Subwavelength plasmonic microcavity light coupling structure for promoting photoelectric detector response

Abstract

The invention discloses a subwavelength plasmonic microcavity light coupling structure for promoting photoelectric detector response rate. The propagation direction and optical field distribution of incident light are modulated through a plasmonic microcavity, thus the incident light is limited to be propagate in the microcavity, the light escape is reduced, and the utilization rate of photons is raised. The incident light is focused in the microcavity such that the intensity is greatly enhanced, and a photoelectric detector with a high response rate can be formed through clamping photoelectric conversion material in the microcavity. The coupling structure is formed by a metal grating layer formed by upper layer periodic metal bars, a photoelectric conversion activation layer and a lower layer metal reflective layer. The subwavelength plasmonic microcavity light coupling structure has the advantages that by using the mode selection effect of an electromagnetic wave near field coupling microcavity formed by plasmonic resonance between the upper layer metal grating and the lower layer metal reflective layer, thus the photons in the microcavity are propagated along a transverse direction to form standing wave, the light field energy is gathered and the length of equivalent optical absorption is increased, and the response rate of the detector is greatly raised.

Description

technical field [0001] The invention relates to a semiconductor photodetector, in particular to a photodetector integrated on a picture element and adopting a sub-wavelength plasmon microcavity coupling structure with improved photodetection capability. Background technique [0002] Semiconductor photodetectors realize the detection of light by absorbing incident photons to form electrons or hole transitions and then changing their conductive state to form photocurrent or photovoltage induced by photogenerated carriers. General photodetectors can directly receive incident light to complete photoelectric detection. However, continuously improving the performance of photodetectors is the goal that people are always pursuing. The figure of merit of a photodetector is the detectivity, and its value directly reflects the performance of the detector. The detectivity is directly proportional to the photoresponsivity, therefore, increasing the photoresponsivity of the photodetecto...

AI Technical Summary

Problems solved by technology

[0004] Ordinary photodetectors that do not use an optical coupling structure are limited by the effective conversion area of ​​photoelectric conversion materials (such as the thickness of the junction region of the p-n junction or the thickness of the photoconductive active layer) and the effective transport length of photogenerated carriers (diffusion length and lifetime ), so that the utilization rate of incident photons is low, and a considerable part of incident photons does not participate in the process of photoelectric conversion but escapes from the detector

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