Electro- and photoluminescence in graded bandgap nanostructures at moderate double injection level

The intensities of electro- (EL) and photoluminescence (PL) in graded-bandgap semiconductor structures operating in the double injection mode are calculated. The cases of the band-to-band radiative recombination and radiative recombination via centers are considered. The dependencies of the intensity of luminescence on current and incident radiation intensity for different lengths of the base and energy bands gradients are analyzed. It is shown that linear, quadratic or cubic dependencies for the EL intensity on current with smooth transitions between them are possible for the band-to-band radiative recombination case. In the dependence of the PL intensity on incident radiation intensity, besides the linear term, there is a quadratic one getting sharper with an increase in the current.