Spectrum detection device based on regulation and control of thickness of absorption layer of semiconductor material

文档序号:1848495 发布日期:2021-11-16 浏览:26次 中文

阅读说明:本技术 一种基于调控半导体材料吸收层厚度的光谱探测器件 (Spectrum detection device based on regulation and control of thickness of absorption layer of semiconductor material ) 是由 徐杨 陈丽 李泠霏 刘威 田丰 吴少雄 吕建杭 李涵茜 俞滨 于 2021-07-16 设计创作,主要内容包括:本发明公开了一种基于调控半导体材料吸收层厚度的光谱探测器件。该器件包括绝缘层、半导体材料吸收层、正电极、负电极及二维材料薄膜,半导体材料吸收层呈阶梯阵列结构。有光线入射时,由于二维材料的高透光率,光线进入半导体材料并被吸收,不同波长入射光在半导体材料吸收层中的吸收深度不同,因此,对于特定厚度的半导体材料吸收层,对于不同波长的入射光其吸收量不同,对应可贡献光电流不同。各阶梯单元对应的两端电极之间均施加相同恒定电压,分别读取各阶梯单元黑暗和光照条件下产生的电流信号,取二者之差作为最终光电流信号,与预先标定构建的器件不同阶梯单元下响应度-波长谱建立线性方程组求解最优解,即可获取入射光谱信息。(The invention discloses a spectrum detection device based on regulation and control of the thickness of an absorption layer of a semiconductor material. The device comprises an insulating layer, a semiconductor material absorbing layer, a positive electrode, a negative electrode and a two-dimensional material film, wherein the semiconductor material absorbing layer is in a ladder array structure. When light enters, the light enters the semiconductor material and is absorbed due to the high light transmittance of the two-dimensional material, and the absorption depths of the incident light with different wavelengths in the semiconductor material absorption layer are different, so that the absorption amount of the incident light with different wavelengths is different for the semiconductor material absorption layer with a specific thickness, and the corresponding light currents can be contributed to be different. The same constant voltage is applied between the electrodes at the two ends corresponding to each step unit, the current signals generated under the dark and light conditions of each step unit are respectively read, the difference between the two current signals is taken as the final photocurrent signal, and a linear equation set is established with the responsivity-wavelength spectrum under different step units of the device which is calibrated in advance to solve the optimal solution, so that the incident spectrum information can be obtained.)

1. The spectrum detection device based on the regulation and control of the thickness of the semiconductor material absorption layer is characterized by comprising an insulating layer, the semiconductor material absorption layer with a ladder array structure is embedded on the upper surface of the insulating layer, negative electrodes are arranged on the upper surface of the insulating layer which is used as isolation between adjacent ladder units, a positive electrode is arranged on the upper surface of each ladder unit and covered with a two-dimensional material film which is not in contact with the positive electrode, and the two-dimensional material film covers the adjacent negative electrodes at the same time.

2. The device for spectrum detection based on regulation and control of thickness of semiconductor material absorption layer according to claim 1, characterized in that the semiconductor material absorption layer is a bulk material with high light absorption rate in a wider spectral range, comprising silicon or germanium.

3. The device for spectrum detection based on adjustment and control of thickness of absorption layer of semiconductor material according to claim 1, wherein the insulating layer is a comb-tooth structure as a whole, and the height of each comb tooth is different.

4. The device for spectrum detection based on thickness regulation of semiconductor material absorption layer according to claim 1, wherein the height and variation amplitude of each step unit of the step array are determined according to the wavelength range and accuracy of the device detection target.

5. The device for spectrum detection based on regulation and control of thickness of absorption layer of semiconductor material of claim 1, wherein each step unit is a two-step structure, the upper step is covered with a two-dimensional material film in whole or in part, and the lower step is provided with a positive electrode.

6. The device for spectrum detection based on regulation and control of thickness of absorption layer of semiconductor material according to claim 1, wherein the two-dimensional material thin film is a high light transmittance two-dimensional material comprising single-layer or few-layer graphene, single-layer or few-layer transition metal sulfide or single-layer or few-layer transition metal selenide.

7. The device for spectrum detection based on adjustment and control of thickness of absorbing layer of semiconductor material of claim 1, wherein light is incident from above the device to ensure uniform irradiation to each step unit in the step array, the same constant voltage is applied between the electrodes at two ends corresponding to each step unit, and the current signals generated under dark and light conditions of each step unit are read respectively, and the difference is taken as the final photocurrent signal.

8. The spectrum detection device based on the regulation and control of the thickness of the absorption layer of the semiconductor material according to claim 7, wherein the amplitude of the constant voltage applied between the electrodes at the two ends corresponding to each step unit is required to ensure that the depletion region is large enough to ensure high separation and transport efficiency of the photon-generated carriers.

9. The device for spectrum detection based on thickness regulation of the semiconductor material absorption layer as claimed in claim 1, wherein the absorption depth of the incident light with different wavelengths in the semiconductor material absorption layer is different, so that for the semiconductor material absorption layer with a specific thickness, the absorption amount of the incident light with different wavelengths is different, and the number of photo-generated carriers which can contribute to photocurrent is different; measuring the photocurrent of each step unit in advance through monochromatic light with known wavelength and light power to construct a responsivity-wavelength spectrum; and then, for the incident light with unknown wavelength, measuring the photocurrent generated by each step unit, and solving the optimal solution of the linear equation set by combining the responsivity-wavelength spectrum to obtain the wavelength of the incident light.

Technical Field

The invention belongs to the technical field of spectrum detection, and relates to a spectrum detection device based on regulation and control of the thickness of an absorption layer of a semiconductor material.

Background

The spectrum detection technology has wide application in the fields of food detection, substance identification, medical research, biochemical detection, environmental security and the like, but the existing mainstream mature spectrum detection equipment is huge in size and lacks portability, and the requirement of on-site quick detection is difficult to meet. In recent years, many miniaturized portable micro-spectral detectors have been developed in the market, and the size of the detectors has been greatly reduced compared with the conventional spectral detectors, but the degree of on-chip integration is still difficult to achieve. At present, commercial micro spectrum detection equipment essentially still achieves the purpose through system integration of an independent light splitting optical component and a photoelectric detector, and the light splitting optical system and a photoelectric conversion system are mutually independent. Nowadays, electronic products face market demands of smaller size and higher integration level, systems are mutually independent, and the size of optical components is limited in micro-scale, so that the method brings convenience for introducing a spectrum detection technology into the electronic products and integrating related functions of a spectrum.

The research of some emerging spectrum detection devices based on photonic crystals and super-surfaces at present realizes the function of obtaining wavelength information without the help of optical elements, but the mutual independence of the filtering array and the detection array is still not changed on the structure.

Therefore, the exploration of a new wavelength information acquisition method and the search of a novel spectral detection device integrating filtering and detection become a research direction with theoretical value and practical value in the current spectral detection technical field, are great trends in the development of the times, and have important significance and promotion effect on the development of the technical fields of multi-color detection, spectral detection and multi-spectral imaging.

Disclosure of Invention

The invention aims to overcome the defects in the prior art and provides a spectrum detection device based on the regulation and control of the thickness of an absorption layer of a semiconductor material.

The purpose of the invention is realized by the following technical scheme: the spectrum detection device comprises an insulating layer, wherein a semiconductor material absorption layer with a ladder array structure is embedded on the upper surface of the insulating layer, negative electrodes are arranged on the upper surface of the insulating layer which is used as isolation between adjacent ladder units, a positive electrode is arranged on the upper surface of each ladder unit, a two-dimensional material film which is not in contact with the positive electrode covers the upper surface of each ladder unit, and the two-dimensional material film covers the adjacent negative electrodes at the same time.

Further, the semiconductor material absorption layer is a bulk material with high light absorption in a wider spectral range, including silicon or germanium.

Furthermore, the whole insulating layer is of a comb-tooth-shaped structure, and the heights of the comb teeth are different.

Furthermore, the height and the variation amplitude of each step unit of the step array are determined according to the wavelength range and the precision of the detection target of the device.

Furthermore, each ladder unit is of a two-stage ladder structure, the upper ladder is completely or partially covered with a two-dimensional material film, and the lower ladder is provided with a positive electrode.

Further, the two-dimensional material film is a high-light-transmittance two-dimensional material and comprises a single layer or few layers of graphene, a single layer or few layers of transition metal sulfide or a single layer or few layers of transition metal selenide.

Further, light is incident from the upper part of the device (namely one side of the ladder array), uniform irradiation to each ladder unit in the ladder array is ensured, the same constant voltage is applied between electrodes at two ends corresponding to each ladder unit, current signals generated under dark and light conditions of each ladder unit are respectively read, and the difference between the two current signals is taken as a final photocurrent signal.

Further, the amplitude of the constant voltage applied between the electrodes at the two ends corresponding to each step unit needs to ensure that the depletion region is large enough to ensure high separation and transport efficiency of the photon-generated carriers.

Furthermore, the absorption depths of the incident light with different wavelengths in the semiconductor material absorption layer are different, so that for the semiconductor material absorption layer with a specific thickness, the absorption amounts of the incident light with different wavelengths are different, and the number of photon-generated carriers which can contribute to photocurrent is different correspondingly; measuring the photocurrent of each step unit in advance through monochromatic light with known wavelength and light power to construct a responsivity-wavelength spectrum; and then, for the incident light with unknown wavelength, measuring the photocurrent generated by each step unit, and solving the optimal solution of the linear equation set by combining the responsivity-wavelength spectrum to obtain the wavelength of the incident light.

The working principle of the spectrum detector provided by the invention is as follows:

(1) since the absorption depth of the incident light in the semiconductor material absorption layer is different for different wavelengths, the absorption depth of the incident light in the semiconductor material absorption layer is deeper as the wavelength increases. The thickness of each step unit in the step array is different, and the screening effect on the absorption amount of incident light is achieved.

(2) Applying the same constant voltage V across each ladder cell of the devicebiasSo that the device is in operation. Due to depletion region depth following VbiasIs widened, the photogenerated electron-hole pairs are separated in the depletion region, and thus V needs to be ensuredbiasIs large enough to ensure high photon-generated carrier separation and transport efficiency.

(3) For a staircase array comprising N steps, the photocurrent I measured by a single staircase cellkIs incident lightSpectrum P (lambda) and responsivity-wavelength spectrum R (lambda) in the wavelength range [ lambda ]12]The integral over (A) is shown in equation (1),

therefore, the device is calibrated in advance before being applied to spectrum detection, and the responsivity-wavelength spectrum R (lambda) is constructed. Monochromatic incident light with known wavelength and known optical power is uniformly irradiated on the surface of the ladder array, the photocurrent of each ladder unit is measured, the responsivity is calculated, and a responsivity-wavelength spectrum R (lambda) is constructed.

(4) When unknown incident light is incident, the incident light is uniformly irradiated to the whole ladder array, and the photocurrent I of each ladder unit is measured1,I2,…INThe method can establish a linear equation set comprising N equations according to the formula (1) and the pre-calibrated responsivity-wavelength spectrum R (lambda), and can judge the wavelength information of the incident light by solving the optimal solution of the linear equation set, thereby realizing the spectrum detection.

The invention has the following beneficial effects:

1. the device has simple structure, simple and understandable working principle and compatible preparation process and CMOS process.

2. The invention realizes the integration of light filtering and detection in a single device structure, can realize the direct identification of colors, and does not need to use a light splitting optical component.

3. The size of the device can be further reduced under the processing technology with higher precision, the occupation of physical space can be extremely small, and the device is easy to integrate in a miniature image sensor.

4. The device has various material choices, can determine the detectable spectrum range according to the absorption characteristics of the material, and has application flexibility.

Drawings

Fig. 1 is a schematic structural diagram of a spectrum detection device based on adjustment and control of thickness of an absorption layer of a semiconductor material, provided in an embodiment of the present invention, wherein an insulating layer 1, a semiconductor material absorption layer 2, a negative electrode 3, a positive electrode 4, and a two-dimensional material film 5 are provided;

FIG. 2 is a schematic diagram of the principle of spectrum detection of a device according to an embodiment of the present invention;

FIG. 3 is a schematic diagram of responsivity-wavelength spectrum R (λ) of a device obtained by simulation in the embodiment of the invention.

Detailed Description

The technical solutions in the embodiments of the present invention will be fully described below with reference to the accompanying drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the 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 embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

As shown in fig. 1, the spectrum detecting device based on the adjustment and control of the thickness of the absorption layer of the semiconductor material provided by the embodiment of the invention includes an insulating layer 1, a semiconductor material absorption layer 2 with a ladder array structure is embedded on the upper surface of the insulating layer 1, a negative electrode 3 is arranged on the upper surface of the insulating layer 1 which is used as an isolation between adjacent ladder units, a positive electrode 4 is arranged on the upper surface of each ladder unit and covered with a two-dimensional material film 5 which is not in contact with the positive electrode 4, and the two-dimensional material film 5 simultaneously covers the adjacent negative electrodes 3. In the embodiment, the insulating layer 1 is made of silicon dioxide, the semiconductor material absorbing layer 2 is made of silicon material, and the two-dimensional material film 5 is made of single-layer graphene.

The method for preparing the spectrum detection device based on the regulation and control of the thickness of the absorption layer of the semiconductor material comprises the following steps:

(1) an SOI substrate is taken, the top silicon is n-type high-resistance silicon, the resistivity is more than 10k omega cm, and the thickness is 2 mu m.

(2) And (2) manufacturing a rectangular array mask on the surface of the top silicon by using a photoetching technology, manufacturing a silicon column array by using a deep silicon etching technology, and growing oxide insulating layer silicon dioxide by using a PECVD method to isolate adjacent silicon column units.

(3) The silicon column arrays are processed by utilizing the gray scale photoetching technology and are subjected to dry etching, so that the silicon column arrays are arranged in a ladder shape, and the thicknesses of the ladder units are respectively 0.5 mu m, 0.7 mu m, 1.0 mu m, 1.3 mu m, 1.6 mu m and 1.9 mu m.

