Spatially resolved STM light emission spectra of cleaved (110) AlGaAs/GaAsheterostructures

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.