EN
An inclusion of cubic GaN in an otherwise hexagonal matrix is considered to be equivalent to an effective quantum well. The exciton binding energy in a quantum well of a finite potential barrier height in the conduction and valence bands is calculated in the effective mass approximation with a variational envelope function type of Bastard and Takagahara. The exciton binding energy and the energy of exciton recombination line are computed, as a function of the well width, for realistic potential barrier heights and band-offset ratios.