CN116322246A - A transistor-type photodetector based on bismuth sulfide thin film and its preparation method - Google Patents

Abstract

The application relates to a transistor type photoelectric detector based on bismuth sulfide thin films and a preparation method thereof. The method comprises the following steps: depositing a dielectric layer on a substrate; bi is mixed with ₂ S ₃ Spin-coating the precursor solution onto the dielectric layer, and annealing at 100-300 ℃ to form Bi ₂ S ₃ A film; at the Bi of ₂ S ₃ Evaporating source and drain electrodes on the film. The photoelectric detector combines the characteristics of grid voltage regulation and control, high gain and easy integration of the field effect transistor and Bi ₂ S ₃ The method has the advantages of wide absorption range, simple operation, low cost, easily obtained materials, easily regulated components and the like in the preparation process, low requirements on environment and equipment, high light sensitivity, low noise current and high specific detection rate, wide detectable light wavelength range, excellent detection performance and great application potential in the field of photoelectric detection.

Description

A transistor-type photodetector based on bismuth sulfide thin film and its preparation method

technical field

The present application relates to the technical field of optoelectronic devices, in particular to a bismuth sulfide thin film-based transistor-type photodetector and a preparation method thereof.

Background technique

Sulfide is characterized by its excellent light absorption coefficient, adjustable band gap and absorption range, strong stability (including air stability, temperature stability and humidity stability, etc.), lower cost and more preparation routes , has received extensive attention from academia and industry in the fields of photovoltaics, photocatalysis, and photodetection. Among them, the common ones, such as binary chalcogenides such as CdTe, Sb ₂ S ₃ , Sb ₂ Se ₃ and ternary sulfide materials such as CuSbS ₂ , AgSbS ₂ , AgBiS ₂ , NaBiS _{2 ,} etc., are all used in the photoelectric field, especially in photocatalysis and Good progress has been made in the research and application of photovoltaics.

Among them, the bismuth-based chalcogenide Bi ₂ S ₃ has considerable application prospects due to its larger absorption range and higher absorption coefficient. At present, the excellent photoelectric properties of Bi ₂ S ₃ are mainly used in the field of photocatalysis, but due to the many defects in it seriously affecting the transport of photogenerated carriers, there are few reports in the field of photodetectors. At the same time, photoconductive and photodiode detectors are severely limited in their application in highly sensitive photodetectors due to their relatively low optical gain and complex interfacial recombination. In contrast, phototransistor detectors have the advantages of being adjustable by gate voltage, high gain, wide operating voltage range, and easy compatibility with CMOS integrated circuits.

At present, Bi ₂ S ₃ is mostly prepared by chemical bath deposition (CBD), thermal evaporation, and hydrothermal method to prepare nanostructures such as nanowires or nanotubes. These methods can prepare Bi ₂ S ₃ with relatively high crystal quality. However, there are problems such as high cost, complex and expensive equipment, long preparation cycle, difficult to accurately control the reaction rate, difficult to accurately control the material composition and doping concentration, and the residual reactants on the inner wall surface of the experimental container, resulting in cumbersome subsequent cleaning steps.

Therefore, how to apply it to the field of photodetectors through a low-cost and simple method under the premise of ensuring the quality of Bi ₂ S ₃ film formation will have great application prospects.

Contents of the invention

The embodiment of the present application provides a transistor-type photodetector based on bismuth sulfide thin film and its preparation method to solve the problems of high preparation cost, difficult control of reaction rate, difficult control of material components, _and experimental procedures of _Bi2S3 thin film in the related art. cumbersome and difficult to apply to problems in photodetectors.

The technical scheme that this application provides is as follows:

In a first aspect, the present application provides a method for preparing a transistor-type photodetector based on a bismuth sulfide thin film, comprising the following steps:

depositing a dielectric layer on the substrate;

spin-coating the Bi ₂ S ₃ precursor solution onto the dielectric layer, and annealing at 100-300° C. to form a Bi ₂ S ₃ film;

Evaporate source and drain electrodes on the Bi ₂ S ₃ film.

In some embodiments, the molar ratio of bismuth and sulfur in the Bi ₂ S ₃ precursor solution is 1:(1.5˜2.5).

