C. Monier et al., Oscillator strength of excitons in (In,Ga)As/GaAs quantum wells in the presence of a large electric field, J APPL PHYS, 85(5), 1999, pp. 2713-2718
The oscillator strength of the fundamental heavy-hole exciton in strained q
uantum well (QW) InxGa1-xAs/GaAs p-i-n diode heterostructures is calculated
by using a variational approach combined with the transfer matrix formalis
m. Unlike the weak well thickness dependence of the excitonic properties in
the absence of electric field, a completely different picture is observed
as the strength of the built-in electric field increases. A dramatic reduct
ion of the QW oscillator strength is noticed for thick wells over the entir
e indium composition range. This is thought to be induced by a very effecti
ve quantum confined Stark effect that becomes a limiting factor for maximiz
ed absorption properties. In contrast, calculations for highly strained (x
> 0.20) thin (less than 50 Angstrom) structures evidence oscillator strengt
h values as large as those found with zero electric field. Finally, the res
ults of this study stress adequate well thickness/composition selection for
improved performance of optoelectronic multiple QW-based devices such as m
odulators and photoconverters. (C) 1999 American Institute of Physics. [S00
21-8979(99)06604-9].