(4) Positive electrode patterns are made on the silicon stepped surface by using a photoetching technology, and in each stepped unit, the positive electrode is positioned on the silicon surface. The positive electrode region is heavily doped using ion implantation techniques.

(5) And (3) manufacturing negative electrode patterns on the silicon dioxide surface for isolating adjacent silicon column units by using a photoetching technology, wherein in each step unit, the positive electrode is positioned on the silicon surface, and the negative electrode is positioned on the silicon dioxide surface. And growing 5nm chromium and 40nm gold layers as electrodes by utilizing a magnetron sputtering technology.

(6) Covering a single-layer graphene film on the partial region surface of the silicon step and the corresponding negative electrode; graphene transfer using a wet process: uniformly spin-coating a layer of polymethyl methacrylate (PMMA) film on the surface of the single-layer graphene, then putting the single-layer graphene into an acidic etching solution, soaking for about 6 hours, and corroding to remove the copper foil, so that the single-layer graphene film supported by the PMMA is left; washing a graphene film supported by PMMA (polymethyl methacrylate) with deionized water, and transferring the washed graphene film to the upper surfaces of a silicon dioxide insulating layer, a source electrode and a drain electrode; finally, soaking the sample in acetone and isopropanol to remove PMMA; wherein the acid etching solution is prepared from CuSO4HCl and water, CuSO4:HCl:H2O=10g:45ml:50ml。

(7) And photoetching the device, and covering a defined area of the needed single-layer graphene pattern by using photoresist. Then, the power and the etching time are respectively 75W and 3min by using an Oxygen plasma reactive ion etching technology (Oxygen plasma ICP-RIE). And (3) etching the redundant graphene outside the photoresist to ensure that the graphene film of each step unit is not contacted with the positive electrode and the size of the graphene area on the surface is consistent. And after the etching is finished, cleaning with acetone and isopropanol to remove the residual photoresist.

(8) And carrying out RTP annealing treatment on the device, wherein the annealing temperature is 400 ℃, and the annealing time is 5 min.

The spectrum detection principle of the spectrum detection device is schematically shown in fig. 2. Since the absorption depth of the incident light in the semiconductor material absorption layer is different for different wavelengths, the absorption depth of the incident light in the semiconductor material absorption layer is deeper as the wavelength increases. The thickness of each step unit in the step array is different, and the screening effect on the absorption amount of incident light is achieved.

2V voltage is applied to each step unit of the spectrum detection device based on the regulation and control of the thickness of the absorption layer of the semiconductor material, and monochromatic light sources with different wavelengths in the wavelength range of the visible light band are selected for pre-calibration. Under dark condition, measuring dark current of each step unit, making monochromatic incident light uniformly irradiate on the surface of the device step array, measuring current of each step unit, and obtaining current difference value under light-dark condition of N step units as photocurrent I1,I2,…INCalculating the responsivity as R1,R2,…RN. And measuring and calculating the responsivity of each step unit of the device under each wavelength of monochromatic light, and constructing a responsivity-wavelength spectrum R (lambda). The responsivity-wavelength spectrum of the step unit with different thicknesses obtained through theoretical calculation and simulation is shown in fig. 3.

Monochromatic light or polychromatic light with the wavelength within a calibration wavelength range is selected as unknown incident light to be uniformly irradiated on the surface of the device stepped array. And measuring the light current value of each step unit, constructing a linear equation set by combining the responsivity-wavelength spectrum R (lambda), solving the optimal solution of the linear equation set, and ensuring that the wavelength solving result is consistent with the actual incident light, namely the device has the spectrum detection capability.

The invention realizes the purpose of spectrum detection by utilizing the difference brought by different incident light wavelengths and different absorption layer thicknesses based on the absorption characteristics of semiconductor materials. The invention is suitable for the detection wave band to be adjusted by selecting different semiconductor materials, the spectral detection precision can be adjusted according to the preparation process limit and the thickness interval of the absorption layer required to be adjusted in the practical application scene, and the invention can be applied to the fields of multicolor detection, spectral detection and further multispectral imaging.

The foregoing is only a preferred embodiment of the present invention, and although the present invention has been disclosed in the preferred embodiments, it is not intended to limit the present invention. Those skilled in the art can make numerous possible variations and modifications to the present teachings, or modify equivalent embodiments to equivalent variations, without departing from the scope of the present teachings, using the methods and techniques disclosed above. Therefore, any simple modification, equivalent change and modification made to the above embodiments according to the technical essence of the present invention are still within the scope of the protection of the technical solution of the present invention, unless the contents of the technical solution of the present invention are departed.

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