The derivative -dN(t)/dlgt of photo-induced excess electrons N(t) in G
aAb-Al-0.3 Ga-0.7 As and In0.15Ga0.85As-Al0.2Ga0.8As heterostructures
with respect to lgt shows a spectrum with pronounced peak-structure. T
he apparent capture energies, the lifetime prefactors, the apparent li
fetime distribution, and the derivative decay quantities of individual
lifetimes were analyzed to distinguish capture mechanisms.