In some embodiments, the Bi ₂ S ₃ precursor solution further includes Na ⁺ or Ag ⁺ .

In some embodiments, the concentration of Na ⁺ or Ag ⁺ in the Bi ₂ S ₃ precursor solution is 1%-10% of the total concentration of bismuth and sulfur.

In some embodiments, "annealing at 100-300°C" specifically includes:

Under an inert atmosphere, perform pre-annealing treatment, the pre-annealing temperature is 60°C-150°C, and the pre-annealing time is 5-50min;

Then perform post-annealing treatment in the air, the post-annealing temperature is 200°C-350°C, and the post-annealing time is 5-30min.

In some embodiments, the dielectric layer is at least one of SiO ₂ , Ta ₂ O ₅ , and Al ₂ O ₃ ;

And/or, the substrate uses Si or ITO.

In some embodiments, the thickness of the dielectric layer is 50-300 nm;

And/or, the thickness of the Bi ₂ S ₃ film is 5-60 nm;

And/or, the thickness of the source-drain electrodes is 50-200 nm.

In some embodiments, "evaporating source and drain electrodes on _{the Bi2S3} film" specifically includes:

Evaporate metal on the Bi ₂ S ₃ film to form source and drain electrodes;

or,

On the Bi ₂ S ₃ film, evaporate C60 or MoO _x first, and then evaporate metal to form source and drain electrodes.

In some embodiments, the metal includes Ag, Au, Cu or Al.

In the second aspect, the present application also provides a transistor-type photodetector based on a bismuth sulfide thin film, which is prepared by any of the methods described above.

The beneficial effects brought by the technical solution provided by the application include:

The present invention directly deposits the _Bi2S3 thin film on the dielectric layer, and this method takes the _Bi2S3 thin film into account at the same time as the channel layer and the light absorbing layer, and has high mobility, _better carrier transport _performance , and high light absorption intensity And wide light absorption range and other properties, so that the prepared photodetector has the advantages of being adjustable through the grid voltage, high gain under illumination and a wide range of detection wavelengths;

The present _invention obtains the _Bi2S3 thin film by spin-coating the precursor solution method, which avoids the problem that the reaction rate and material components are difficult to control in methods such as hydrothermal method, evaporation method and chemical bath deposition, the experimental process is simple, and the cost of raw materials used is low , the equipment requirements are simple, and the quality of the prepared film is good.

Description of drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings that need to be used in the description of the embodiments will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present application. For those skilled in the art, other drawings can also be obtained based on these drawings without creative effort.

FIG. 1 is a schematic diagram of a transistor-type photodetector based on a bismuth sulfide thin film provided in Example 1 of the present application;

Fig. 2 is the transmission and reflection spectrum of the Bi ₂ S ₃ thin film that the application embodiment 1-3 and comparative example 1-2 prepare;

Fig. 3 is the transfer curve of the photodetector provided by the embodiment of the present application at different operating temperatures, wherein Fig. 3 (a) is the transfer curve of the photodetector prepared in Comparative Example 1 at different operating temperatures, and Fig. 3 (b ) is the transfer curve of the photodetector prepared in Example 1 at different operating temperatures, and Fig. 3 (c) is the transfer curve of the photodetector prepared in Example 2 at different operating temperatures, and Fig. 3 (d) is the transfer curve of the embodiment 3 transfer curves of the prepared photodetector at different operating temperatures, and Fig. 3 (e) is the transfer curve of the photodetector prepared in Comparative Example 2 at different operating temperatures;

Fig. 4 is the transfer curve of the photodetector provided by the embodiment of the present application at different test temperatures, wherein Fig. 4 (a) is the transfer curve of the photodetector prepared in Example 1 at different operating temperatures, and Fig. 4 ( b) is the transfer curve of the photodetector prepared in Example 4 at different operating temperatures, and Fig. 4 (c) is the transfer curve of the photodetector prepared in Example 5 at different operating temperatures;

Fig. 5 is the transfer curve of the photodetector provided by the embodiment of the present application under dark state and light, wherein, Fig. 5 (a) is the transfer curve of the photodetector prepared in Example 1 under dark state and light, Fig. 5 (b) is the transfer curve of the photodetector prepared in embodiment 4 under dark state and illumination, and Fig. 5 (c) is the transfer curve of the photodetector prepared in embodiment 5 in dark state and illumination;

