Unbounded Principal Eigenfunctions and the Logistic Equation on R^N

We consider the logistic equation -∆u=a(x)u-b(x)u^p on all of R^N with possibly unbounded coefficients near infinity. We show that under suitable growth conditions of the coefficients, the behaviour of the positive solutions of the logistic equation can be largely determined. We also show that certain linear eigenvalue problems on all of R^N have principal eigenfunctions that become unbounded near infinity at an exponential rate. Using these results, we finally show that the logistic equation has unique positive solution under suitable growth restrictions for its coefficients.