InAs avalanche photodiode and method for manufacturing same

Abstract

The invention relates to an avalanche photodiode and a method for manufacturing the same, in particular to an InAs avalanche photodiode. The photodiode is of an absorbed charge multiplication and separation structure, and multiplication layers are of super-lattice structures. The invention further relates to a method for manufacturing the InAs avalanche photodiode. The method mainly includes steps of S1, generating the multiplication layers of the super-lattice structures with multiple quantum wells; S2, generating charge layers, gradient layers and optical window layers; and S3, forming PN junctions by an Zn diffusion process or a Cd diffusion process. The InAs avalanche photodiode and the method have the advantages that dark current, particularly tunneling dark current, is mainly reduced by the super-lattice structures of the multiplication layers for the narrow-gap attribute of InAs materials; and wide-gap materials matched with the InAs materials are adopted, various structures of the photodiode are further optimized, and accordingly effects of low noise, high gain, high speed and high response are realized.

Description

technical field [0001] The invention belongs to the technical field of photodiodes, in particular to an InAs avalanche photodiode and a manufacturing method thereof. Background technique [0002] At present, due to the rapid development of optical communication systems, the requirements for the responsivity and speed of the receiver are getting higher and higher. Compared with PIN detectors, avalanche photodiodes (APDs) have higher sensitivity due to their internally generated gain, and are widely used in optical communication systems. However, due to the randomness of the gain, it will be accompanied by additional noise; and for traditional APDs such as InAlAs, InP, Si, InGaAs and other APDs, there is a limit to the gain-bandwidth product, that is, when the gain is high, due to the increase in the avalanche settling time , the bandwidth will be reduced, thus limiting the rate of the receiver. Therefore, APDs with low noise, high response, low dark current, and high gain b...

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Problems solved by technology

At present, there are some mainstream methods to reduce the dark current of InAs, such as: 1) low-temperature working method, which enables the APD to work in the range of 290K-77K in a refrigerated environment. Compared with 290K, the dark current at 77K can be reduced by 6 orders of magnitude, but The gain is also reduced from 17 to 8, which reduces the maximum gain-bandwidth product, limits the available gain, and works under cooling, requiring an additional cooling device, which is inconvenient to apply to communication systems; 2) Improve the manufacturing process and add a diffusion barrier layer method, which reduces the surface dark current and bulk diffusion current respectively. When the growth temperature of InAs is 470°C, the lattice defects are small. The method of two-step etching is adopted. First, the ratio of 1:1:1 is used. h 3 PO 4 :H 2 o 2 :H 2 O solution followed by 1:8:80 H 2 SO 4 :H 2 o 2 :H 2 O solution, which can reduce the dark current by an order of magnitude, using AlAs 0.16 Sb 0.84 The wide bandgap acts as a minority carrier blocking layer to prevent minority carriers in the p-type contact layer from diffusing to the intrinsic multiplication region, and can also reduce the dark current by an order of magnitude, but the dark current is still high; 3) He ion-implanted planar structure, using ion The method

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