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Avalanche Photo Diode

a photo diode and avalanche technology, applied in the field of light receiving elements, can solve the problems of easy breakage on the surface of the mesa periphery, and achieve the effects of low dark current, high long-term reliability, and simple process

Inactive Publication Date: 2008-08-14
MITSUBISHI ELECTRIC CORP
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

[0012]According to the invention, there can be provided an avalanche photodiode with low dark current and high long-term reliability in a simple process.

Problems solved by technology

However, a breakdown easily occurs on the surface of the mesa periphery.
The planar structure is a structure in which a pn junction is formed by providing a selective diffusion region, but an edge breakdown in the edge part of the pn junction introduces a problem.

Method used

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Experimental program
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first embodiment

[0025]FIG. 1 is a sectional view to show the schematic structure of an avalanche photodiode according to a first embodiment of the invention. Here, n type is used as a first conduction type, p type is used as a second conduction type, an n electrode is used as a first electrode, and a p electrode is used as a second electrode. Each semiconductor layer can be manufactured using MO-CVD, a molecular beam epitaxy (MBE), etc., on a wafer-like substrate 1 of n type InP, etc., for example. In the embodiment, the semiconductor layers are manufactured according to the following step order; A first semiconductor layer 2 (which will be hereinafter referred to as buffer layer) of n type InP, etc., at a carrier density of 0.2 to 2×1019 cm−3 is grown to a thickness of 0.1 to 1 μm, an avalanche multiplication layer 4 of i type AlInAs is grown to a thickness of 0.15 to 0.4 μm, a field relaxation layer 5 of p type InP at a carrier density of 0.5 to 1×1018 cm−3 is grown to a thickness of 0.03 to 0.06...

second embodiment

[0033]FIG. 4 is a sectional view to show a schematic structure of an avalanche photodiode according to a second embodiment of the invention. In the present embodiment, in the avalanche photodiode according to the first Embodiment, a third semiconductor layer 15 with a larger band than the light absorption layer 6 and formed of i type InP having about 0.03 μm is provided between the light absorption layer 6 and the second semiconductor layer 8, and a groove 10 is formed by leaving the third semiconductor layer 15.

[0034]According to the present embodiment, the lower portion of the groove 10 exposed to the outside can be formed with a larger band gap than the light absorption layer 6. Therefore, it is possible to achieve suppression of surface deterioration in the lower portion of the groove 10, suppression of deterioration in dark current characteristics, and improvement in durability. In addition, the region in which electric field strength thereof is partially high in the periphery ...

third embodiment

[0038]FIG. 5 is a sectional view to show a schematic structure of an avalanche photodiode according to a third embodiment of the invention. In the present embodiment, in the avalanche photodiode according to the first embodiment, an outer trench 26 is further provided in the outer periphery of the inner region 110 separated by the groove 10 and by removing up to the light absorption layer 6, for example, so that a circular region is left about 100 μm in diameter to form the side face 25.

[0039]In the present embodiment, since the avalanche photodiode has the groove 10 formed therein, a depletion region 11 is formed right under the inner region 110. The dark current occurs mainly from the light absorption layer 6 and flows through the depletion region 11 and along the side face of the element. Accordingly, when the outer trench 26 is provided in the periphery of the light absorption layer 6 surrounding the depletion region 11, it is possible to shut off the path of the dark current, t...

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Abstract

An avalanche photodiode including a first electrode; and a substrate including a first semiconductor layer of a first conduction type electrically connected to the first electrode, in which at least an avalanche multiplication layer, a light absorption layer, and a second semiconductor layer of a second conduction type with a larger band gap than the light absorption layer are deposited on the substrate. The second semiconductor layer is separated into inner and outer regions by a groove formed therein, the inner region electrically connected to a second. With the configuration, the avalanche photodiode has a low dark current and high long-term reliability. In addition, the outer region includes an outer trench, and at least the light absorption layer is removed by the outer trench to form a side face of the light absorption layer. With the configuration, the dark current can be further reduced.

Description

TECHNICAL FIELD[0001]This invention relates to a light receiving element using a semiconductor and in particular to an avalanche photodiode with low dark current and high reliability for the long term.BACKGROUND ART[0002]An avalanche photodiode, which is used for optical communications or the like, is a semiconductor light receiving element including, in addition to a layer for performing photoelectric conversion, a layer for performing avalanche multiplication of photoelectric converted carriers, which achieves enhanced light reception sensitivity; it is required for the avalanche photodiode to have a low dark current property and high reliability.[0003]Most of the avalanche photodiodes are formed of a compound semiconductor and can be roughly classified into a mesa structure and a planar structure according to its structure. The mesa structure is a structure in which a mesa is formed on a substrate and a pn junction is contained in the mesa. However, a breakdown easily occurs on t...

Claims

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Application Information

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IPC IPC(8): H01L31/0336
CPCH01L31/1075Y02E10/544H01L31/184H01L31/0352Y02P70/50
Inventor YAGYU, EIJIISHIMURA, EITARONAKAJI, MASAHARU
Owner MITSUBISHI ELECTRIC CORP
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