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Published online by Cambridge University Press: 15 February 2011
In the low temperature (5.5 K) photoluminescent spectra from (Al,Ga)As double heterostructures grown by liquid phase epitaxy (LPE) for laser devices, certain anomalous emission bands higher in energy than the active laye emission but lower in energy than the cladding layer emission are observed. The peak wavelengths and intensities of these anomalous emission bands vary not only from wafer to wafer but also within a given wafer indicating spatial localization of these regions. Photoluminescence measurements on cleaved edges of wafers and on taperetched wafers as well as double-crystal X-ray diffractometry measurements suggest that the anomalous emission bands originate from interfacial regions having different aluminum compositions which are formed between the active and cladding layers presumably as a result of melt carry-over during LPE growth. The integrated photoluminescent intensity of the anomalous emission bands decreases with temperature in the range 75–300 K by nearly two orders of magnitude suggesting the role of some non-radiative process. The spatially localized regions of different aluminum compositions could act as sources and/or sinks for point defects and thus could affect the reliability of devices. Further, their presence would also reflect nonuniformity in the aluminum composition in the active layer.