Fig. 3
From: Excitons in InGaAs quantum dots without electron wetting layer states
Triply-charged exciton as a probe of the quantum dot (QD) and the wetting layer (WL) states. a X3− counts as a function of the magnetic field for a standard InGaAs QD (measurement and simulation). b As (a) but for an AlAs-capped QD. Note that the line appearing at ~5 T and wavelength ~961 nm arises from X2−, not X3−. c The optical decay process of the X3− singlet. Following photon emission, the p-shell is doubly occupied yet there is a vacancy in the s-shell. This turns on an Auger-like coupling to a state in which a high-lying level is singly occupied (QD-shell or WL-continuum) and the s-shell is doubly occupied. In this way, the PL-process is sensitive to the high-lying state even though it is not occupied in the initial state28. d X3− assuming that angular momentum is a good quantum number: the p-shell has angular momentum Lz = +1 and −1; the d-shell +2, 0 and −2. The X3− ground state changes from a triplet to a singlet at a finite magnetic field. e The final state of the singlet X3−. State \({\mid\! a \rangle}\) can couple to the d-shell of the QD via an Auger-like process (state \({\mid\! b \rangle}\)) and to a Landau level in the WL (state \({\mid\! d \rangle}\)). When d− and p+ come into resonance, state \({\mid\! b \rangle}\) couples to state \({\mid\! c \rangle}\) where one electron occupies the p+-sub-shell
