Laser-induced modification of n-GaAs below the classical melting thresholdстатья
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Дата последнего поиска статьи во внешних источниках: 27 мая 2015 г.
Аннотация:Laser stimulated processes in Si- and S-doped n-GaAs epitaxial layers are investigated by photoreflectance (PR), time resolved reflectivity (TRR), and photoluminescence (PL). The samples are irradiated with pulses from a ruby laser (20 ns pulse length). It is shown, that a precise in-situ determination of the melting threshold is possible using qualitative changes of PR, while TRR gives a threshold much higher than the melting threshold. A modification of the built-in electrical field (F) is observed in the pre-melting region, while the Si- and S-doped samples show opposite tendencies. A threshold of the PR and PL amplitude modification is determined before the modification of F occurs. It is found, that the laser generated centres of non-irratiative recombination decrease the PR modulation efficiency. The TRR characteristics are explained by the calculated evolution of the temperature distribution.