Evolution of a dominant light emission mechanism induced by changes of the quantum well width in InGaN/GaN LEDs and LDs

We examined electroluminescence from In 0.17 Ga 0.83 N/GaN quantum wells (QW) of light-emitting diodes (LEDs) and laser diodes (LDs). For increasing QW width we observe transition from electron and hole ground-states recombination to excited states recombination. The effect is accompanied by partial (2.6 nm, 5.2 nm, 7.8 nm QW) or practically complete (10.4 nm QW) screening of the built-in electric field with increasing driving current for both types of emitters. The electric field magnitude was studied using an original high pressure method. The investigations are supported by simulations of the variation with driving current of i) electron and hole wavefunctions overlap affecting the recombination channel, ii) built-in electric field.