Schüller, Christian and Broocks, K.-B. and Heyn, Ch. and Heitmann, Detlef (2002) Oscillator strengths of dark charged excitons at low electron filling factors. Physical Review B (PRB) 65; 4 , 081301.
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By direct absorption spectroscopy and comparison to photoluminescence (PL), we investigate negatively charged excitons in dilute two-dimensional electron systems at temperatures down to T = 40 mK in the regime of the fractional quantum Hall effect. At very low temperatures, for filling factor nu<1/3, an additional excitation appears in the PL spectrum, between the well-known singlet and triplet excitons. The observation of a similar excitation by PL was reported very recently [G. Yusa et al., Phys. Rev. Lett. 87, 216402 (2001)], and the excitation was assigned, in spite of the PL intensity similar to that of the neutral exciton, to be due to a dark triplet exciton. By comparing PL and direct absorption spectra in optically thin samples at T<100 mK, we can identify the new excitation indeed as a "dark" mode, since we find that the oscillator strength is much smaller than those of the "bright" modes.
|Date:||29 July 2002|
|Institutions:||Physics > Institute of Experimental and Applied Physics > Chair Professor Lupton > Group Christian Schüller|
|Keywords:||aluminium compounds, gallium arsenide, semiconductor quantum wells, III-V semiconductors, oscillator strengths, excitons, photoluminescence, light absorption, two-dimensional electron gas, quantum Hall effect, triplet state|
|Subjects:||500 Science > 530 Physics|
|Created at the University of Regensburg:||Unknown|
|Deposited On:||21 Sep 2009 07:17|
|Last Modified:||20 Jul 2011 21:44|