We have measured the spectra of light emitted from individual single GaAs q
uantum wells of cleaved (1 1 0) AlGaAs/GaAs heterostructures using the STM
(scanning tunneling microscope) tip as a local electron injection source. T
he cross-sectional STM images of the quantum wells were obtained, and the l
ight emission spectra were measured by locating the STM tip over individual
quantum wells of interest. Single emission peaks were observed to shift to
the high-energy side with decreasing well width. The peak positions agree
with the calculated transition energies for the corresponding well width. T
he thermalization length of the injected electron was estimated by observin
g the change in the emission intensity as the tip is moved at different dis
tances from a given well. (C) 2001 Elsevier Science B.V. All rights reserve
d.