CN106688109A - Photoelectric detector - Google Patents

Abstract

A photodetector, comprising: a substrate (11), a bulk insulating layer (12) disposed above the substrate (11), a first doped layer (13) disposed above the bulk insulating layer (12), the first doped layer A second doped layer (14) is arranged above the heterogeneous layer (13), and a cladding insulating layer (17) is arranged above the second doped layer (14); one end of the first metal electrode (15) is arranged inside the first doped layer (13), the other end of the first metal electrode (15) passes through the cladding insulating layer (17) and constitutes the first electrode lead; one end of the second metal electrode (16) is arranged inside the second doped layer (14), the second The other end of the two metal electrodes (16) passes through the clad insulating layer (17) and constitutes a second electrode lead; the second doped layer (14) expands outwards at least one extension (18), and the at least one extension ( 18) Embedded in the first doped layer (13), the material of the at least one extension (18) and the second doped layer (14) are the same; wherein, the first doped layer (13) is P When the doped layer is an N-type doped layer, the second doped layer (14) is an N-type doped layer; when the first doped layer (13) is an N-type doped layer, the second doped layer (14) is a P-type doped layer Floor. The photodetector improves the photoelectric conversion rate.

Description

a photodetector technical field

The invention relates to the technical field of detectors, in particular to a photoelectric detector.

Background technique

Photodetectors are used to convert optical signals into electrical signals, that is, a device that can convert optical radiation energy into a physical quantity that is easy to measure. It is widely used in optical communication, optical interconnection, optical signal processing and other technical fields, especially Highly integrated photodetectors based on semiconductor materials such as silicon and germanium will be indispensable key devices for future ultra-small optical interconnection systems. At present, there are many photodetector structures, including the commonly used PN structure and PIN structure, etc. The technical indicators for measuring photodetectors include response bandwidth, sensitivity, power consumption, photoelectric conversion efficiency, etc. Among them, photoelectric conversion efficiency is the photoelectric conversion efficiency. The important performance parameters of the detector are used to describe the efficiency of converting incident photons into electrons, and its level directly affects the effective reception of signals. Therefore, the photoelectric conversion efficiency has become one of the important considerations for various manufacturers when producing photodetectors.

Contents of the invention

An embodiment of the present invention provides a photodetector for improving the photoelectric conversion rate.

The first aspect of the present invention provides a photodetector, including: a substrate, a bulk insulating layer, a first doped layer, a second doped layer, a first metal electrode, a second metal electrode, and a cladding insulating layer;

The bulk insulating layer is disposed above the substrate, the first doped layer is disposed above the bulk insulating layer, the second doped layer is disposed above the first doped layer, and the second doped layer is disposed above the first doped layer. The cladding insulating layer is arranged above the layer;

One end of the first metal electrode is arranged inside the first doped layer, and the other end of the first metal electrode passes through the cladding insulating layer and constitutes a first electrode lead; one end of the second metal electrode is arranged in the Inside the second doped layer, the other end of the second metal electrode passes through the cladding insulating layer and forms a second electrode lead;

The second doped layer extends outwards with at least one extension, the at least one extension is embedded in the first doped layer, and the at least one extension is made of the same material as the second doped layer;

Wherein, when the first doped layer is a P-type doped layer, the second doped layer is an N-type doped layer; When the first doped layer is an N-type doped layer, the second doped layer is a P-type doped layer.

With reference to the first aspect, in a first possible implementation manner, when the first doped layer is a P-type doped layer and the second doped layer is an N-type doped layer, the first metal electrode is a P-type source, and the second metal electrode is an N-type drain.

With reference to the first aspect, in a second possible implementation manner, when the first doped layer is an N-type doped layer and the second doped layer is a P-type doped layer, the first metal electrode is an N-type drain, and the second metal electrode is a P-type source.

In combination with the first aspect, or the first possible implementation of the first aspect, or the second possible implementation of the first aspect, in a third possible implementation, the photodetector further includes an intrinsic region, wherein the intrinsic region is disposed between the contact surfaces of the first doped layer and the second doped layer.

With reference to the third possible implementation manner of the first aspect, in a fourth possible implementation manner, in a state where the extension of the second doped layer is embedded in the first doped layer, the The intrinsic region leans toward the first doped layer at a corresponding position of the extension to form a concave shape, and the concave shape matches the shape of the extension.

