Surface segregation and the Al problem in GaAs quantum wells

Yoon Jang Chung, K. W. Baldwin, K. W. West, M. Shayegan, L. N. Pfeiffer

Research output: Contribution to journalArticlepeer-review

13 Scopus citations


Low-defect two-dimensional electron systems (2DESs) are essential for studies of fragile many-body interactions that only emerge in nearly-ideal systems. As a result, numerous efforts have been made to improve the quality of modulation-doped AlxGa1-xAs/GaAs quantum wells (QWs), with an emphasis on purifying the source material of the QW itself or achieving better vacuum in the deposition chamber. However, this approach overlooks another crucial component that comprises such QWs, the AlxGa1-xAs barrier. Here we show that having a clean Al source and hence a clean barrier is instrumental to obtain a high-quality GaAs 2DES in a QW. We observe that the mobility of the 2DES in GaAs QWs declines as the thickness or Al content of the AlxGa1-xAs barrier beneath the QW is increased, which we attribute to the surface segregation of oxygen atoms that originate from the Al source. This conjecture is supported by the improved mobility in the GaAs QWs as the Al cell is cleaned out by baking.

Original languageEnglish (US)
Article number034006
JournalPhysical Review Materials
Issue number3
StatePublished - Mar 29 2018

All Science Journal Classification (ASJC) codes

  • General Materials Science
  • Physics and Astronomy (miscellaneous)


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