We have independently estimated the conduction- and valence-band offsets ΔEc and ΔEv in GaAs/Ga0.51In0.49P quantum wells by measuring the capacitance transient resulting from thermal emission of carriers from the respective wells. The heterostructure samples were grown by low-pressure metalorganic chemical vapor deposition. The band offsets are extrapolated from the emission activation energies with appropriate corrections. The estimated values of ΔEc and ΔEv are 0.198 and 0.285 eV, respectively.

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Experimental and theoretical studies are presented for exciton transitions in p-i-n GaAs/AlGaAs multiple coupled-quantum-well structures where each quantum well consists of two identical wells with a thin barrier. Electroabsorption and photocurrent studies are carried out to identify how the excitonic peaks respond to transverse electric fields. With a careful choice of the dimensions of the coupled quantum well, it is seen that the lowest heavy-hole exciton peak moves at a rate ∼2.5 faster than in a square well. Thus strong modulation is obtained at much lower electric fields. The nature of the higher-energy transitions is also studied.

An Arrhenius-type of expression is derived for the emission rate of electrons from a quantum well on the basis of detailed balance principles. The formulation is applied to a 150-Å In0.2Ga0.8As/Al0.16Ga0.84As strained single quantum well grown by molecular beam epitaxy. From an analysis of the data it is possible to estimate the conduction band offset ΔEc, which may be extremely useful for strained systems.