Fig. 6 is the transfer curve of the photodetector provided by the embodiment of the present application, wherein, Fig. 6 (a) is the transfer curve of the photodetector prepared in embodiment 1, embodiment 6 and comparative example 4 in the dark state, Fig. 6 (b) is the transfer curve of the photodetector prepared in embodiment 1, embodiment 6 under dark state and illumination;

Fig. 7 is the photoconductivity figure of the thin film that the application embodiment 1 and comparative example 3 provide;

Figure 8 is the transfer curve of the photodetector provided in Example 1 of the present application under the irradiation of LED lamps with different optical powers when the source-drain voltage is 40V, wherein Figure 8(a) is the transfer curve of 400nm LED irradiation, and Figure 8( b) is the transfer curve of 530nm LED irradiation, and Fig. 8(c) is the transfer curve of 730nm LED irradiation;

Fig. 9 is a performance characterization diagram of the photodetector provided in Example 1 of the present application, wherein Fig. 9(a) is a photosensitivity diagram, Fig. 9(b) is a noise power spectral density diagram, and Fig. 9(c) is a responsivity And the specific detection rate map;

FIG. 10 is a schematic diagram of a transistor-type photodetector based on a bismuth sulfide thin film provided in Example 7 of the present application;

Figure 11 is the transfer curve of the photodetector provided by Embodiment 7 of the present application;

FIG. 12 is a transfer curve of the photodetector provided in Example 1 of the present application after being baked in an environment of 100° C.

In the figure: 1. substrate; 2. dielectric layer; 3. Bi ₂ S ₃ thin film; 4. source and drain electrodes.

Detailed ways

In order to make the purpose, 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 in conjunction with the embodiments of the present application and the accompanying drawings. Obviously, the described embodiments are Some embodiments of the present application, but not all embodiments. Based on the embodiments in the present application, all other embodiments obtained by persons of ordinary skill in the art without making creative efforts belong to the protection scope of the present application.

Referring to FIG. 1, in the first aspect, the embodiment of the present application provides a method for preparing a transistor-type photodetector based on a bismuth sulfide thin film, including the following steps:

S1: depositing a dielectric layer 2 on the substrate 1;

S2: Spin-coat the Bi ₂ S ₃ precursor solution onto the dielectric layer 2, and anneal at 100-300° C. to form a Bi ₂ S ₃ thin film 3;

S3: Evaporating source and drain electrodes 4 on the Bi ₂ S ₃ thin film 3 .

The present invention directly deposits the _Bi2S3 thin film on the dielectric layer, and this method takes the _Bi2S3 thin film into account at the same time as the channel layer and the light absorbing layer, and has high mobility, _better carrier transport _performance , and high light absorption intensity And wide light absorption range and other properties, so that the prepared photodetector has the advantages of being adjustable through the grid voltage, high gain under illumination and a wide range of detection wavelengths;

The present _invention obtains the _Bi2S3 thin film by spin-coating the precursor solution method, which avoids the problem that the reaction rate and material components are difficult to control in methods such as hydrothermal method, evaporation method and chemical bath deposition, the experimental process is simple, and the cost of raw materials used is low , the equipment requirements are simple, and the quality of the prepared film is good.

In a preferred embodiment, the preparation method of Bi ₂ S ₃ precursor solution includes:

Dissolve bismuth nitrate pentahydrate powder in ethylene glycol monomethyl ether, the concentration of Bi in the solution is 0.1-0.6mol/L, stir on the stirrer for 2-5min until completely dissolved, then add thiourea, so that the S in the solution The concentration is 0.15-0.9 mol/L, and the stirring is continued for 2-5 minutes to obtain a light yellow and clear Bi ₂ S ₃ precursor solution.

Further, preferably, the concentration of Bi in the solution is 0.4 mol/L, and the concentration of S is 0.6 mol/L.

In some embodiments, the molar ratio of bismuth and sulfur in the Bi ₂ S ₃ precursor solution is 1:(1.5˜2.5).

