Electrically pumped ultraviolet random lasing from ZnO films: Compensation between optical gain and light scattering

Abstract

We have demonstrated the compensation between optical gain and light scattering in electrically pumped random lasing (RL) from ZnO films through investigating the electroluminescence of MgxZn1−xO/ZnO (x=0.25 and 1) heterostructured devices. As the active ZnO films are sol-gel derived, both heterostructured devices can be electrically pumped into RL at appropriate forward currents. While the active ZnO films are prepared by sputtering, only the MgO/ZnO heterostructured devices can generate RL pumped with sufficient forward currents. It is believed that the light scattering in the sputtered ZnO films is weaker than that in the sol-gel derived ones. However, the inferior light scattering capability of the sputtered ZnO films can be compensated by the MgO/ZnO-heterostructure-enabled higher optical gain in the electrically pumped RL.