Photoexcitation of excitons in self-assembled quantum dots

Pettersson, H.; Landin, L.; Liu, R.; Seifert, W.; Pistol, M.-E.; Samuelson, L.
November 2004
Applied Physics Letters;11/22/2004, Vol. 85 Issue 21, p5046
Academic Journal
Using an approach of combining Fourier transform infrared spectroscopy with resonant illumination from a secondary external light source, we have measured the photocurrent (PC) for multiple layers of self-assembled InAs dots embedded in a matrix of InP. Without external illumination, we observe photoexcitation of electrons from bound states in the dots to the InP barrier. By additional illumination from the external light source, a strong broadening of the PC signal is observed. We interpret this broadening in terms of photoexcitation of electrons in the presence of additional holes in the dots created by the external light source. We extract the spectral distribution of the photoexcitation process at 6 and 77 K, respectively, and show by comparison with theoretical calculations that it is consistent with an exciton binding energy of 20 meV.


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