Back-illuminated ultraviolet avalanche photodiode based on delta-doping and preparation method thereof

By using a Δ-doped back-illuminated ultraviolet avalanche photodiode structure, the bottlenecks in material and structural optimization of existing ultraviolet detectors have been overcome, achieving efficient utilization of ultraviolet light and fast response, thus improving the overall performance of the detector.

CN122121287APending Publication Date: 2026-05-29XIDIAN UNIV
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Patent Information

Application Number
CN202610185171.9
Authority / Receiving Office
CN · China
Patent Type
Applications(China)
Current Assignee / Owner
Filing Date
2026-02-09
Publication Date
2026-05-29

AI Technical Summary

Technical Problem

Existing ultraviolet detectors face material, structural, and process bottlenecks when optimizing external quantum efficiency, dark current density, response speed, and detection sensitivity. In particular, high-performance solar-blind ultraviolet detectors face insurmountable challenges in terms of optical loss, dark current noise, and response speed.

Method used

A back-illuminated ultraviolet avalanche photodiode structure based on Δ doping is adopted, including an N-type doped silicon substrate, an intrinsic multiplication region, an epitaxial P-type doped silicon layer, and a P-type boron Δ doped layer. Combined with low-temperature molecular beam epitaxy, a PIN junction structure is formed. The P-type boron Δ doped layer is used to achieve surface passivation and local electric field, thereby optimizing carrier collection and avalanche gain.

Benefits of technology

It significantly improves the effective injection of ultraviolet light, reduces surface dark current, and achieves a comprehensive performance of high external quantum efficiency, low noise, fast response and high gain, meeting the requirements of high-sensitivity detection.

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Abstract

The present application relates to a back-illuminated ultraviolet avalanche photodiode based on delta-doping and a preparation method thereof, comprising: an N-type doped silicon substrate layer; an intrinsic multiplication region I layer, an epitaxial P-type doped silicon layer and a P-type boron delta-doping layer which are sequentially stacked in a direction away from the N-type doped silicon substrate layer and located above the N-type doped silicon substrate layer; wherein the N-type doped silicon substrate layer is located at the back light side of the back-illuminated ultraviolet avalanche photodiode, the P-type boron delta-doping layer is located at the light side of the back-illuminated ultraviolet avalanche photodiode, and the P-type boron delta-doping layer is used to perform a surface passivation function; the intrinsic multiplication region I layer is configured to serve as an avalanche multiplication region under a reverse bias, and the epitaxial P-type doped silicon layer and the N-type doped silicon substrate layer respectively serve as electrodes located on both sides of the avalanche multiplication region to form a PIN junction structure. The device can systematically and cooperatively optimize the ultraviolet detector.
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