Coupled plasmonic-passivation luminescence enhancement in InGaN quantum wells with Ag/AlN capping

Ag/AlN is investigated as an advantageous metal/dielectric combination for enhancing the radiative efficiency of InGaN multi-quantum well (MQW) structures via both passivation and plasmonic mechanisms. Steady-state and time-resolved photoluminescence (PL) measurements facilitate separation of these coupled effects, demonstrating almost complete elimination of parasitic recombination channels via AlN-related surface passivation alone. In agreement with theory, an additional Ag layer yields PL enhancements of 7.0-8.3× in the top QW closest to the plasmonic metal interface, with progressive reduction in deeper QWs. The high passivation efficiency of even thin AlN enables close proximity of the plasmonic layer and MQW active region, with increased spontaneous emission rates as high as 8.1× resulting from strengthened resonant coupling to Ag surface plasmons.