InGaN laser diode with metal-free laser ridge using n⁺-GaN contact layers

Abstract We report on InGaN edge emitting laser diodes with a top metal electrode located beside the laser ridge. Current spreading over the ridge is achieved via a highly doped n + -type GaN layer deposited on top of the structure. The low sheet resistance of the n + -GaN layer ensures excellent lateral current spreading, while carrier injection is confined all along the ridge thanks to current tunneling at the interface between the n + -GaN top layer and the p ++ -GaN layer. Continuous-wave lasing at 400 nm with an output power of 100 mW is demonstrated on uncoated facet devices with a threshold current density of 2.4 kA·cm −2 .