It can be seen that the photodetector provided by the embodiment of the present invention includes a stacked substrate 11, a bulk insulating layer 12, a first doped layer 13, a second doped layer 14, and a cladding insulating layer 17. Layer 14 has at least one extension 18 extending outward, and the extension 18 is embedded in the first doped layer 13, wherein at least one extension 18 is made of the same material as the second doped layer 14, therefore, in the first A PN junction is formed at the contact surface between the doped layer 13 and the second doped layer 14, and at the contact surface between the first doped layer 13 and the extension body 18 of the second doped layer 14, that is, the first doped layer 13 The PN junction is not only formed on the lateral contact surface with the second doped layer 14, but also the second doped layer 14 forms a PN junction with the first doped layer 13 in the vertical direction through the extension body 18, effectively increasing the photoelectricity. The effective area of the PN junction in the detector, then, apply a reverse bias voltage to the first metal electrode 15 that is arranged on the first doped layer 13 at one end, and apply a reverse bias voltage to the second metal electrode 16 that is arranged on the second doped layer 14 at one end After the reverse bias voltage is applied, the incident light is incident on the PN junction from the cladding insulating layer 17, and the electrons on the PN junction transition after absorbing the energy of the incident light, and excite photogenerated carriers, which are transferred to the first metal electrode 15 Under the action of the electric field formed by the second metal electrode 16, the light energy is converted into an electric signal. In the embodiment of the present invention, the photoelectric conversion rate is improved by increasing the area of the PN junction.

Description of drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following will briefly introduce the accompanying drawings that are required for the description of the embodiments. Obviously, the accompanying drawings in the following description are only some embodiments of the present invention. Those of ordinary skill in the art can also obtain other drawings based on these drawings without any creative effort.

Fig. 1 is the side dissection diagram of the photodetector provided by the embodiment of the present invention;

2 is a schematic diagram of the working principle of the photodetector provided by the embodiment of the present invention;

3 is a schematic diagram of the working principle of a photodetector provided by another embodiment of the present invention;

4 is a side profile view of a photodetector with a PIN junction structure provided by some embodiments of the present invention;

FIG. 5 is a top view of a photodetector with a PN junction structure provided by some embodiments of the present invention.

detailed description

In order to make the purpose, features and advantages of the present invention more obvious and understandable, the following will describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the embodiments described below It is only some embodiments of the present invention, but not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without making creative efforts belong to the protection scope of the present invention.

The terms "first" and "second" in the specification and claims of the present invention and the above drawings are used to distinguish different objects, rather than to describe a specific order. Furthermore, the terms "comprising" and "having", as well as any variations thereof, are intended to cover a non-exclusive inclusion. For example, a process, method, system, product or device comprising a series of steps or units is not limited to the listed steps or units, but optionally also includes unlisted steps or units, or optionally further includes For other steps or units inherent in these processes, methods, products or apparatuses.

An embodiment of the present invention provides a photodetector for improving the photoelectric conversion rate. Wherein, the photodetector provided by the embodiment of the present invention can be applied to an optical interconnection system, an optical communication system, or an optical signal processing system, and the like.

The photodetector provided by the embodiment of the present invention will be described in detail below with reference to FIGS. 1 to 5 . Among them, Fig. 1 is a side profile view of the photodetector provided by the embodiment of the present invention. As shown in Fig. 1, the photodetector provided by some embodiments of the present invention may include:

Substrate 11, bulk insulating layer 12, first doped layer 13, second doped layer 14, first metal electrode 15. The second metal electrode 16 and the cladding insulating layer 17;

The bulk insulating layer 12 is disposed above the substrate 11, the first doped layer 13 is disposed above the bulk insulating layer 12, and the second doped layer 14 is disposed above the first doped layer 13, The cladding insulating layer 17 is disposed above the second doped layer 14;

One end of the first metal electrode 15 is arranged inside the first doped layer 13, and the other end of the first metal electrode 15 passes through the cladding insulating layer 17 and constitutes a first electrode lead; the second metal One end of the electrode 16 is disposed inside the second doped layer 14, and the other end of the second metal electrode 16 passes through the cladding insulating layer 17 and constitutes a second electrode lead;

The second doped layer 14 extends outwards at least one extension 18, the at least one extension 18 is embedded in the first doped layer 13, the at least one extension 18 and the second doped The material of layer 14 is the same;

Wherein, when the first doped layer 13 is a P-type doped layer, the second doped layer 14 is an N-type doped layer; when the first doped layer 13 is an N-type doped layer, the The second doped layer 14 is a P-type doped layer.