By adjusting the molar ratio of bismuth and sulfur in the Bi ₂ S ₃ precursor solution to 1: (1.5-2.5), the crystal quality, optical properties and carrier transport properties of the Bi ₂ S ₃ film were effectively improved, thereby improving its Photoelectric properties applied to photodetectors.

In a preferred embodiment, the molar ratio of bismuth and sulfur in the Bi ₂ S ₃ precursor solution is 1:1.5.

In some embodiments, the Bi ₂ S ₃ precursor solution further includes Na ⁺ or Ag ⁺ .

By doping a small amount of Ag ⁺ or Na ⁺ in the Bi ₂ S ₃ precursor solution, it is attempted to improve the carrier transport performance of the semiconductor material by changing the crystal quality of the film through ion doping, and then optimize the doped Bi ₂ S ₃ transistor performance.

In some embodiments, the concentration of Na ⁺ or Ag ⁺ in the Bi ₂ S ₃ precursor solution is 1%-10% of the total concentration of bismuth and sulfur.

In a preferred embodiment, the concentration of Na ⁺ or Ag ⁺ is 5% of the total concentration of bismuth and sulfur.

In some embodiments, "annealing at 100-300°C" specifically includes:

S201: Under an inert atmosphere, perform pre-annealing treatment, the pre-annealing temperature is 60°C-150°C, and the pre-annealing time is 5-50min;

S202: Then perform a post-annealing treatment in air, the post-annealing temperature is 200°C-350°C, and the post-annealing time is 5-30min.

In a preferred embodiment, the pre-annealing temperature is 95-105°C; the post-annealing temperature is 275-285°C.

In some embodiments, the dielectric layer 2 is at least one of SiO ₂ , Ta ₂ O ₅ , and Al ₂ O ₃ ;

And/or, the substrate 1 is made of Si or ITO.

In a preferred embodiment, the substrate 1 adopts ITO, and the dielectric layer 2 adopts a double dielectric layer comprising SiO ₂ and Ta ₂ O ₅ , which has a higher sensitivity.

In some embodiments, the thickness of the dielectric layer 2 is 50-300 nm;

And/or, the thickness of the Bi ₂ S ₃ thin film 3 is 5-60 nm;

And/or, the thickness of the source-drain electrodes 4 is 50-200 nm.

In a preferred embodiment, the thickness of the Bi ₂ S ₃ thin film 3 is 25 nm.

In some embodiments, "evaporating source and drain electrodes 4 on the Bi ₂ S ₃ thin film 3" specifically includes:

Evaporate metal on _{the Bi2S3} thin film 3 to form source and drain electrodes 4;

or,

C60 or MoO _x is vapor-deposited on the Bi ₂ S ₃ film 3 first, and then metal is vapor-deposited to form the source-drain electrodes 4 .

Specifically, the source-drain electrodes 4 provided in the present application have two structures, one is a pure metal single-layer structure, and the other is a double-layer composite structure of C60 or MoO _x and metal.

Further, the second structure is preferred, because the C60 or MoO _x disposed between the Bi ₂ S ₃ thin film 3 and the metal can improve the charge extraction capability.

In a preferred embodiment, the thickness of C60 or MoO _x is 10-35 nm.

Further, C60 or MoO _x can be deposited by vacuum thermal evaporation.

In some embodiments, the metal includes Ag, Cu, Au, or Al.

In a preferred embodiment, the metal can be deposited by vacuum thermal evaporation.

In the second aspect, the embodiment of the present application also provides a transistor-type photodetector based on bismuth sulfide thin film, which is prepared by any of the methods described above.

The invention finally prepares a phototransistor type detector with excellent performance, which has a light sensitivity exceeding 10 ⁴ , a noise current lower than 1pA/Hz ^1/2 and a specific detection rate exceeding 10 ¹⁴ Jones. At the same time, the prepared detector device has good environmental stability and has a certain tolerance to temperature and air, which provides more favorable conditions for subsequent applications.

The present application is further described through specific examples below.

Example 1

Referring to FIG. 1 , a transistor-type photodetector based on a bismuth sulfide thin film includes a substrate 1 , a dielectric layer 2 , a Bi ₂ S ₃ thin film 3 (thickness 25 nm), and source-drain electrodes 4 that are sequentially stacked.

