Negatively charged excitons and photoluminescence in asymmetric quantum wells
We study photoluminescence (PL) of charged excitons (X{sup -}) in narrow asymmetric quantum wells in high magnetic fields B. The binding of all X{sup -} states strongly depends on the separation {delta} of electron and hole layers. The most sensitive is the ''bright'' singlet, whose binding energy decreases quickly with increasing {delta} even at relatively small B. As a result, the value of B at which the singlet-triplet crossing occurs in the X{sup -} spectrum also depends on {delta}, and decreases from 35 T in a symmetric 10 nm GaAs well to 16 T for {delta}=0.5 nm. Since the critical values of {delta} at which different X{sup -} states unbind are surprisingly small compared to the well width, the observation of strongly bound X{sup -} states in an experimental PL spectrum implies virtually no layer displacement in the sample. This casts doubt on the interpretation of PL spectra of heterojunctions in terms of X{sup -} recombination.
- Sponsoring Organization:
- (US)
- OSTI ID:
- 40205568
- Journal Information:
- Physical Review B, Vol. 63, Issue 8; Other Information: DOI: 10.1103/PhysRevB.63.085305; Othernumber: PRBMDO000063000008085305000001; 030108PRB; PBD: 15 Feb 2001; ISSN 0163-1829
- Publisher:
- The American Physical Society
- Country of Publication:
- United States
- Language:
- English
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