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Strain distribution in GaN hexagons measured by Raman spectroscopy
Seitz, R.; Monteiro, Teresa; Pereira, Maria Estela; Di Forte-Poisson, M.Epitaxial growth of GaN layers normally starts in a three-dimensional growth mode at nucleation sites. Growth islands are formed which coalesce when a certain layer thickness is achieved. In our samples these islands show hexagonal structure and in some cases a flat surface plane perpendicular to the (0001) growth direction. We studied these hexagons by spatially resolved Raman spectroscopy. Raman spectroscopy ...
Time resolved photoluminescence of cubic Mg doped GaN
Seitz, R.; Gaspar, C.; Monteiro, T.; Pereira, E.; Schoettker, B.; Frey, T.; As, D.J.; Schikora, D.; Lischka, K.Mg doped cubic GaN layers were studied by steady state and time resolved photoluminescence. The blue emission due to Mg doping can be decomposed in three bands. The decay curves and the spectral shift with time delays indicates donor-acceptor pair behaviour. This can be confirmed by excitation density dependent measurements. Furthermore temperature dependent analysis shows that the three emissions have one impu...
Photoluminescence between 3.36 eV and 3.41 eV from GaN epitaxial layers
Seitz, R.; Gaspar, C.; Monteiro, T.; Pereira, E.; Poisson, M.A.; Beaumont, B.In this study, an attempt was made to analyze the luminescence between 3.36 eV and 3.41 eV of nid hexagonal GaN samples grown on sapphire. Sample dependent emission lines with no donor-accetor pair (DAP) behavior were found. Based on the data, different kinds of recombination processes in the same spectral region were identified.
Temperature behaviour of the yellow emission in GaN
Seitz, R.; Gaspar, C.; Monteiro, T.; Pereira, E.; Leroux, M.; Beaumont, B.; Gibart, P.Even in good quality undoped GaN samples, as assessed by the intense excitonic emission, the yellow band is present. This band has been attributed either to a shallow donor to deep double donor pair recombination [1], to a deep donor to a shallow acceptor [2] or to a shallow donor and a deep state [3]. However, its origin is not yet clear. We present data on time resolved spectroscopy compared with steady state...
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