Indium segregation effects in (111)B-grown (In,Ga)As/GaAs piezoelectric quantum wells

The effect of indium surface segregation on electronic states and excitonic properties is investigated experimentally and theoretically in (111)B-grow n (In,Ga)As/GaAs strained piezoelectric quantum wells. Thermally detected o ptical absorption and electroreflectance experiments are performed on two s amples grown by molecular beam; epitaxy and containing 7 and 14 wells, Exci tonic energies and oscillator strengths are calculated by a variational met hod within the effective mass approximation. The influence of indium segreg ation on the piezoelectric field strength and the oscillator strength of ex citonic transitions is analyzed.