Photoluminescence microscopy imaging of tensile strained In 1−x Ga x As y P 1−y / InP quantum wells grown by low-pressure metalorganic vapor phase epitaxy Substitution of As atoms by P ones during the growth of GaAs/Ga 0.51 In 0.49 P quantum wells ͑QWs͒ is investigated by photoluminescence ͑PL͒ as a function of temperature and under hydrostatic pressure. We have studied a series of samples, grown by chemical beam epitaxy, in which this substitution is achieved by changing the exposure time of GaAs surface to cracked PH 3 . The emision lines related to the QWs are blueshifted when the time of exposure to PH 3 increases; this is due to the formation of Ga͑As,P͒ monolayers by P-As exchange. Two samples are examined by PL under hydrostatic pressure at 5 K. The ⌫ -X crossover, which corresponds to the transfer of electrons from the ⌫ conduction band states of the QWs to X valley states of the Ga͑As,P͒ interfacial layers occurs at 3.2 GPa for the sample grown with the shortest exposure time ͑5 s͒. In contrast, it occurs at 2.4 GPa for the the sample with the longest exposure time ͑35 s͒. The data obtained by PL under pressure give evidence of the formation of a GaP-rich layer up to 2 monolayers thick at the Ga 0.51 In 0.49 P on GaAs interface. Calculations allow us to estimate the modifications of the P concentration profile among the samples.

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