Investigation of (AlGa)As/GaAs quantum wells by optical and phototransport measurements

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Abstract
An optical and phototransport characterization of (AlGa)As/GaAs multi‐quantum‐well (MQW) structures grown by molecular beam epitaxy (MBE) is reported. Photovoltage, photoluminescence, and optical transmission spectra are studied on p‐i‐n photodiodes in which the intrinsic (nominally undoped) region contains the wells. The thickness of GaAs and (AlGa)As layers is in the range 8 to 11 and 12 to 17 nm, respectively. The Al x‐molar fraction is in the interval 0.25 to 0.30. In the photovoltage spectra transitions between the fundamental and also the first excited state of electron and hole subbands in the quantum wells are observed. Agreement is found between these spectra and the results of luminescence and transmission measurements. Theoretical calculation fits the temperature dependence of the peaks in the spectra; it is possible to estimate the well width with an accuracy of about 10%.
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