Large enhancement of GaN‐UV light emission using silver mirror resonator

Abstract

AbstractIn this paper we used new microcavity resonator design of extracting light with high efficiency from a high index material (GaN), n > 2 for use in light emitting diode (LED) and laser diode (LD). A GaN/sapphire structure as an active layer was sandwiched between two silver mirrors. For the study two types of microcavity were fabricated: (air/GaN/sapphire/silver) and (silver/GaN/sapphire/silver). Via photo‐luminescence measurements we observed 2‐fold intensity enhancement in the UV region (364 nm) at room temperature by using 400 nm silver back mirror compared with uncoated sample. The amplitude of the photoluminescence is enhanced 10‐times when we used 400 nm back coated together with 50 nm silver as front mirror. Further, a tremendous enhancement was obtained when a small hole was made in the front mirror with 50 nm thickness. The large increment of GaN/sapphire light emission in this microcavity could be caused by few important factors: increasing absorption in the cavity, optical field enhancement due to the resonator and coupling of plasmon in the metallic layer with the UV light. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)