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(a) 300 K PL spectra for InAs coverage of 1.97, 2.34, 2.7, 3.06, and 3.33 ML, showing a redshift from 1238 to 1310 nm with increasing the InAs coverage from 1.97 to 2.7 ML and a blueshift as the InAs coverage is increased to 3.06 and 3.33 ML. (b) The corresponding PL spectra at 50 K.
Temperature-dependent PL spectra for the 3.06 ML InAs coverage, showing two predominant families of dots emitting at 1223 and 1300 nm (at 300 K), respectively. While their peak intensities are nearly comparable at 300 K, as temperature decreases to 50 K, the peak intensity at 1223 nm increases in efficiency by a factor of 10 as compared to only 2 for the peak at 1300 nm, suggesting that the dots emitting at 1300 nm are degraded by relaxation.
Temperature dependence of the FWHM of the ground-state peaks for different InAs coverage. In the 3.06 and 3.33 ML samples, the FWHM is obtained from the dominant peaks at 1223 and 1215 nm, respectively.
300-K concentration profiles measured at 1 MHz for different InAs coverage of 1.97, 2.34, 3.06, and 3.33 ML. The relaxed 3.06 and 3.33 ML samples show a relatively weak accumulation peak in the dots and drastic depletion in the bottom GaAs layer.
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