CN115939232A - Photoelectric detector - Google Patents

Abstract

The application discloses photoelectric detector belongs to photoelectric detection technical field, include: the optical resonator, the micro lens and the first reflecting device; the optical resonant cavity comprises a light incidence surface, a bottom reflecting surface and an outer side wall positioned between the light incidence surface and the bottom reflecting surface; the first reflecting device is positioned on the surface of the light incidence surface; the first reflecting device is used for reflecting the external light rays reflected to the light ray incidence surface by the bottom reflecting surface back to the optical resonant cavity; the micro lens is positioned on one side surface of the first reflecting device, which faces away from the optical resonant cavity. This application gets into the light in the optical resonator through reflection to reduce this light and directly reflect back to the detector outside through the bottom plane of reflection of optical resonator, compare with prior art, can promote photoelectric detector's photon absorption efficiency effectively.

Description

Photoelectric detector

Technical Field

The application relates to the technical field of photoelectric detection, in particular to a photoelectric detector.

Background

With the development of information technology, optical signals become the main carrier for propagating information. A photodetector is widely used in an optoelectronic system as a component capable of performing photoelectric conversion. However, in the prior art, when the surface reflection of the photodetector is high, the light is easily reflected back and forth with a matched receiving lens or filter for many times, and then is received by the photodetector, so that signal interference is caused, the light absorption efficiency of the photodetector is low, and the performance of the product is directly affected. Therefore, it is desirable to provide a photodetector to solve the problem of low light absorption efficiency of the existing photodetector.

Disclosure of Invention

It is an object of the present application to provide a photodetector, thereby improving photon absorption efficiency.

To achieve the above object, the present application provides a photodetector comprising: the optical resonator, the micro lens and the first reflecting device;

the optical resonant cavity comprises a light incidence surface, a bottom reflecting surface and an outer side wall positioned between the light incidence surface and the bottom reflecting surface;

the first reflecting device is positioned on the surface of the light incidence surface; the first reflecting device is used for reflecting the external light rays reflected to the light ray incidence surface by the bottom reflecting surface back to the optical resonant cavity;

the micro lens is positioned on one side surface of the first reflecting device, which faces away from the optical resonant cavity.

Optionally, the first reflecting means is a metal reflector.

Optionally, the length of the first reflecting device matches an included angle between an incident light ray and a surface normal of the microlens.

Optionally, the length of the first reflecting means matches the curvature of the microlens.

Optionally, the photodetector further includes: a second reflecting means;

the second reflecting device is a nanostructure layer and is positioned on the surface of the bottom reflecting surface.

Optionally, the surface of the microlens comprises a double-sided antireflection film.

Optionally, the photodetector further includes: a passivation layer;

the passivation layer is located between the micro lens and the optical resonant cavity.

Optionally, the photodetector further includes: a spacer layer;

the spacing layer is located between the micro lens and the passivation layer and is made of the same material as the micro lens.

Optionally, the length of the first reflecting means and the thickness of the spacer layer are matched.

Optionally, the photodetector further includes: a layer of antireflective material;

the anti-reflective material layer is located on the surface of the micro lens or between the spacing layer and the passivation layer.

The application provides a photoelectric detector, includes: the optical resonator, the micro lens and the first reflecting device; the optical resonant cavity comprises a light incidence surface, a bottom reflecting surface and an outer side wall positioned between the light incidence surface and the bottom reflecting surface; the first reflecting device is positioned on the surface of the light incidence surface; the first reflecting device is used for reflecting the external light rays reflected to the light ray incidence surface by the bottom reflecting surface back to the optical resonant cavity; the micro lens is positioned on one side surface of the first reflecting device, which faces away from the optical resonant cavity.

Obviously, this application gets into the light in the optical resonator through the reflection to reduce this light and directly reflect back to the detector outside through the bottom plane of reflection of optical resonator, compare with prior art, can promote photoelectric detector's photon absorption efficiency effectively.

Drawings

In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings needed to be used in the description of the embodiments or the prior art will be briefly introduced below, it is obvious that the drawings in the following description are only embodiments of the present application, and for those skilled in the art, other drawings can be obtained according to the provided drawings without creative efforts.

Fig. 1 is a schematic longitudinal sectional view of a structure of a photodetector according to an embodiment of the present application;

FIG. 2 is a schematic diagram of a focal point position under different refractive indexes of a lens according to an embodiment of the present application;

FIG. 3 is a schematic longitudinal cross-sectional view of another structure of a photodetector according to an embodiment of the present application;

fig. 4 is a schematic longitudinal cross-sectional view of another structure of a photodetector according to an embodiment of the present application.

