INTERSUBBAND TRANSITIONS FOR DIFFERENTLY SHAPED QUANTUM-WELLS UNDER AN APPLIED ELECTRIC-FIELD

Calculations were made to compare the Stark shifts of electron intersubband transitions in Al0.4Ga0.6As/AlxGa1-xAs quantum wells. Several differently shaped quantum wells, having the same subband spacing between the ground and first excited states, E21 = 124 meV (= 10-mu-m) under zero bias, were considered. The asymmetric steplike wells showed larger intersubband Stark shifts and a relatively high oscillator strength as well as a small linewidth broadening. A linear intersubband Stark shift of +/- 10 meV for +/- 100 kV/cm with a moderate change of the oscillator strength was found for an asymmetric well with its potential shape intermediate between a square and an asymmetric triangular one.