It can be seen that in the photodetector provided by the embodiment of the present invention, the substrate 11, the bulk insulating layer 12, the first doped layer 13, the second doped layer 14, and the cladding insulating layer 17 are of a stacked design, wherein, The second doped layer 14 extends outwards with at least one extension 18, the at least one extension 18 is embedded in the first doped layer 13, and the material of at least one extension 18 is the same as that of the second doped layer 14 , therefore, a PN junction is formed at the contact surface of the first doped layer 13 and the second doped layer 14, and at the contact surface of the extension body 18 of the first doped layer 13 and the second doped layer 14, namely The first doped layer 13 and the second doped layer 14 not only form a PN junction on the lateral contact surface, but also form a PN junction with the first doped layer 13 in the vertical direction through the extension body 18 . Junction, effectively increasing the effective area of the PN junction in the photodetector, thereby increasing the number of photogenerated carriers generated per unit incident light window area. Therefore, the first metal electrode 15 disposed on the first doped layer 13 at one end After applying a reverse bias voltage and applying a reverse bias voltage to the second metal electrode 16 with one end disposed on the second doped layer 14, the incident light is incident on the PN junction in the lateral and vertical directions from the cladding insulating layer 17, and the PN junction After absorbing the energy of the incident light, the electrons on the surface transition, excite the photogenerated carriers, and convert them into electrical signals under the action of the electric field formed by the first metal electrode 15 and the second metal electrode 16, which improves the photoelectric conversion rate.

The working principle of the photodetector provided in FIG. 1 will be briefly introduced below. Please refer to Figure 2, Figure 2 is a schematic diagram of the working principle of the photodetector provided by the embodiment of the present invention; as shown in Figure 2, 21 is the contact surface between the first doped layer 13 and the second doped layer 14 and the 13 and the PN junction formed on the contact surface of the extension body 18 of the second doped layer 14, when the photodetector is working, a reverse bias voltage is applied to the PN junction through the first metal electrode 15 and the second metal electrode 16, and the incident light is transmitted from When the cladding insulating layer 17 is incident, when the incident light is incident on the PN junction, the electrons in the PN junction area transition after absorbing the energy of the incident light, and excite photogenerated carriers, which are converted into electrical signals under the action of an electric field.

It can be seen from FIG. 2 that in the embodiment of the present invention, the first doped layer 13 and the second doped layer 14 form a PN junction at the lateral contact surface, and the extension body 18 of the first doped layer 13 and the second doped layer 14 The PN junction is also formed in the contact surface in the vertical direction, thereby increasing the total area of the PN junction as a whole, so that the number of photogenerated carriers generated per unit area of the incident light window is larger, and the photoelectric conversion efficiency is improved.

In addition, from the perspective of response rate, since the response rate of the photodetector is mainly related to the transition time of photogenerated carriers, in the embodiment of the present aspect, the width of the PN junction does not increase significantly, so the response rate of the photodetector is Has little effect. From the perspective of power consumption, since lower reverse bias voltage can obtain higher photoelectric conversion efficiency, it can be applied to scenarios with low power consumption requirements.

The working principle of the photodetector provided in Fig. 1 will be further analyzed below. In conjunction with Figure 2, please refer to Figure 3, Figure 3 is a schematic diagram of the working principle of the photodetector provided by another embodiment of the present invention; Figure 3 further introduces the working principle of the photodetector provided by the embodiment of the present invention on the basis of Figure 2 . It can be seen in FIG. 3 that since the extension 18 of the second doped layer 14 is embedded in the first doped layer 13, the contact between the first doped layer 13 and the extension 18 of the second doped layer 14 A PN junction region perpendicular to the first doped layer 13 is formed on the surface. When the photodetector is working, the incident light changes periodically in the vertical PN junction region, which can form a grating-like light diffraction effect. The direction of travel will be diffracted from the vertical direction to the horizontal direction (as shown by the arrow in Figure 3), which is conducive to the further absorption of incident light, achieving higher absorption efficiency, and further improving the photoelectric conversion efficiency of the photodetector.

