posted on 2020-03-18, 13:50authored byLaxmi
Kishore Sagar, Golam Bappi, Andrew Johnston, Bin Chen, Petar Todorović, Larissa Levina, Makhsud I. Saidaminov, F. Pelayo García de Arquer, Sjoerd Hoogland, Edward H. Sargent
Bright,
narrow spectrum infrared emitters, particularly Cd- and
Pb-free materials, are of interest for bioimaging, photodetection,
and telecommunications. InAs-based quantum dots (QDs) are promising
emitters in this spectral range; however, efforts to increase the
photoluminescence quantum yield (PLQY) tend to broaden the PL line
width as a consequence of interfacial defect formation when thick
shells, lattice-mismatched with the core, are employed. Here we report
that developing a single-precursor complex for InZnP growth enables
uniform shell growth that maintains the excellent size dispersion
(6%) of the cores. The introduction of this intermediate layer is
key to facilitate the subsequent growth of different shells to improve
radiative recombination without sacrificing size uniformity. The growth
of InAs/InZnP/ZnSe leads to a PL full-width at half-maximum (fwhm)
of 100 meV at 1.12 eV with a PLQY of 14%. We then further introduce
an additional GaP layer to increase the radiative/nonradiative relative
rate. InAs/InZnP/GaP/ZnSe QDs reach a PLQY of 23% while maintaining
a narrow fwhm.