Superlinear increase of photocurrent due to stimulated scattering into a polariton condensate

We show that when a monopolar current is passed through an $n\text{\ensuremath{-}}i\text{\ensuremath{-}}n$ structure, superlinear photocurrent response occurs when there is a polariton condensate. This is in sharp contrast to the previously observed behavior for a standard semiconductor laser. Theoretical modeling shows that this is due to a stimulated exciton-exciton scattering process in which one exciton relaxes into the condensate, while another one dissociates into an electron-hole pair.