OPTIMIZATION OF INGAASP INP QUANTUM-WELL HETEROSTRUCTURES FOR ENHANCED EXCITONIC ELECTROABSORPTION EFFECTS AT 1.55-MU-M/

We report an optimization method on the basis of theoretical calculati on to enhance the excitonic electroabsorption effect in the quaternary InGaAsP/InP quantum well structures for use in the bistable switching devices operating at 1.55 mum wavelength. We searched for the maximum value of a parameter gamma, defined as [alpha(0)-alpha(F)]/alpha (F), by adjusting x, y, and quantum well width in the In1-xGaxAsyP1-y/InP heterostructure assuming that the heavy-hole excitonic absorption peak s at zero electric field occur at 1.55 mum wavelength. We obtained 30. 2 as the maximum value of gamma for y=1.0, x=0.477, and quantum well w idth 90 angstrom, and found that this value is about three times as hi gh as that of the conventional ternary quantum well structure.