Probing individual localization centers in an InGaN/GaN quantum well.
Photoluminescence (PL) spectroscopy with subwavelength lateral resolution has been employed to probe individual localization centers in a thin InGaN/GaN quantum well. Spectrally narrow emission lines with a linewidth as small as 0.8 meV can be resolved, originating from the recombination of an electron-hole pair occupying a single localized state. Surprisingly, the individual emission lines show a pronounced blueshift when raising the temperature, while virtually no energy shift occurs for increasing excitation density. These findings are in remarkable contrast to the behavior usually found in macro-PL measurements and give a fundamental new insight into the recombination process in semiconductor nanostructures in the presence of localization and strong internal electric fields. We find clear indications for a biexciton state with a negative binding energy of about -5+/-0.7 meV.
Schömig
H
H
Technische Physik, Universität Würzburg, Am Hubland, D-97074 Würzburg, Germany.
Halm
S
S
Forchel
A
A
Bacher
G
G
Off
J
J
Scholz
F
F