TIGHT-BINDING APPROACH TO EXCITONS BOUND TO MONOLAYER IMPURITY PLANES- STRONG RADIATIVE PROPERTIES OF INAS IN GAAS

A theory of Wannier-Mott excitons bound to monolayer (ML) impurity pla nes in semiconductors, which is based on Green's function tight-bindin g calculations of the single-particle states, is presented. Binding en ergies and oscillator strengths for one and two MLs of InAs in GaAs ar e predicted to be much larger than in the usual InxGa1-xAs/GaAs thick quantum wells. The reason is the increase of effective mass of both ca rriers due to folding of the InAs bands along the growth direction. Th e results suggest that ML insertions can be used as intense light sour ces in light-emitting devices.