Abstract
We study the photoluminescence (PL) spectra of nominally undoped GaAs/As quantum wells, as a function of well width, temperature, excitation energy, and intensity, and an applied magnetic field. A doublet is observed for temperatures below 10 K, whose components we demonstrate derive from the neutral (X) and positively charged () excitons. The latter appears due to the binding of excitons to holes in the quantum well originating from the background concentration of acceptors in the As barriers. Our assignment of is motivated by the striking similarity of the PL spectra to those recorded on quantum wells with acceptors deliberately incorporated in the barriers. Consistent with our assignment, we see a strengthening of the transition when more holes are introduced into the well by photoexcitation. The dependence of the doublet splitting on well width is in close agreement with a Monte Carlo calculation of the second hole binding energy in . The PL peak due to may have been falsely ascribed in previous work to a biexciton. © 1996 The American Physical Society.
- Received 17 January 1996
DOI:https://doi.org/10.1103/PhysRevB.53.13002
©1996 American Physical Society