Energy diagram and recombination mechanisms in InGaN/AlGaN/GaN heterostructures with quantum wells

Electroluminescence spectra of GaN based LEDs are analyzed quantitatively u sing a model of 2D density of states with band tails. Calculations take int o account an energy diagram with given band offsets between AlGaN, InGaN an d GaN layers. The model describes spectral shapes with four fitting paramet ers in a wide range of currents and intensities with a good accuracy. Fluct uations of well thickness (heterointerface roughness), of In content, of ch arged impurities and piezoelectric fields are discussed for an evaluation o f the exponential tail parameter of 2D density of states in the active regi on. Spectral maxima move with current changes due to the filling of the ban d tails and redistribution of current carriers between regions with a large r probability of radiative recombination. 2D concentrations and lifetimes o f minority carriers in active layers are evaluated from the parameters of t he model.