In the accompanying fig. 1, 3, 4, the reference numerals are explained as follows:

101a, 101b, 101 c-light beam;

102-a microlens;

103-a spacer layer;

104-a passivation layer;

105. 106-first reflecting means;

107-second reflecting means;

108-a light absorbing layer;

109-outer side wall;

length of L-light absorbing layer;

l1-the length of the first reflecting device 106;

l2-length of first reflecting device 105;

s-thickness of the optical resonant cavity;

theta-angle of the beams 101a, 101b, and 101c with respect to the normal of the photodetector surface.

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application, and it is obvious that the described embodiments are some embodiments of the present application, but not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application.

In the prior art, when the surface reflection of the photoelectric detector is high, light easily forms multiple back and forth reflections with a matched receiving lens or filter (filter), and then is received by the photoelectric detector, so that signal interference is caused, and the performance of a product can be directly influenced. Therefore, the application provides a photoelectric detector, through setting up first reflect meter, the light reflection that will get into in the optical resonator returns optical resonator, can reduce light and camera lens multiple reflection on the one hand, causes signal interference, on the other hand promotes photoelectric detector's photon absorption efficiency effectively.

Referring to fig. 1, fig. 1 is a schematic longitudinal cross-sectional view of a structure of a photodetector provided in an embodiment of the present application, where the photodetector may include: an optical resonator, a microlens 102 and first reflecting means 105 and 106; the optical cavity comprises a light incident surface and a bottom reflecting surface, and an outer side wall 109 between the light incident surface and the bottom reflecting surface; the first reflecting means 105 and 106 are located on the surface of the light incidence plane; the first reflecting devices 105 and 106 are used for reflecting the external light rays reflected by the bottom reflecting surface to the light ray incidence surface back to the optical resonant cavity; the microlens 102 is located on a side surface of the first reflecting means 105 and 106 facing away from the optical cavity.

The light absorption layer 108 is formed in a region surrounded by the light incident surface, the bottom reflecting surface, and the outer wall 109, and the light absorption layer 108 is used for detecting an optical signal incident on the photodetector. The present embodiment does not limit the specific configuration of the light absorption layer 108, as long as it can be used for detecting the optical signal incident on the photodetector, and for example, the light absorption layer 108 may be formed of a photodiode.

The present embodiment does not limit the specific kind of the first reflecting devices 105 and 106 as long as the external light reflected from the bottom reflecting surface to the light incident surface can be reflected back to the optical cavity, and for example, the first reflecting devices 105 and 106 may be metal reflectors. The present embodiment does not limit the specific composition of the metal reflector, and for example, the metal reflector may be made of an aluminum material, a metal/oxide material, or a semiconductor material.

Further, in order to accommodate the light beams 101a, 101b and 101c incident from different angular positions and block as many non-light incident area openings as possible while not blocking the effective light beams from entering the light absorption layer 108, the lengths of the first reflecting devices 105 and 106 and the included angle between the incident light and the surface normal of the microlens 102 are matched in this embodiment.

Note that the curvature of the microlenses 102 is different, resulting in different lengths of the effective light beam incident area openings. Further, in order to shield the opening of the non-light incidence region as much as possible while not shielding the effective light beam from entering the light absorption layer 108, the lengths of the first reflecting means 105 and 106 in the present embodiment are matched with the curvature of the microlens 102. It can be understood that the photodetector is a three-dimensional structure, the shape of the opening of the incident region can be circular, rectangular or polygonal when viewed from the top, and the first reflecting device can be rectangular, polygonal or the like matching the shape of the opening. The size of the first reflecting device matches with the size of the opening, and those skilled in the art can easily think how to set the width of the first reflecting device, and the detailed description is omitted here.

Further, in order to improve the photon absorption efficiency of the photodetector, the embodiment may further include: a second reflecting means 107; the second reflecting device 107 is a nanostructure layer and is located on the surface of the bottom reflecting surface. The present embodiment does not limit the specific shape of the nanostructure layer, and for example, the nanostructure layer may be formed by regular triangle or inverted triangle sawtooth waveform in an array distribution, or other shape combinations that can form a specific reflection angle with light.

It is noted that the microlens 102 is used to focus incident light onto the active region of the epitaxial material inside the resonant cavity. Further, in order to increase the light transmission effect, the surface of the microlens 102 in the present embodiment includes a double-sided antireflection film.

Further, in order to provide passivation protection, the present embodiment may further include: a passivation layer 104; the passivation layer 104 is located between the microlens 102 and the optical resonant cavity. The present embodiment does not limit the specific composition of the passivation layer 104, and may be formed of one or more passivation materials, and the present embodiment does not limit the specific kind of the passivation material, for example, the passivation material may be an oxide material, a high-K dielectric material, a nitride material, or a polyimide material.

The present embodiment does not limit the specific way of fabricating the micro-lens 102, for example, the micro-lens 102 may be monolithically integrated or made of an optical material mechanically attached to the passivation layer 104.

