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Nous presentons ici une methode tres simple de realisation de reseaux d'amplitude de pas sub-micronique sur des films polymeres a base de carbazole deposes sur des substrat de silice. Les reseaux sont fabriques en irradiant avec un faisceau laser a 193 nm un masque de phase place au contact du film. La qualite des reseaux obtenus permet desormais d'envisager la realisation de micro-cavites lasers de type planaire permettant de selectionner une emission laser monomode autour de 400 nm.

Crack-free lattice-matched Al 0.85 In 0.15 N/GaN heterostructures were grown on sapphire substrates with barrier thicknesses up to 100 nm which exhibit very high polarization-induced electron sheet density ( cm −2 ) located at the heterointerface. These layers have been further processed as high electron mobility transistors (HEMTs). Optical characterization of these structures was carried out by photoluminescence and microphotoluminescence (PL) for different biased voltages. The insertion of an InGaN back-barrier unambiguously reveals that spatially direct optical recombinations occur within the AlInN alloy. Since the GaN excitonic bandgap is very sensitive to local temperature changes, the PL technique allows mapping very precisely the actual local temperature distribution in biased HEMT devices. For a gate length of 1.5 m temperatures up to 1130 K were found at a drain-source voltage of 20 V thus indicating the presence of a hot phonon bath.