It can be understood that the above-mentioned Figures 1 to 3 are descriptions of photodetectors with a PN junction structure. On the basis of the above-mentioned photodetectors with a PN junction structure, an embodiment of the present invention also provides a photodetector with a PIN junction structure , as shown in FIG. 4, compared with the photodetector of the PN junction structure shown in FIG. Between the contact surface of the impurity layer 13 and the second doped layer 14 .

That is to say, in a photodetector with a PIN junction structure, the intrinsic region 19 is used to isolate the first doped layer 13 and a second doped layer 14.

In a state where the extension body 18 is embedded in the first doped layer 13 , the intrinsic region 19 at the corresponding position of the extension body 18 tends toward the first doped layer 13 to form a concave shape. Wherein, the concave shape matches the shape of the extension body 18 .

It can be understood that the intrinsic region 19 is an undoped region or a region with a low doping concentration, and the material used in it is close to the intrinsic region. When a reverse bias voltage is applied, the entire intrinsic region is a depletion layer, and both It can be used to absorb incident light to generate photogenerated carriers.

Based on the above introduction, in the photodetector of the PIN junction structure provided in FIG. 4, the intrinsic region 19 is used to isolate between the first doped layer 13 and the second doped layer 14, and the entire intrinsic region 19 is used as a depletion layer. Used to absorb incident light and generate photocarriers. Therefore, in the photodetector of PIN junction structure, the contact surface of the first doped layer 13 and the intrinsic region 19, the contact surface of the second doped layer 14 and the intrinsic region 19, and the entire intrinsic region 19 serve as the PIN junction. , the PIN junction replaces the PN junction in the PN junction structure. Wherein, the working principle of the photodetector of the PIN junction structure is as follows: when the photodetector of the PIN junction structure is working, the reverse bias voltage is applied to the PIN junction through the first metal electrode 15 and the second metal electrode 16, and the incident light passes through the cladding layer The insulating layer 17 is incident, and when the incident light is incident on the PIN junction, the electrons in the PIN junction area transition after absorbing the energy of the incident light, excite photogenerated carriers, and convert them into electrical signals under the action of an electric field.

Because in the photodetector of the PIN junction structure shown in FIG. The first doped layer 13 tends to be in a concave shape, therefore, a PIN junction region is also formed in the direction perpendicular to the first doped layer 13, thereby increasing the total area of the PIN junction as a whole, so that the unit incident light window area The number of photogenerated carriers generated is more, and the photoelectric conversion efficiency is improved.

In addition, because the incident light changes periodically in the vertical PIN junction region, a grating-like light diffraction effect can be formed, and the traveling direction of the light will be diffracted from the vertical direction to the horizontal direction, which is conducive to the further absorption of the incident light and realizes more The high absorption efficiency further improves the photoelectric conversion efficiency of the photodetector.

It should be noted that, in the embodiment of the present invention, the second doped layer 14 and the extension body 18 are doped from the same material, forming an integral structure.

In some practicable manners of the present invention, when producing the photodetector, the substrate 11 is first formed on the bottom, and then the body insulating layer 12 is formed on the substrate 11, and the first doped doped layer is formed on the body insulating layer 12. impurity layer 13, after the first doped layer 13 is completed, at least one region is etched in the first doped layer 13, and then a second doped layer is formed on the surface of the first doped layer 13 by selective growth 14 and an extension 18 is formed in this region. For example, if the first doped layer 13 is a P-type doped layer and the second doped layer 14 is an N-type doped layer, when producing the photodetector, the substrate 11 is first formed at the bottom, and then A body insulating layer 12 is formed on the bottom 11, and then a layer of semiconductor silicon is formed on the body insulating layer 12, and then boron is doped into the semiconductor silicon to form a P-type doped layer, and then, by etching, the At least one region is etched on the P-type doped layer, and then a layer of semiconductor silicon is formed above the P-type doped layer and in this region, and phosphorus is doped into the semiconductor silicon to form an N-type doped layer. In the etched region, an extension body 18 in which the N-type doped layer expands outward is obtained.

