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(a) Energy and optical transition diagram of the InGaN QW with and without an applied magnetic field , when and . The -polarized optical transitions between the conduction band (CB) and valence band (VB) are indicated by arrows. Energy levels and optical transitions related to the C VB state are not included here. Here , and denote the projections of the CB electron spin angular momentum, VB electron orbital and spin angular momentum onto their quantization axis , respectively. (b) Energy diagram of the exciton and related spin relaxation processes. The notation is used here for the excitonic states, where , and denote the projections of CB electron spin, VB hole orbital and spin angular momentum, respectively; , and .
Time-integrated PL spectra of the InGaN QW from Spin LED and Ref LED, measured at 2 K and 0 T.
Experimental decay curves of the (thin solid lines) and (thin dotted lines) PL components of the InGaN QW from (a) Spin LED and (c) Ref LED, measured at 2 K at 0 and 4 T. Thick solid and dashed lines are fitting curves of the and PL components, respectively. Except for the PL component at 4 T that is fitted by two exponents (50 ps and 2 ns), a single exponent of 2 ns is used in the fitting; (b) and (d) show PL polarizations from Spin LED and Ref LED, respectively, as a function of delay time at (thin dotted lines) and (thin solid lines). The thick solid and dashed lines are fitting curves at 0 and 4 T, respectively, with identical fitting parameters as that in (a) and (c). The main PL peak within the energy range of 2.638–2.818 eV was monitored here.
Simulated PL decay curves when (a) exciton spin relaxation dominates ; (b) individual carrier spin relaxation dominates , obtained by an analysis of coupled differential rate equations. The following values are used: (at 0 T), and (at 4 T).
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