high-tech manufacturing operations has driven a booming Irish economy that has come to be characterized as the ‘Celtic Tiger’. Today, however, Ireland is looking to the research and development sector to drive future growth. Competition from low-wage economies, such as those of Eastern Europe, India and China, threatens Irelands position as a low-cost, high-tech manufacturing base. Across government, industry and the higher education sectors, Ireland is now focused on fashioning an ecosystem of research and innovation that can guarantee its continued prosperity.

Fermi-edge singularities in the photoluminescence spectrum of modulation-doped GaAs v-groove quantum wires

Abstract We report the observation of strong Fermi-edge singularities in the photoluminescence spectrum of strongly-confined, modulation-doped GaAs v-groove quantum wires. The behaviour of the singularity has been investigated at high excitation intensity, and both lattice and electrical heating. The latter produces a strong reduction of the singularity due to Fermi surface smearing, whereas, increased photoexcitation produces complex electron–hole correlation effects.

Hot Carrier Relaxation by Extreme Electron–LO Phonon Scattering in GaN

Hot carrier relaxation has been investigated in GaN using non-resonant femtosecond excitation where electrons are excited above and below the LO phonon energy. We observe remarkably rapid electron relaxation; the electron distribution is non-thermal, with a “cut-off” occurring near ELO. In a preliminary Monte Carlo study we have simulations which reproduce the major experimental observations, confirming the development of a non-thermal electron distribution near ELO due to the strong electron–LO phonon interaction. Hot phonon effects are pronounced at high carrier densities.

Direct Observation of Femtosecond Intervalley Scattering in GaSb: Electron–Phonon Scattering and Continuum Coherent Transients

Femtosecond Γ–L intervalley electron scattering has been observed in bulk GaSb and GaSb/AlSb quantum wells using time-resolved differential transmission and Raman spectroscopy. The reverse process is found to occur on a significantly longer time scale due to long-lived Γ state occupancy. The results are in good agreement with Monte Carlo simulations. GaSb quantum wells display an additional ultrafast induced absorption when continuum states are excited which may arise from electron–hole coherence effects.

Hot phonons and non-thermal carrier states in GaN

Abstract Non-thermal carrier states at early times are studied using femtosecond pump–probe spectroscopy in GaN. After the residual chirp on the continuum probe is removed, the normalized difference spectra (NDS) for different probe energies are synchronized, recovering the full time resolution of our laser pulse (120 fs ) . Our Monte-Carlo simulation agree well with the unchirped NDS spectrum, which shows the development of the carrier distribution at early times, where phonon satellites are seen, together with a strong non-thermal electron distribution in the region of the LO-phonon energy arising from the remarkably strong electron–LO phonon interaction. Employing a new technique which involves the integration of the normalized NDS multiplied by the corresponding energy, a measure of the mean energy of the carriers in non-thermal states is obtained. By comparing the time-dependent energy loss with the theoretical energy loss rate, we estimate the effective temperature of the phonon modes as well as the population of phonons. Our Monte-Carlo model agrees well with this data, and confirms the dominance of hot phonon effects at early times.

Fermi-edge singularities in the photoluminescence and magneto-optical spectra of modulation-doped v-groove quantum wires

Abstract We report the obervation of a strong Fermi-edge singularity in the photoluminescence spectrum of a degenerate one-dimensional electron system in modulation-doped GaAs/GaAlAs v-groove quantum wires. The singularity is pronounced due to 1D subband mixing, which is further enhanced by an applied transverse magnetic field.

Ultrafast optical response and inter-valley scattering in GaSb/AlSb quantum wells

Abstract We report femtosecond time-resolved differential transmission measurements of GaSb/AlSb quantum wells which reveal direct evidence of electron Γ–L intervalley scattering. Raman measurements of non-equilibrium phonons generated by intra-Γ electron relaxation yield a complementary picture of the carrier dynamics, confirming the measured intervalley scattering rate.

The evolving role of standardisation in technological innovation: the case of photovoltaics

Despite the increasing awareness on the importance of standards in supporting technological innovation, there are limited understanding and empirical evidence on various roles of standards in supporting innovation activities and how they evolve over time, due to the complexity involved in innovation and standardisation. The current research carefully explores the evolving role of standardisation, through the historical study of standardisation in photovoltaics technology. Analysing archival documents and expert interviews both quantitatively and qualitatively, it is observed that various types of standards played different roles and functions to support different technological activities across its innovation journey. The study is expected to broaden the evidence base to inform standards organisations and policymakers in developing standardisation strategies to support technological innovation more effectively.