Obiettivo In the foreseeable future most microelectronic semiconductor materials for IT devices will be produced by thin-film growth techniques under vacuum conditions and from gas, liquid and solid processes. Perfecting the thin-layer interface is very important in making possible higher quality device performance. This Action has developed a new field of surface and interface characterisation called "epioptics". This has submonolayer resolution and is accurate enough to distinguish single atomic layers of crystals. Epioptics, using light as both probe and signal, enables growth to be characterised in situ and, uniquely, in all growth environments.New techniques for determining the properties of materials used in information technology devices have been developed. Light is used both as a probe and a signal (epioptics) and extremely high resolution can be obtained. In contrast to existing techniques, epioptics can be used in situ, while growing the crystals, in all the environments employed for this purpose. Applying epioptics to various processes provides new insights into the growth mechanisms involved, thus increasing yield and quality.The project has shown that light can indeed be used to characterize surface and interface structure, with submonolayer resolution, due to advances in instrumental design, symmetry rules which forbid bulk response, and the discovery of strong, resonant surface contributions at particular wavelengths of light. Carefully chosen systems, which have been thoroughly characterized by conventional surface probes, have been used to establish the credibility of the new techniques from both an experimental and theoretical viewpoint.Reflection anisotropy spectroscopy (RAS) has been shown to be the most promising all optical technique for real time growth monitoring on commercial reactors. At the end of the project the growth of indium arsenic on gallium arsenic in an molecular beam epitaxy (MBE) growth reactor was monitored layer by layer, in situ, in real time. An additional spin off from the project was that RAS was show to provide a quick and easy method for checking silicon wafer orientation.APPROACH AND METHODS Epitaxial layers, including As, Ga, GaAs and Sb were grown on silicon substrates by molecular beam epitaxy (MBE), and As and GaAs by photo-enhanced metal organic vapour phase epitaxy (photo-MOVPE). The material was extensively characterised using conventional techniques. A number of purely optical techniques providing complementary information were then used to investigate and characterise the surface and interface of the material with submonolayer resolution in situ. The techniques used were polarisation-dependent reflectivity (spectroscopic ellipsometry, reflection difference spectroscopy and reflection anisotropy), Raman spectroscopy, laser-induced fluorescence and optical second harmonic generation. A strong cooperative theoretical effort underpinned the experimental work. The Action involved experts in the field of epitaxial growth, materials characterisation by optical techniques, and the theory of the optical response of interfaces. PROGRESS AND RESULTS This Action has shown that light can indeed be used to characterise surface and interface structure, with sub-monolayer resolution, due to advances in instrumental design, symmetry rules which forbid bulk response, and the discovery of strong, resonant surface contributions at particular wavelengths of light. Carefully chosen systems, which have been thoroughly characterised by conventional surface probes, have been used to establish the credibility of the new techniques from both an experimental and theoretical viewpoint. Reflection anisotropy spectroscopy (RAS) has been shown to be the most promising all-optical technique for real-time growth monitorig on commercial reactors. At the end of the Action the growth of InAs on GaAs(100) in an MBE growth reactor was monitored layer-by-layer, in situ, in real time. An additional spin-off from the Action was that RAS was shown to provide a quick and easy method for checking Si wafer orientation (Siemens-TU Berlin joint patent P4127704.4). POTENTIAL This Action has demonstrated the feasibility of using optical probes to monitor growth of thin-film IT materials with submonolayer resolution in situ and under all growth conditions. Implementation of these new characterisation techniques should result inimproved materials and higher yields for the fabrication of future IT semiconductor devices. Campo scientifico natural scienceschemical sciencesinorganic chemistrypost-transition metalsnatural sciencesphysical scienceselectromagnetism and electronicssemiconductivitynatural scienceschemical sciencesinorganic chemistrymetalloidsnatural sciencesphysical sciencesopticsspectroscopy Programma(i) FP2-ESPRIT 2 - European strategic programme (EEC) for research and development in information technologies (ESPRIT), 1987-1992 Argomento(i) Data not available Invito a presentare proposte Data not available Meccanismo di finanziamento Data not available Coordinatore University of Dublin Contributo UE Nessun dato Indirizzo Trinity College Dublin 2 Irlanda Mostra sulla mappa Costo totale Nessun dato Partecipanti (6) Classifica in ordine alfabetico Classifica per Contributo UE Espandi tutto Riduci tutto Defence Research Agency (DRA) Regno Unito Contributo UE Nessun dato Indirizzo St Andrews Road WR14 3PS Malvern Mostra sulla mappa Costo totale Nessun dato TECHNISCHE UNIVERSITÄT BERLIN Germania Contributo UE Nessun dato Indirizzo STRAßE DES 17 JUNI 135 10623 BERLIN Mostra sulla mappa Costo totale Nessun dato THE UNIVERSITY OF LIVERPOOL Regno Unito Contributo UE Nessun dato Indirizzo Oxford Street L69 7ZE LIVERPOOL Mostra sulla mappa Costo totale Nessun dato University of Wales, Cardiff Regno Unito Contributo UE Nessun dato Indirizzo CF1 1XL CARDIFF Mostra sulla mappa Costo totale Nessun dato Università degli Studi di Messina Italia Contributo UE Nessun dato Indirizzo Salita Sperone 31 98166 Sant'Agata di Messina Mostra sulla mappa Costo totale Nessun dato Università degli Studi di Roma Tor Vergata Italia Contributo UE Nessun dato Indirizzo Via Orazio Raimondo 1 00173 Roma Mostra sulla mappa Costo totale Nessun dato