We show for the first time that strongly directional emission of defined polarization can be achieved from conventional AlGaAs/GaAs double-heterostructure surface-emitting light-emitting diodes (LEDs) via coupling to surface plasmons. By microstructuring the surface, we have fabricated LEDs with a beam divergence of less than 4° and an increased quantum efficiency. It is demonstrated that the surface plasmon excitation and emission mechanism have the potential to improve the performance of LEDs.

A polarization detector based on the excitation of surface plasmon polaritons on the periodically corrugated metal surface of Schottky structures is presented. The surface modes are only excited by light having the appropriate polarization; they are leaky at the metal-semiconductor interface and are thus radiated into the semiconductor, where they generate charge carriers. By this mechanism the photocurrent of the device is enhanced and depends strongly on the polarization angle of the incident light. By use of two detectors with different grating orientations the polarization of the light can be determined unambiguously.

In this letter, the influence of metal films and dielectric waveguides on the radiation characteristics of light emitting diodes (LEDs) is investigated. Cross and hexagonal surface grating structures are used to excite surface plasmons and waveguide modes in these media. A beam divergence as small as 17° is achieved for a hexagonal grating coated with a 40 nm Ag film. The maximum quantum efficiency is found for a hexagonal grating with a 10-nm-thick Au film and a 250-nm-thick dielectric layer. The optical power emitted by this LED into the solid angle from −30° to 30° is 10% higher than that of an LED without metal film and dielectric layer.

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We have investigated the light emission from forward- and reverse-biased sinusoidally structured Ag/n-GaAs Schottky diodes. Sinusoidally structured Schottky junctions show increased light emission because of the radiative decay of excited surface plasmon polaritons, resulting in drastically enhanced quantum efficiency. A model explaining excitation and emission of surface plasmon polaritons is presented.