Effect of hydrogen on modulation-doped AlGaAs/InGaAs/GaAs heterostructures: a photoluminescence study

The effect of hydrogen on donors and interface defects in silicon modulation doped AlxGa1-xAs/InyGa1-yAs/GaAs heterostructures has been investigated by photoluminescence (PL). Hydrogenation was carried out on two sets of samples, one set consists of high quality pseudomorphic heterostructures and another set having partially lattice relaxed structures prone to the defects. On exposure of high quality pseudomorphic structures to hydrogen plasma above 150degreesC, a significant blue shift in the PL peak positions as well as bandwidth narrowing is observed. This indicates, the reduction in two-dimensional electron gas in the InyGa1-yAs quantum well due to hydrogen passivation of silicon donors in the AlxGa1-xAs supply layer. The reactivation of the donors is observed upon annealing the hydrogenated sample for 1 h at 250degreesC under hydrogen ambient. Another interesting feature is a significant improvement in the PL of lattice-relaxed structures upon hydrogenation of the samples above 250degreesC, which is attributed to the hydrogen passivation of interface defects due to the misfit dislocations. (C) 2004 Elsevier Ltd. All rights reserved.