Note that the thickness of the spacer layer 103 is different, resulting in different lengths of the openings of the effective light beam incident regions. Further, in order to adjust the length of the effective light beam incident area opening, the embodiment may further include: a spacer layer 103; the spacer layer 103 is located between the microlens 102 and the passivation layer 104, and is made of the same material as the microlens 102. The spacer layer 103 may be made of the same material as the microlens 102, and in this case, the spacer layer 103 may be regarded as a part of the microlens 102. Further, in order to shield the opening of the non-light incidence region as much as possible while not shielding the effective light beam from entering the light absorption layer 108, the lengths of the first reflecting means 105 and 106 in the present embodiment are matched with the thickness of the spacer layer 103.

Further, in order to improve the photon absorption efficiency of the photodetector, the embodiment may further include: a layer of antireflective material; a layer of antireflective material is located between the surface or spacer layer 103 of the microlens 102 and the passivation layer.

The present embodiment does not limit the specific kind of the anti-reflection layer, and may be any optical material, for example, any one or any combination of oxide, nitride or metal oxide.

It should be noted that matte surface treatment is performed to facilitate photon scattering and reflection. Further, in order to scatter and reflect more optical signals to the light absorbing layer 108, enhancing photon capturing capability, and thus improving photon absorption efficiency, the first reflecting means 105 and 106 and the second reflecting means 107 in this embodiment comprise matte surfaces.

The specific structure of the outer sidewall is not limited in this embodiment, and can be determined according to actual requirements, for example, the outer sidewall can be a deep trench isolation structure.

Based on above-mentioned embodiment, this application gets into the light in the optical resonator through reflection to reduce this light and directly reflect outside the detector through the bottom plane of reflection of optical resonator, compare with prior art, can promote photoelectric detector's photon absorption efficiency effectively.

Referring to fig. 1, fig. 2, fig. 3 and fig. 4, fig. 1 is a schematic longitudinal sectional view of a structure of a photodetector according to an embodiment of the present disclosure; FIG. 2 is a schematic diagram of a focal point position under different refractive indexes of a lens according to an embodiment of the present application; FIG. 3 is a schematic longitudinal cross-sectional view of another structure of a photodetector according to an embodiment of the present application; fig. 4 is a schematic longitudinal cross-sectional view of another structure of a photodetector provided in an embodiment of the present application, where the photodetector specifically includes: an optical resonator, a microlens 102, a passivation layer 104, a spacer layer 103, first reflective means 105 and 106, and second reflective means 107; the optical resonant cavity comprises a light incident surface and a bottom reflecting surface, and an outer side wall 109 positioned between the light incident surface and the bottom reflecting surface; a light absorption layer 108 is formed in an area surrounded by the light incidence surface, the bottom reflection surface and the outer side wall 109, and the light absorption layer 108 is used for detecting an optical signal incident to the photoelectric detector; the first reflecting devices 105 and 106 are positioned on the surface of the light incidence surface; the first reflecting devices 105 and 106 are used for reflecting the external light rays reflected by the bottom reflecting surface to the light ray incidence surface back to the optical resonant cavity; the microlens 102 is located on a side surface of the first reflecting means 105 and 106 facing away from the optical cavity. The second reflecting device 107 is a nanostructure layer and is located on the surface of the bottom reflecting surface. The passivation layer 104 is located between the microlens 102 and the optical resonant cavity. The spacer layer 103 is located between the microlens 102 and the passivation layer 104, and is made of the same material as the microlens 102. When the light beams 101a, 101b and 101c are incident perpendicularly to the photodetector surface, the first reflecting means may be symmetrically disposed along the optical axis of the microlens 102, i.e., the length L1 of the first reflecting means 106 is the same as the length L2 of the first reflecting means 105, i.e., has the same blocking range. Referring to fig. 1, in the present embodiment, light entering the optical resonant cavity is reflected to reduce the light from being directly reflected to the outside of the detector by the bottom reflecting surface of the optical resonant cavity.

Referring to fig. 2, (a) in the case where the curvature of the surface of the microlens 102 is large, the focal point of the light converging in the optical cavity is high; (b) When the curvature of the surface of the micro lens 102 is smaller, the focus of the light rays polymerized in the optical resonant cavity is lower; (c) In the case where the curvature of the surface of the microlens 102 is the same as that of (b) but the thickness of the spacer layer 103 is large, the focal point of the light converged in the optical cavity is high. By contrast, it can be seen that the thickness S of the optical cavity can be set smaller with a larger curvature. In addition, when the curvature is constant and the thickness of the spacer layer 103 is large, the thickness S of the optical cavity may be set small.

