Obiettivo There is an urgent requirement to provide low cost and sensitive systems for pollution sensing and other environmental monitoring applications where trace gases are detected by their fundamental vibrational-rotational absorption bands. This has resulted in a major area of development concerning infrared LEDs and lasers. There has been great progress recently in the development of III-V antimonide-based lasers operating between 2 and 4 micron wavelength and room temperature operation of lasers has been achieved at wavelengths as long as 2.8 micron and to 4.5 micron when cooled to liquid nitrogen temperatures. The goal of this part of the project is to create and investigate semiconductor sources emitting in the 2-10 micron region for pollution monitoring applications and eventually to achieve laser action at wavelengths longer than 4 microns. The InAs/In(As,Sb) superlattices appear to be the most promising materials system for long wavelength laser operation as there is a real prospect that the 'type II' band alignments which are thought to occur can suppress the damaging Auger recombination process which provides a radiationless path for recombination and is normally very strong in narrow-gap semiconductors. This is the most important single factor which has prevented laser operation at longer wavelength to date.The second goal of the project is to study the optical and electrical properties of the quasi-two-dimensional electron-hole plasma. GaSb-InAs heterojunctions or superlattices in which InAs forms quantum wells and the GaSb barriers will be used for these investigations. This system has a semimetallic band alignment so that intrinsically there are equal numbers of electrons and holes. There has been considerable speculation for some time that a narrow- or zero-gap semiconductor system could lead to the formation of stable excitonic states at low temperatures. Experimental evidence for such states has been lacking until very recently when a US group reported far-infrared magneto-optical experiments which showed the presence of an additional line approximately 3 meV above the cyclotron resonance line in a number of InAs/(Ga,Al)Sb quantum wells. This new line disappeared with increasing temperature as would be expected for an excitonic phase. Programma(i) IC-INTAS - International Association for the promotion of cooperation with scientists from the independent states of the former Soviet Union (INTAS), 1993- Argomento(i) 15 - Condensed Matter Physics Invito a presentare proposte Data not available Meccanismo di finanziamento Data not available Coordinatore Imperial College of Science, Technology and Medicine Contributo UE Nessun dato Indirizzo Blackett Laboratory Prince Consort Road SW7 2BZ London Regno Unito Mostra sulla mappa Costo totale Nessun dato Partecipanti (4) Classifica in ordine alfabetico Classifica per Contributo UE Espandi tutto Riduci tutto Centre National de la Recherche Scientifique Francia Contributo UE Nessun dato Indirizzo 31077 Toulouse Mostra sulla mappa Costo totale Nessun dato Russian Academy of Sciences Russia Contributo UE Nessun dato Indirizzo 194021 St. Petersburg Mostra sulla mappa Costo totale Nessun dato Russian Academy of Sciences Russia Contributo UE Nessun dato Indirizzo 194021 St. Petersburg Mostra sulla mappa Costo totale Nessun dato Russian Academy of Sciences Russia Contributo UE Nessun dato Indirizzo 142092 Troitsk, Moscow Region Mostra sulla mappa Costo totale Nessun dato
