OPTICAL INVESTIGATION OF PIEZOELECTRIC FIELD EFFECTS ON EXCITONIC PROPERTIES IN (111)B-GROWN (IN,GA)AS GAAS QUANTUM-WELLS/

The excitonic properties in two (111)B-grown In0.15Ga0.85As/GaAs multi ple quantum well p-i-n diodes are investigated by thermally-detected o ptical absorption and electroreflectance measurements. The lineshape o f the electroreflectance spectra is analysed by means of a multilayer model enabling the energies and the oscillator strengths of excitonic transitions to be deduced. The excitonic characteristic values are cal culated by using a variational method. The determination of the variat ion of the binding energy with in-well field leads to an accurate Valu e of the piezoelectric field in the InGaAs layers. The theoretical osc illator strengths are compared to those obtained from electroreflectan ce for different excitonic transitions. (C) 1997 Elsevier Science Ltd.