Electrically pumped ultraviolet random lasing action from p-NiO/n-GaN heterojunction

Electrically pumped random lasing has been realized from a p-NiO/n-GaN heterojunction diode. The highly disorderd p-NiO layer, deposited on the commercially available n-GaN substrate by radio frequency magnetron sputtering, supplies multiple optical scattering to sustain coherent optical feedback. The n-GaN layer provides optical amplification to the scattered light propagating inside the heterojunction. Under injection currents larger than 11 mA, a prominent lasing action was discovered with lasing peaks of line width less than 0.6 nm at round 361 nm. The lasing action exhibits the characteristics of random lasing. Furthermore, the mechanism of the light emission was discussed in terms of the band diagrams of the heterojunction in detail.