Referring to fig. 3, (b) is the case where the curvature of the surface of the microlens 102 is small, and the length of the opening of the incident region is large, the focal point of the light converging in the optical resonator is low; (c) In the case where the curvature of the surface of the microlens 102 is large and the thickness of the spacer layer 103 is large, the length of the opening of the incident region is small, and the focal point of the light converging in the optical resonant cavity is high. By contrast, fig. 1 corresponds to a microlens with small curvature, and fig. 3 (a) corresponds to a microlens with large curvature, it can be seen that when the curvature is large and the thickness of the spacer layer 103 is large, the length of the incident region opening is small, and the lengths of the first reflection devices 105 and 106 need to be set long; the thickness of the optical resonator is small.

When the curvature of the surface of the microlens 102 is larger, or the thickness of the curvature-invariant spacer layer 103 is larger, the length of the effective beam incident region opening is smaller, and therefore it is necessary to provide a larger size of the shielding range, that is, the length L1 of the first reflecting device 106 and the length L2 of the first reflecting device 105 are increased (L1 = L2> 1/3L), and a thinner optical resonator, that is, the thickness S of the optical resonator is reduced.

Referring to fig. 4, when the light beams 101a, 101b, and 101c have an angle θ with the normal of the surface of the photodetector, (b) is a light path diagram of the light entering the photodetector after passing through the microlens when θ is 15 degrees; (c) When theta is 10 degrees, light enters the optical path diagram of the photoelectric detector after passing through the micro lens; it can be seen that when θ is 0, the lengths of the lengths L2 and L1 of the first reflecting device 105 and 106 are the same, when L2= L1 and when θ is not 0, the lengths of the lengths L2 and L1 of the first reflecting device 105 and 106 are different, when L2> L1. In contrast, when the curvature of the microlens is the same as that of fig. 4 (B) and fig. 4 (C), the length of the opening in the incident area is the same, but the included angle is larger, and the opening is more deviated to the left side, i.e., the length L1 (B) < L1 (C) of the left first reflection device 106, and the length L2 (C) > L2 (B) of the right first reflection device 105. Of course, the light may also be incident from the left, which is only illustrated here as an example of the light from the right.

The photodetector array comprises 10-10000 photodetector cells. The photoelectric detector unit is opposite to the laser, which is equivalent to the vertical incidence of light; the side faces the laser, which is equivalent to the light with an included angle. The length L1 of the first reflecting means 106 and the length L2 of the first reflecting means 105 will also be different for different photodetector unit positions. When the light beams 101a, 101b and 101c have an angle θ with the normal of the surface of the photodetector, the length L2 of the first reflecting device 106 and the length L1 of the first reflecting device 105 should be matched with each other as the edge light beam is incident.

The principle and the implementation of the present application are described herein by applying specific examples, and in order to make the various embodiments have a progressive relationship, each embodiment focuses on the differences from the other embodiments, and the same and similar parts among the various embodiments may be referred to each other. The above description of the embodiments is only intended to help understand the method of the present application and its core ideas. It will be apparent to those skilled in the art that various changes and modifications can be made in the present invention without departing from the principles of the invention, and these changes and modifications also fall within the scope of the claims of the present application.

It is further noted that, in the present specification, relational terms such as first and second, and the like are used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Also, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrases "comprising a component of' 8230; \8230;" does not exclude the presence of additional identical elements in the process, method, article, or apparatus that comprises the element.

Claims (10)

1. A photodetector, comprising: the optical resonator, the micro lens and the first reflecting device;

the optical resonant cavity comprises a light incidence surface, a bottom reflecting surface and an outer side wall positioned between the light incidence surface and the bottom reflecting surface;

the first reflecting device is positioned on the surface of the light incidence surface; the first reflecting device is used for reflecting the external light rays reflected to the light ray incidence surface by the bottom reflecting surface back to the optical resonant cavity;

the micro lens is positioned on one side surface of the first reflecting device, which faces away from the optical resonant cavity.

2. The photodetector of claim 1, wherein the first reflecting means is a metal reflector.

3. The photodetector of claim 1, wherein the length of the first reflecting means matches the angle of the incident ray to the surface normal of the microlens.

4. The photodetector of claim 1, wherein the length of the first reflecting means matches the curvature of the microlens.

5. The photodetector of claim 1, further comprising: a second reflecting means;

the second reflecting device is a nanostructure layer and is positioned on the surface of the bottom reflecting surface.

6. The photodetector of claim 1, wherein a surface of the microlens comprises a double-sided anti-reflective film.

7. The photodetector of claim 1, further comprising: a passivation layer;

the passivation layer is located between the micro lens and the optical resonant cavity.

8. The photodetector of claim 7, further comprising: a spacer layer;

the spacing layer is located between the micro lens and the passivation layer and is made of the same material as the micro lens.

9. The photodetector of claim 8 wherein the length of the first reflecting means matches the thickness of the spacer layer.

10. The photodetector of claim 8, further comprising: a layer of antireflective material;

the layer of antireflective material is located on a surface of the microlens or between the spacer layer and the passivation layer.

Images