Hyperspherical coordinates are applied to the bound states of two-dimension
al charged excitons. The Schrodinger equation is solved by two different me
thods, i.e., by a direct expansion in hyperspherical harmonics and by separ
ating it into a radial equation and an angular equation on the basis of the
adiabatic approximation. Our main findings are: (a) the low-lying eigenene
rgies scale nearly linearly with the reduced mass of the exciton; (b) the a
diabatic approximation produces a ground-state energy of -1.1384 au, which
compares well to -1.1164 au, obtained by hyper spherical expansion in the p
ositronium limit.