In other practicable manners of the present invention, when producing the photodetector, the substrate 11 is first formed at the bottom, and then the body insulating layer 12 is formed above the substrate 11, and the first doped layer 13, the second doped layer The impurity layer 14 and the extended extension body 18 can be formed by defining different photolithographic regions, then respectively performing ion implantation in the corresponding photolithographic regions and activating them by rapid high temperature annealing.

Optionally, the extension body 18 may be a geometric body of any shape, such as a cylinder, a pyramid, a platform, a cuboid, and the like. Therefore, when producing photodetectors, if the extension body 18 of the second doped layer 14 is formed by etching a region in the first doped layer 13, the shape of the etched region is correspondingly columnar. body, vertebral body, table body, cuboid, etc. Similarly, if the method of first defining different photolithographic regions is adopted, the photolithographic regions where the extension body 18 is located are correspondingly cylinders, pyramids, mesa bodies, cuboids, etc.

Wherein, in the embodiment of the present invention, the first metal electrode 15 can be a P-type source or an N-type drain, and correspondingly, the second metal electrode 16 can be an N-type drain or a P-type source, specifically including the following two cases :

A1, when the first doped layer 13 is a P-type doped layer, and the second doped layer 14 is an N-type doped layer, the first metal electrode 15 is a P-type source, and the second metal electrode 16 is an N-type Drain;

A2. When the first doped layer 13 is an N-type doped layer and the second doped layer 14 is a P-type doped layer, the first metal electrode 15 is an N-type drain, and the second metal electrode 16 is a P-type source pole.

Optionally, in the embodiment of the present invention, the second doped layer 14 in the photodetector is in the shape of a comb.

Wherein, the material of the first doped layer 13 is a semiconductor material, and the material of the second doped layer 14 is a semiconductor material. Optionally, the semiconductor material may be silicon, germanium or III-V compound material.

For example, please refer to FIG. 5. FIG. 5 is a top view of a photodetector with a PN junction structure provided by some embodiments of the present invention; in FIG. 5, the incident window of the photodetector with a PN junction structure according to an embodiment of the present invention is Circular structure, in Figure 5, the bottom of the photodetector of the PN junction structure is an N-type doped layer, the top is a P-type doped layer, and an annular N-type drain is formed outside the N-type doped layer. A ring-shaped P-type source is formed outside the N-type doped layer, and an electrode lead is drawn out from the N-type drain, and similarly, an electrode lead is drawn out from the P-type drain. The small circle in FIG. 5 is used to represent the extension 18 of the P-type doped layer, which is embedded in the N-type doped layer. In FIG. 5, 12 extensions 18 are taken as an example. After the light is incident from the circular incident window, the electrons at the PN junction absorb the energy of the incident light, convert it into an electrical signal, and then output the electrical signal from the P-type source and N-type drain.

It should be noted that FIG. 5 only shows an example of a photodetector with a PN junction structure, and the light incident window of the photodetector in the embodiment of the present invention may have other shapes besides the circular structure shown in FIG. 5 . For example, in the top view shown in FIG. 5 , the projected shape of the top view of the extension body 18 changes according to the actual shape of the extension body 18. For example, when the shape of the extension body 18 is a cylinder, the projection of the top view is circular as shown in FIG. 5 . When the shape of the extension body 18 is a three-sided cylinder, its projected shape in a top view is a triangle, which is not limited herein.

For example, the photodetector with a PN junction structure or the photodetector with a PIN junction structure provided in the above embodiments can be applied in an optical interconnection system. The photodetector is also connected to the external circuit through the P-type source and N-type drain, and the reverse bias voltage is applied to the PN junction or PIN junction in the photodetector through the external circuit, and the photoelectric detection The device starts to work, the incident light enters from the insulating layer, and when the incident light enters the PN junction or PIN junction, the photogenerated carriers are excited, and the electric signal is formed under the action of the electric field, passing through the P-type source and N-type drain Output to the optical receiving module, and the optical receiving module completes the subsequent operation on the electrical signal.

