Surface-plasmon-enhanced light emitters based on InGaN quantum wells

Since 1993, InGaN light-emitting diodes (LEDs) have been improved and commercialized, but these devices have not fulfilled their original promise as solid-state replacements for light bulbs as their light-emission efficiencies have been limited. Here we describe a method to enhance this efficiency through the energy transfer between quantum wells (QWs) and surface plasmons (SPs). SPs can increase the density of states and the spontaneous emission rate in the semiconductor, and lead to the enhancement of light emission by SP-QW coupling. Large enhancements of the internal quantum efficiencies (ηint) were measured when silver or aluminium layers were deposited 10 nm above an InGaN light-emitting layer, whereas no such enhancements were obtained from gold-coated samples. Our results indicate that the use of SPs would lead to a new class of very bright LEDs, and highly efficient solid-state light sources.