Room-temperature operation of c-plane GaN vertical cavity surface emitting laser on conductive nanoporous distributed Bragg reflector

Abstract

Technological feasibility of III-nitride vertical cavity surface emitting laser (VCSEL) has been hindered by the lack of an electrically conductive, easily manufacturable, wide reflection stop band distributed Bragg reflector (DBR). Here, we present the first electrically injected III-nitride VCSEL on an electrically conductive DBR using nanoporous (NP) GaN. The measured threshold current density and the maximum light output power were 42 kA/cm2 and 0.17 mW, respectively, at 434 nm. Vertical injection was demonstrated and showed no deterioration in the threshold current density or slope efficiency, demonstrating the feasibility of vertical injection in NP GaN VCSELs. Filamentary lasing was observed, and its effect on the slope efficiency and the lasing linewidth is studied. Initial measurements showing the correlation between the measured high threshold current density and surface undulations are presented and discussed.