A high-speed photodetector structure and its manufacturing method

Abstract

The invention discloses a high-speed photodetector structure. The epitaxial wafer includes an InP substrate, and a lower ohmic contact layer, a lower window layer, an absorption layer, an upper window layer, and an upper ohmic contact layer grown sequentially on the InP substrate from bottom to top. A contact layer, the epitaxial wafer is arranged as a mesa structure, one side of the mesa structure is a light incident surface, the incident surface is provided with an anti-reflection film, and the other side away from the anti-reflection film is a light reflection surface, A high reflection film is provided on the light reflection surface. The light incidence direction of the photodetector of the present invention is perpendicular to the direction of the drift electric field, the absorption layer is 0.1-3um, the carrier drift is fast, and the bandwidth is high; the present invention further reduces the device size and improves the device bandwidth while improving the internal quantum efficiency. , to balance the uniform distribution of the photocurrent in the entire absorbing layer, and avoid the signal nonlinear distortion problem caused by the uneven light absorption of the absorbing layer and local photocurrent saturation.

Description

technical field [0001] The invention relates to the technical field of photodetectors, in particular to a high-speed photodetector and a manufacturing method thereof. Background technique [0002] Optical detectors are widely used in optical communication systems, imaging systems and military fields, and are key optical receiving devices in high-speed optical communication systems. Photodetectors are developing towards high performance and high integration. Optical detectors used in optical fiber communication systems can generally be classified into two types: photodiodes (PDs) and avalanche photodiodes (APDs). The frequency response bandwidth and quantum efficiency of traditional photodetectors restrict each other. Generally, the quantum efficiency of the device can be increased by increasing the absorbing layer of the device, but the transit time of the carriers becomes longer and the response rate decreases. In photodetectors, the absorption of photons occurs in the a...

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Problems solved by technology

However, the resonator-enhanced (RCE) photodetector has the characteristics of high-speed response due to the thin thickness of the absorbing layer. However, due to the small difference in refractive index between the two materials in the epitaxially grown DBR, it is necessary to achieve a higher reflectivity. , the logarithm of DBR is more, and the thickness of DBR is very thick by epitaxial growth, which increases the difficulty and cost of the process, and also leads to a large parasitic resistance of the device, which affects the bandwidth of the device.

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