Abstract
Magnetophotoluminescence (MPL) studies as a function of carrier concentration are reported for a series of very high mobility n-type modulation-doped GaAs/(Al,Ga)As single heterojunctions. The measurements were made in high magnetic fields to ∼60 T and at temperatures in the 0.4-2.1 K range. At low fields (v>2), the MPL recombination is dominated a free carrierlike excitonic transition as an energy close to the free exciton in bulk GaAs. The energy and intensity of this excitation undergoes Shubnikov-de Haas-type oscillations at even integer filling factors (v>2) with increasing field. At v=2-, an second strong exciton transition appears at a lower energy primarily in σ- polarization due to a spin ↑ electron recombining with a valence-band hole. It rapidly gains intensity between 2>v>1, but disappears at v= 1+. At v=1- another redshifted transition emerges that has been described as a recombination of an electron in an initial "free hole state." Its intensity in oσ- polarization increases and reaches a maximum between 1>v>1/3. Such behavior becomes more pronounced as the carrier density increases. The redshift at v=1 has been correlated with recent theoretical models describing the theory of photoluminescence of two-dimensional electron systems. It has been used to determine the electron-hole separation as a function of carrier concentration.
Original language | English (US) |
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Article number | 195302 |
Pages (from-to) | 1953021-1953026 |
Number of pages | 6 |
Journal | Physical Review B - Condensed Matter and Materials Physics |
Volume | 64 |
Issue number | 19 |
State | Published - Nov 15 2001 |
Externally published | Yes |
All Science Journal Classification (ASJC) codes
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics