阅读说明：本技术 一种基于嵌入式光栅结构的窄带近红外热电子光电探测器 (Narrow-band near-infrared thermal electron photoelectric detector based on embedded grating structure ) 是由 张程 施嘉伟 李孝峰 刘添裕 曹诗嘉 眭博闻 蔡文杰 于 2019-09-29 设计创作，主要内容包括：本发明涉及光电传感技术领域,为解决现有技术中存在的光电探测器响应度不高的问题,提供一种基于嵌入式光栅结构的窄带近红外热电子光电探测器,包含硅基底和金属光栅；金属光栅和硅基底之间有一层钛薄膜作为粘附层；金属光栅连接到顶部导电电极；硅背面设有底部导电电极；通过将金属光栅嵌入在硅基底中的方式进一步地提高了金属的光吸收效率、热电子产生率,减少了热电子的热化损失,增加了光栅侧面的肖特基界面而提高了热电子转移到硅中的收集效率,进而提升了光电探测器的响应度；调节金属光栅周期可改变探测器的响应波长,实现了波长可调的近红外光电探测器。(The invention relates to the technical field of photoelectric sensing, and provides a narrow-band near-infrared thermal electron photoelectric detector based on an embedded grating structure, aiming at solving the problem of low responsivity of the photoelectric detector in the prior art, wherein the narrow-band near-infrared thermal electron photoelectric detector comprises a silicon substrate and a metal grating; a titanium film is arranged between the metal grating and the silicon substrate as an adhesion layer; the metal grating is connected to the top conductive electrode; a bottom conductive electrode is arranged on the back of the silicon; the metal grating is embedded into the silicon substrate, so that the light absorption efficiency and the hot electron generation rate of metal are further improved, the thermalization loss of hot electrons is reduced, a Schottky interface on the side surface of the grating is increased, the collection efficiency of hot electrons transferred into silicon is improved, and the responsivity of the photoelectric detector is further improved; the response wavelength of the detector can be changed by adjusting the period of the metal grating, and the near infrared photoelectric detector with adjustable wavelength is realized.)

1. A narrow-band near-infrared thermionic photoelectric detector based on an embedded grating structure is characterized in that,

comprises a silicon substrate, a titanium film, a metal grating, a top conductive electrode and a bottom conductive electrode; the titanium film and the metal grating are sequentially arranged on the silicon substrate; the bottom conductive electrode is connected to the silicon substrate, and the top conductive electrode is fixedly connected with the metal grating;

the titanium film is used as an adhesive layer to connect the silicon substrate and the metal grating;

the metal grating is embedded in the silicon substrate.

2. The narrow-band near-infrared thermionic photodetector based on an embedded grating structure as claimed in claim 1, wherein the metal grating is made of one or more metal alloys, metal nitrides, and metal oxides.

3. The embedded grating structure-based narrowband near-infrared thermionic photodetector of claim 1, wherein the bottom conductive electrode on the back side of the silicon substrate is one of indium and aluminum; the metal in the metal grating comprises: gold, silver, copper, aluminum.

4. The narrow-band near-infrared thermionic photodetector based on an embedded grating structure as claimed in claim 1, wherein the thickness of the metal grating is 100-400 nm.

5. The narrow-band near-infrared thermionic photodetector based on the embedded grating structure as claimed in claim 4, wherein the embedded depth of the metal grating embedded in the silicon substrate is 0-600 nm.

6. The narrow-band near-infrared thermionic photodetector based on the embedded grating structure as claimed in claim 5, wherein the thickness of the titanium thin film layer is 1-5 nm.

Technical Field

The invention relates to the technical field of photoelectric sensing, in particular to a narrow-band near-infrared thermal electron photoelectric detector based on an embedded grating structure.

Background

In planar metals, electrons absorb the energy of incident light, transition from the ground state to a higher energy level and are converted to hot electrons, a process known as photo-induced direct excitation. However, since the reflectivity of the planar metal is high, the generation efficiency of hot electrons is extremely low. Since the surface plasmon has a high local electric field enhancement effect, a process of generating thermal electrons by exciting the surface plasmon is increasingly receiving attention. In the metal nanostructure, electrons in the metal resonate with incident electromagnetic waves to excite surface plasmons, and generate thermal electrons in the form of electron transitions under the energy perturbation of the surface plasmons. In this way, the optical signal can be efficiently converted into an electrical signal by the photodetector. However, how to further improve the optical responsivity of the photodetector has been a great challenge.

