III-Nitride Electrically Pumped Visible and Near-Infrared Nanowire Lasers on (001) Silicon

Abstract Ga(Al,In)N nanowires can be grown catalyst-free on silicon and other substrates. The diameter of individual nanowires in an array and the array density can be varied over wide ranges. Single or multiple InGaN disks can be inserted in Ga(Al)N nanowires and the alloy composition in the disk can be varied to tune the luminescence from visible to near infrared. The nanowires have other desirable properties such as very low density of extended defects and minimal strain. They can also be selectively doped n- and p-type, thereby enabling the formation of junction diodes as with planar materials. With adequate passivation the internal quantum efficiency of GaN nanowires and the InGaN disks, which behave as quantum dots, is higher than 50%. We have exploited these favorable attributes to design, epitaxially grow and characterize the first edge-emitting electrically pumped GaN/In(Ga)N disk-in-nanowire lasers with the peak of the coherent emission varying from 533 nm (green) to 1.3 μm. It may be noted that light sources with emission at wavelengths larger than 590 nm cannot be realized with InGaN/GaN quantum wells (QWs). The characteristics of the nanowire heterostructures and the steady-state and small-signal modulation characteristics of the lasers are described. The threshold current, characteristic temperature T 0 , differential gain, and modulation bandwidth of the nanowire lasers are comparable to state-of-the-art QW and quantum dot lasers.