Abstract
We investigate the properties of a X– trion formed in a polarized nitride heterostructure from an excitoninteracting with a two dimensional electron gas (2DEG). We evidence here dramatic changes induced inthe excitonic features by moderate to large densities of carriers in such quantum structures. Band fillingeffects and dielectric constant screening are accounted for in our model which also provides us with theability to determine the spin-flip exchange energy separating the singlet from the triplet states of such atrion as a function of the 2DEG density.