Interplay between disorder and intersubband collective excitations in the two-dimensional electron gas - art. no. 041306

Intersubband absorption in modulation-doped quantum wells is usually approp riately described as a collective excitation of the confined two-dimensiona l electron gas. At sufficiently low electron density and low temperatures, however, the in-piane disorder potential is able to damp the collective mod es by mixing the intersubband charge-density excitation with single-particl e localized modes. Here we show experimental evidence of this transition. T he results are analyzed within the framework of the density-functional theo ry and highlight the impact of the interplay between disorder and the colle ctive response of the two-dimensional electron gas in semiconductor heteros tructures.