Uniqueness of solutions for an elliptic equation modeling MEMS

We study the effect of the parameter $\lambda$, the dimension $N$, the profile $f$ and the geometry of the domain $\Omega \subset\mathbb{R}^N$, on the question of uniqueness of the solutions to the following elliptic boundary value problem with a singular nonlinearity: $$ 180pt {{array}{ll} -\Delta u= \frac{\lambda f(x)}{(1-u)^2} & \hbox{in}\Omega 0