Strong graded interface related piezoelectric polarization weakening effects on exciton confinement in single InxGa1-xN/GaN quantum wells

We consider how the weakening of piezoelectric polarization effects due to the existence of graded interfaces modifies the confined exciton properties in In0.2Ga0.8N/GaN single quantum wells. The balance between the red shift of the exciton energy related to the enormous polarization electric field inside the well, and its strong blue shift resulting front the existence of graded interfaces as thin as three monolayers, is shown to be important. We conclude that a better interface characterization is more fundamental to better estimates of the confined exciton energy in InxGa1-xN/GaN quantum wells than an improved knowledge of the carriers effective masses and the band offset in actual samples. (C) 2002 Elsevier Science B.V. All rights reserved.