In summary, the photodetector provided by the embodiment of the present invention includes a stacked substrate 11, a bulk insulating layer 12, a first doped layer 13, a second doped layer 14, and a cladding insulating layer 17. The heterogeneous layer 14 expands at least one extension body 18 outward, and the extension body 18 is embedded in the first doped layer 13, wherein the material of at least one extension body 18 is the same as that of the second doped layer 14, therefore, in the A PN junction is formed at the contact surface between the first doped layer 13 and the second doped layer 14, and at the contact surface between the first doped layer 13 and the extension body 18 of the second doped layer 14, that is, the first doped layer 13 with the second doped layer 14 not only in the lateral A PN junction is formed on the contact surface of the photodetector, and the second doped layer 14 forms a PN junction with the first doped layer 13 in the vertical direction through the extension body 18, effectively increasing the effective area of the PN junction in the photodetector, then , after applying a reverse bias voltage to the first metal electrode 15 with one end disposed on the first doped layer 13 and applying a reverse bias voltage to the second metal electrode 16 disposed on the second doped layer 14 at one end, the incident light from the package The insulating layer 17 is incident on the PN junction, and the electrons on the PN junction transition after absorbing the energy of the incident light, excite the photogenerated carriers, and act on the electric field formed by the first metal electrode 15 and the second metal electrode 16 The light energy is converted into electrical signals, which improves the photoelectric conversion rate.

The photodetector provided by the embodiment of the present invention has been introduced in detail above. For those of ordinary skill in the art, according to the idea of the embodiment of the present invention, there will be changes in the specific implementation and application range. As mentioned above, the content of this specification should not be construed as limiting the embodiments of the present invention.

Claims (7)

1. A kind of photodetector, it is characterised in that including：Substrate (11), body insulating barrier (12), the first doped layer (13), the second doped layer (14), the first metal electrode (15), the second metal electrode (16) and covering insulating barrier (17)；

   Set the body insulating barrier (12), the body insulating barrier (12) top that first doped layer (13) is set above the substrate (11), set above first doped layer (13) and the covering insulating barrier (17) is set above second doped layer (14), second doped layer (14)；

   Described first metal electrode (15) one end is arranged on the first doped layer (13) inside, and the first metal electrode (15) other end is through the covering insulating barrier (17) and constitutes first electrode lead；Described second metal electrode (16) one end is arranged on the second doped layer (14) inside, and the second metal electrode (16) other end is through the covering insulating barrier (17) and constitutes second electrode lead；

   Second doped layer (14) propagates outward into a few ennation (18), at least one described ennation (18) is embedded in first doped layer (13), and at least one described ennation (18) is identical with the material of second doped layer (14)；

   Wherein, when first doped layer (13) is p-type doped layer, second doped layer (14) is n-type doping layer；When first doped layer (13) is n-type doping layer, second doped layer (14) is p-type doped layer.
2. Photodetector according to claim 1, it is characterised in that

   First doped layer (13) is p-type doped layer and when second doped layer (14) is n-type doping layer, and first metal electrode (15) is p-type source electrode, and second metal electrode (16) is N-type drain.
3. Photodetector according to claim 1, it is characterised in that

   First doped layer (13) is n-type doping layer and when second doped layer (14) is p-type doped layer, and first metal electrode (15) is N-type drain, and second metal electrode (16) is p-type source electrode.
4. Photodetector according to any one of claims 1 to 3, it is characterised in that

   The photodetector also includes intrinsic region (19), wherein, the intrinsic region (19) is set between first doped layer (13) and the contact surface of the second doped layer (14).
5. Photodetector according to claim 4, it is characterised in that

   In the state of the ennation (18) of second doped layer (14) is embedded in first doped layer (13), it is in concave shape that the intrinsic region (19) is inclined to first doped layer (13) in the correspondence position of the ennation (18), and the concave shape matches the shape of the ennation (18).
6. Photodetector according to any one of Claims 1 to 5, it is characterised in that

   Second doped layer (14) is in comb form.
7. Photodetector according to any one of claim 1~6, it is characterised in that

   The material of first doped layer (13) is semi-conducting material, and the material of second doped layer (14) is semi-conducting material, and the semi-conducting material is silicon, germanium or III-V compound-material.