10 1 $^{.}$10 10 2 $^{.}$10 10 3 $^{.}$10 10 4 $^{.}$10 10 5 $^{.}$10 10 6 $^{.}$10 10 0 0.2 0.4 0.6 0.8 1 1.2 1.192 0.118 T11 nsm 0.5 , 1 , ( ) T11 nsm 0.5 , 2 , ( ) T11 nsm 5 , 1 , ( ) T11 nsm 5 , 2 , ( ) 6 10 ⋅ 1 10 ⋅ nsm 1 2 3 4 5 6 n*10$^{-10 }$(cm$^{-2}$) 1.0  0.8  0.6  0.4  0  T$_{c}$ ( K)  FIG. 1: (Color on line) Kosterlitz-Thouless transition temperature T c as a function of the exciton density n in CQWs fo r different inter-well separations D and phenomenological parameter θ ( n.n e , D ): D = 0 . 5 nm, θ ( n.n e , D ) = 0 . 5 – solid curve; D = 0 . 5 nm, θ ( n.n e , D ) = 0 . 94 – dotted curve; D = 5 nm, θ ( n.n e , D ) = 0 . 5 – dashed curve; D = 5 nm, θ ( n.n e , D ) = 0 . 94 – dashed-dotted curve.