Photoelectric detector and preparation method thereof

Abstract

The invention relates to a photoelectric detector and a preparation method thereof. The photoelectric detector is of a transverse PN junction structure or a longitudinal PN junction structure, and comprises a semiconductor substrate provided with top-layer silicon, wherein a cone-shaped silicon waveguide is formed on the top silicon, the cone-shaped silicon waveguide is provided with a first end and a second end, and the area of the first end is smaller than that of the second end; the upper surface, close to the first end, of the silicon waveguide is covered with a first polycrystalline silicon layer; the upper surface, close to the second end, of the silicon waveguide is covered with a germanium layer, and the germanium layer and the first polycrystalline silicon layer are spliced together; wherein the P doped region and the N doped region are arranged in the top silicon layer and/or the germanium layer; and electrodes respectively formed on the upper surfaces of the P-doped region and the N-doped region. The coupling structure of the germanium-silicon photoelectric detector input waveguide active absorption region is optimized, high-efficiency coupling of the germanium-silicon photoelectric detector input waveguide active absorption region and the germanium-silicon photoelectric detector can be achieved, response is improved, and device power consumption is reduced.

Description

technical field [0001] The invention relates to the field of semiconductors, in particular to a photodetector and a preparation method thereof. Background technique [0002] Photodetectors are an important part of photonic integrated chips. Compared with the surface incidence detector, the waveguide detector can greatly increase the absorption length under the premise of maintaining the thickness of the absorbing layer. The propagation and absorption of light are along the direction of the waveguide, while the carrier transport is along the perpendicular direction. The direction can significantly improve the response speed and obtain high internal quantum efficiency; at the same time, the device area is smaller and the dark current is relatively low, which can significantly improve the noise and improve the sensitivity of the device. Therefore, photodetectors with this structure have attracted extensive attention. [0003] Efficient optical coupling and transmission is the...

AI Technical Summary

Problems solved by technology

[0003] Efficient optical coupling and transmission is the key to the reliable application of optoelectronic devices, but in waveguide detectors, due to the mode mismatch between the waveguide and the germanium layer absorption region, there is a large coupling loss in direct coupling

At the same time, due to the interface defects between the silicon layer and the germanium layer, if the absorption region of the germanium layer is too long, the dark current of the detector will increase significantly.

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