A method for preparing a transistor-type photodetector based on a bismuth sulfide thin film, comprising the steps of:

S1: Deposit a SiO ₂ dielectric layer on the surface of the Si substrate;

S2: Dissolve bismuth nitrate pentahydrate powder in ethylene glycol monomethyl ether, stir on a stirrer for 2-5 minutes until completely dissolved, then add thiourea, and continue stirring for 2-5 minutes to obtain a pale yellow and clear Bi ₂ S ₃ precursor solution, wherein the molar ratio of Bi and S in the Bi ₂ S ₃ precursor solution is 1:1.5;

S3: Spin-coat the Bi ₂ S ₃ precursor solution onto the surface of the SiO ₂ dielectric layer, anneal at 100°C for 10 min in N ₂ atmosphere, and then anneal at 280°C for 5 min in air to form a Bi ₂ S ₃ film;

S4: C60 and Al are sequentially vacuum thermally evaporated on the surface of the Bi ₂ S ₃ film to form source and drain electrodes.

Example 2

Including most of the operating steps of Example 1, the difference is only in:

In step S2, the molar ratio of Bi and S is 1:2.

Example 3

Including most of the operating steps of Example 1, the difference is only in:

In step S2, the molar ratio of Bi and S is 1:2.5.

Example 4

Including most of the operating steps of Example 1, the difference is only in:

In step S2, the Bi ₂ S ₃ precursor solution is also doped with Ag ⁺ , and the concentration of Ag ⁺ is 5% of the concentration of the Bi ₂ S ₃ solution.

Example 5

Including most of the operating steps of Example 1, the difference is only in:

In step S2, the Bi ₂ S ₃ precursor solution is also doped with Na ⁺ , and the concentration of Na ⁺ is 5% of the concentration of the Bi ₂ S ₃ solution.

Example 6

Including most of the operating steps of Example 1, the difference is only in:

The thickness of the Bi ₂ S ₃ film is 60 nm.

Example 7

Referring to FIG. 10 , a transistor-type photodetector based on a bismuth sulfide thin film includes a substrate 1 , a dielectric layer 2 , a Bi ₂ S ₃ thin film 3 (thickness 25 nm), and source and drain electrodes 4 that are sequentially stacked.

A method for preparing a transistor-type photodetector based on a bismuth sulfide thin film, comprising the steps of:

S1: Deposit Ta ₂ O ₅ on the surface of ITO transparent conductive glass by magnetron sputtering, and then deposit SiO ₂ on the surface of Ta ₂ O ₅ by solution spin coating to form a composite dielectric layer;

S2: Dissolve bismuth nitrate pentahydrate powder in ethylene glycol monomethyl ether, stir on a stirrer for 2-5 minutes until completely dissolved, then add thiourea, and continue stirring for 2-5 minutes to obtain a pale yellow and clear Bi ₂ S ₃ precursor solution, wherein the molar ratio of Bi and S in the Bi ₂ S ₃ precursor solution is 1:1.5;

S3: Spin-coat the Bi ₂ S ₃ precursor solution onto the surface of the composite dielectric layer, anneal at 100°C for 10 min in N ₂ atmosphere, and then anneal at 280°C for 5 min in air to form a Bi ₂ S ₃ film;

S4: C60 and Al are sequentially vacuum thermally evaporated on the surface of the Bi ₂ S ₃ film to form source and drain electrodes.

Comparative example 1

Including most of the operating steps of Example 1, the difference is only in:

In step S2, the molar ratio of Bi and S is 1:1.3.

Comparative example 2

Including most of the operating steps of Example 1, the difference is only in:

In step S2, the molar ratio of Bi and S is 1:3.

Comparative example 3

Including most of the operating steps of Example 1, the difference is only in:

In step S3, the pre-annealing operation remains unchanged, and the Bi ₂ S ₃ film is formed by annealing at 280° C. for 3 minutes in air.

Comparative example 4

Including most of the operating steps of Example 1, the difference is only in:

The thickness of the Bi ₂ S ₃ film is 160 nm.

