Effect of two-layer (In 0.04 Ga 0.96 N and In 0.08 Ga 0.92 N) staircase electron injector (SEI) on quantum efficiency of light-emitting-diodes (LEDs) in the context of active regions composed of single and quad 3 nm double heterostructures (DHs) is reported. The experiments were augmented with the first order model calculations of electron overflow percentile. Increasing the two-layer SEI thickness from 4 þ 4 nm up to 20 þ 20 nm substantially reduced, if not totally eliminated, the electron overflow in single DH LEDs at low injections without degrading the material quality evidenced by the high optical efficiency observed at 15 K and room temperature. The improvement in quad 3 nm DH LEDs with increasing SEI thickness is not so pronounced as the influence of SEI is less for thicker active regions, which in and of themselves necessarily thermalize the carriers. V