Abstract
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.
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