Cracking self-assembled InAs quantum dots

D.M. Bruls, J.W.A.M. Vugs, P.M. Koenraad, M.S. Skolnick, M. Hopkinson, J.H. Wolter

Research output: Contribution to journalArticleAcademicpeer-review

12 Citations (Scopus)


We present a cross-sectional scanning tunneling microscopy (X-STM) investigation of InAs quantum dots in a GaAsmatrix. The structures were grown by molecular beam epitaxy (MBE) at a low growth rate of 0.01ML/s and consist of five layers of uncoupled quantum dot structures. Detailed STM images with atomic resolution show that the dots consist of an InGaAs alloy and that the indium content in the dot increases towards the top. The analysis of the height versus base-length relation obtained from cross-sectional images of the dots shows that the shape of the dots resembles that of a truncated pyramid and that the square base is oriented along the [010] and [100] directions. Using scanning tunneling spectroscopy (STS) we determined the onset for electron tunneling into the conduction and out of the valence band, both in the quantum dots and in the surroundingGaAs matrix. We found equal voltages for tunneling out of the valence band in GaAs or InGaAs whereas tunneling into GaAs occurred at higher voltages than in InGaAs.
Original languageEnglish
Pages (from-to)S205-S207
JournalApplied Physics A: Materials Science & Processing
Issue numberSuppl.2
Publication statusPublished - 2001


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