Example: Blue MQW LED heterostructure
Figure 1 Schematic view of the heterostructure, see
S.S. Mamakin et al., Semiconductors 37 (2003) 1107
Figure 2 (a) Band diagram
Figure 2 (b) Carrier concentrations
Figure 2 (c) Recombination rates
Band diagrams, and distributions of carrier concentrations and
recombination rates in the LED structure. It is seen that electrons
are uniformly distributed over different QWs. In contrast, holes are
injected mainly into the QW adjacent to the p-AlGaN emitter.
Computations predict that the hole distribution over the QWs becomes
much more uniform if the lightly doped barriers are employed in the
LED structure. This is due to a lower carrier recombination rate (a
higher diffusion length) in the active region directly controlled by
the electron concentration.
You can find detailed discussion of MQW heterostructure for blue LED in
the article by V.F. Mymrin, K.A. Bulashevich, N.I. Podolskaya, I.A.
Zhmakin, S.Yu. Karpov, and Yu.N. Makarov “Modelling study of MQW LED
operation”, phys. stat. sol. (c) 2, 2928-2931 (2005)
Figure 3 Dependence of Internal Emission Efficiency predicted numerically
and External Efficiency measured experimentally on current density