Referring to shown in Fig. 2, Fig. 2 has shown embodiment 1-3 and comparative example 1-2 Bi ₂ S The transmission and reflection spectrum of the thin film of S _1-2 preparation, it can be seen that the molar ratio of Bi and S in the current flooding solution is less than 1 : 1.5, the transmittance of the obtained film is significantly improved under the light of less than 600nm, the reflectance is reduced, and no obvious absorption edge is formed, which indirectly shows that the Bi ₂ S ₃ on the film is not completely crystallized. Bi in the current flooding solution When the molar ratio of Bi and S is greater than 1:2.5, the obtained film has low reflectivity and large scattering loss, which also indirectly reflects that the surface of the film is not bright and dense enough, so it is necessary to increase the molar ratio of Bi and S in the precursor solution The ratio is controlled at 1:(1.5～2.5) so that the Bi ₂ S ₃ film has higher reflectivity and lower transmittance, and the film has the highest reflectivity when the molar ratio of Bi and S is 1:1.5 And the lowest transmittance, which also indirectly reflects that the film has lower scattering loss and better density when the molar ratio of Bi and S is 1:1.5.

Referring to shown in Fig. 3, Fig. 3 has shown the transfer curve of the photodetector prepared by embodiment 1-3 and comparative example 1-2 under different test temperatures, as can be seen, when the mol ratio of Bi and S is at 1:1.5 , it has more suitable threshold voltage, smaller sub-threshold swing, lower off-state current and higher on-state current, and its threshold voltage can be better controlled by temperature, and the maximum on-off ratio exceeds 10 ⁴ .

Referring to Figure 4, Figure 4 shows the transfer curves of the photodetectors prepared in Example 1 and Example 4-5 at 20°C and -20°C. On the basis of doping Ag ⁺ or Na ⁺ , the off-state current of the photodetector prepared by doping Ag ⁺ is 10pA～20pA, the threshold voltage is -15V～-10V, and the off-state current of Example 1 is 50pA～ 90pA, the threshold voltage is about -20V, it can be seen that compared with the embodiment 1, the embodiment 4-5 has a lower off-state current and a more suitable threshold voltage.

Referring to shown in Fig. 5, Fig. 5 has shown the transfer curve of the photodetector prepared in embodiment 1 and embodiment 4-5 under darkness and light, as can be seen, the photodetector prepared in embodiment 4-5 is working The optical gain in the voltage range is close to 10 ³ , and the optical gain in Example 1 is only about 10. It can be seen that the doping of Ag ⁺ or Na ⁺ can further improve the quality of the film, thereby increasing the optical gain of the device.

Referring to shown in Fig. 6, wherein, Fig. 6 (a) has shown the transfer curve of the photodetector prepared in the dark under 20 ℃ of embodiment 1, embodiment 6 and comparative example 4, it can be seen that the film has Good carrier transport performance, the current between the source and drain can be regulated by the gate voltage; and when the film is close to 60nm, the carrier transport performance is significantly reduced, even at a higher gate voltage Low source-drain current, which will severely limit its photosensitive performance; when the film thickness reaches 160nm, there is no normal transfer curve of the transistor at all, and the carrier channel cannot be formed in the film under the control of the gate voltage, which also indirectly shows that the film The number of defects in the medium increases and the recombination increases, so it is necessary to control the thickness of the Bi ₂ S ₃ film at 25-60nm;

Figure 6(b) shows the transfer curves of the photodetectors prepared in Example 1 and Example 6 at -20°C under dark and light conditions. It can be seen that the dark current of Example 1 is about 60pA, and the threshold voltage is - 30V, light-dark switch ratio exceeds 10; The dark current of embodiment 6 is 200pA, threshold voltage is less than-40V, and light-dark switch ratio is less than 5 explanation when Bi ₂ S ₃ film has lower dark current when 25nm, more suitable threshold voltage and greater light-to-dark switching ratio.

Referring to shown in Fig. 7, Fig. 7 (b) has shown the photoconductive property of the thin film prepared in comparative example 3, and Fig. 7 (a) has shown the photoconductive property of the thin film prepared in embodiment 1, as can be seen, comparative example 3 is carried out Short-term high-temperature annealing increases the dark current by more than 100 times, and the background carrier concentration of the film is too high, but the photocurrent does not change significantly. There are a large number of holes, so the annealing treatment method of the present application can further improve the film quality, reduce device noise, and improve photosensitive performance.

