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(a) Streaky RHEED pattern showing flat GaP buffer surface before SAQD deposition. (b) Spotty RHEED pattern after coverage. (c) Streaky pattern recovered after GaP cap growth. (d) Bright field, , XVTEM image of 5.0 ML SAQDs capped with GaP. Under these imaging conditions, both the SAQDs and wetting layer (see inset) are visible. Neither dots nor GaP cap showed any evidence of dislocations under numerous two-beam conditions.
PL spectra of the 5.0 ML SAQD sample (upper) and the GaP buffer (lower) under 3.07 eV (404 nm) laser pumping at 80 K. Inset photograph: red PL emission at 1.94 eV from the SAQD sample is readily visible to the unaided eye.
(a) PL spectra at 80 K from buried SAQDs for various deposition thicknesses. (b) and FWHM as a function of coverage. moves to lower energy with greater deposition thickness. The extracted FWHM for all peaks is in the range of 115–125 meV. Nonuniformity in SAQD size is likely to be the major contributing factor to FWHM.
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