In recent years, a special light transmission phenomenon is found in a periodic metal hole array structure, and surface plasmons are more efficiently generated and propagated on a metal surface through the metal hole array structure, the responsivity of a photoelectric detector under zero bias voltage can reach 0.6 mA/W by preparing a gold grating structure on a silicon substrate, and meanwhile, the period of the grating structure can be changed to adjust the light detection wavelength, for example (application number: CN 201110124310.0) in a silicon nanowire grating resonance enhanced photoelectric detector and a manufacturing method thereof, light is effectively concentrated to a sub-wavelength grating detection region by designing a periodic nano metal grating structure, so that the surface transmission and absorption of the light are enhanced, for example (application number: CN201810421809. X) in an absorption enhanced grating coupling type silicon-based photoelectric detector and a manufacturing method thereof, a periodic metal grating with a two-dimensional structure is adopted to be coupled with incident light, light is locally positioned on the surface of an active layer by utilizing an F-P resonance-like structure between a surface plasmon and a metal grating, so that the absorption of the photoelectric detector is enhanced, however, the light absorption efficiency of the metal grating structure is only limited by the conventional absorption of a Schottky grating structure is not beneficial to the formation of a Schottky grating structure (~ 50, and the conventional semiconductor structure is not beneficial to the improvement of the absorption efficiency of the conventional semiconductor structure).

Disclosure of Invention

In order to solve the problem of low responsivity of a photoelectric detector in the prior art, the invention provides a narrow-band near-infrared thermionic photoelectric detector based on an embedded grating structure, which adopts the following technical scheme:

a narrow-band near-infrared thermionic photoelectric detector based on an embedded grating structure comprises a silicon substrate, a titanium film, a metal grating, a top conductive electrode and a bottom conductive electrode; the titanium film and the metal grating are sequentially arranged on the silicon substrate; the bottom conductive electrode is connected to the silicon substrate, and the top conductive electrode is fixedly connected with the metal grating; the titanium film is used as an adhesive layer to connect the silicon substrate and the metal grating; the metal grating is embedded in the silicon substrate.

In the above scheme, the metal grating is located at the uppermost layer, the silicon substrate is the lowermost layer, and the "upper and lower" herein is merely a description of the positional relationship between the respective components, and does not limit the state of the overall structure.

The working principle and the effect of the scheme are as follows: according to the narrow-band near-infrared thermionic photodetector based on the embedded grating structure, the metal material is used as the light absorption layer, the metal grating is embedded into the silicon substrate, so that the light absorption efficiency and the thermionic generation rate of gold are further improved, the thermalization loss of thermionic is reduced, the Schottky interface on the side surface of the grating is increased, and the collection efficiency of thermionic transferred into silicon is improved. The response wavelength of the detector can be adjusted by changing the period of the metal grating, so that narrow-band photoelectric detection is realized.

Furthermore, the metal grating material is one or more of metal or metal alloy, metal nitride and metal oxide.

The preferred metal material may be one of gold, silver, copper and aluminum, and the metal grating thickness is 200 ~ 500 nm.

Further, the embedding depth of the metal grating embedded into the silicon substrate is 0 ~ 600 nm.

Further, the thickness of the titanium thin film layer positioned on the silicon substrate is 1 ~ 5 nm.

Further, the bottom conductive electrode on the back surface of the silicon substrate can be one of indium and aluminum.

Drawings

FIG. 1 is a front view of a narrow band near infrared thermionic photodetector structure based on an embedded grating structure;

FIG. 2 is a graph comparing the absorption rate of a transverse magnetic plane wave incident on a photodetector without an embedded grating structure;

FIG. 3 is a graph of optical responsivity contrast at different periods with a photodetector that does not incorporate an embedded grating structure;

FIG. 4 is a flow chart of an experimental preparation of an embedded metal grating structure;

in the figure: 1-silicon substrate, 2-titanium film layer, 3-metal grating, 4-top conductive electrode, 5-bottom conductive electrode.

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the drawings of the embodiments of the present invention. It is to be understood that the embodiments described are only a few embodiments of the present invention, and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the described embodiments of the invention, are within the scope of the invention.

The technical scheme of the invention is further explained in detail by combining the drawings in the specification.