Referring to Figure 8, Figure 8 shows the transfer curves of the photodetectors prepared in Example 1 under different light intensities under the illumination of 400nm, 530nm and 730nm LEDs, wherein the source-drain voltage is 20V, it can be seen that the embodiment of the present application provides The photodetector has good photosensitive performance in the visible light range, and even under the weak light of 0.03μW/ ^cm2 , it has an optical gain of nearly 10 times, with high sensitivity and good weak light detection ability .

Referring to Fig. 9, Fig. 9 shows the photosensitivity, noise power spectrum, responsivity and specific detectivity diagram of the photodetector prepared in embodiment 1, it can be seen that the photodetector provided in embodiment 1 of the present application has a lower Noise current and good photoelectric detection ability, its light sensitivity exceeds 10 ⁴ , and its specific detection rate can exceed 10 ¹⁴ .

Referring to Figure 11, Figure 11 shows the transfer curve of the photodetector prepared in Example 7. It can be seen that Example 7 uses ITO as the substrate in combination with SiO ₂ and Ta ₂ O ₅ double dielectric layers, so that the device also performs Excellent transistor performance, its on-off ratio exceeds 10.

In addition, a stability test was carried out on the photodetector prepared in Example 1 of the present application, and it was found that the detector could work stably at 100°C for a period of time, and the performance opportunity remained unchanged, as shown in Figure 12, indicating that the device has a certain thermal stability. After placing the device in the air for a period of time, the device can still work normally after one month, and the performance degradation is small, indicating that the device has good long-term stability.

The above descriptions are only specific implementation manners of the present application, so that those skilled in the art can understand or implement the present application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the application. Therefore, the present application will not be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features claimed herein.

Claims (10)

1. The preparation method of the transistor type photoelectric detector based on the bismuth sulfide film is characterized by comprising the following steps of:

depositing a dielectric layer (2) on a substrate (1);

bi is mixed with ₂ S ₃ Spin-coating the precursor solution onto the dielectric layer (2), and annealing at 100-300 ℃ to form Bi ₂ S ₃ A film (3);

at the Bi of ₂ S ₃ And evaporating a source electrode and a drain electrode (4) on the film (3).

2. The method for manufacturing a transistor-type photodetector based on bismuth sulfide thin film as claimed in claim 1, wherein Bi ₂ S ₃ The molar ratio of bismuth to sulfur in the precursor solution was 1: (1.5-2.5).

3. The method for manufacturing a transistor-type photodetector based on bismuth sulfide thin film as claimed in claim 1, wherein Bi ₂ S ₃ The precursor solution also comprises Na ⁺ Or Ag ⁺ 。

4. The method for manufacturing a transistor-type photodetector based on bismuth sulfide thin film as claimed in claim 3, wherein Bi ₂ S ₃ In the precursor solution, na ⁺ Or Ag ⁺ The concentration of (2) is 1% -10% of the total concentration of bismuth and sulfur.

5. The method for manufacturing a transistor type photodetector based on bismuth sulfide thin film according to claim 1, wherein the annealing at 100-300 ℃ specifically comprises:

carrying out pre-annealing treatment in an inert atmosphere, wherein the pre-annealing temperature is 60-150 ℃ and the pre-annealing time is 5-50 min;

then post annealing treatment is carried out in air, the post annealing temperature is 200 ℃ to 350 ℃, and the post annealing time is 5min to 30min.

6. The method for manufacturing a transistor-type photodetector based on bismuth sulfide thin film as claimed in claim 1, wherein said dielectric layer (2) is made of SiO ₂ 、Ta ₂ O ₅ 、Al ₂ O ₃ At least one of (a) and (b);

and/or the substrate (1) is Si or ITO.

7. The method for manufacturing a transistor-type photodetector based on bismuth sulfide thin film according to claim 1, characterized in that the thickness of the dielectric layer (2) is 50-300 nm;

and/or, the Bi ₂ S ₃ The thickness of the film (3) is 5-60 nm;

and/or the thickness of the source electrode (4) is 50-200 nm.

8. The method for manufacturing a transistor-type photodetector based on bismuth sulfide thin film as claimed in claim 1, wherein "in the Bi ₂ S ₃ The evaporation source and drain electrode (4) "on the film (3) specifically comprises:

in Bi ₂ S ₃ Evaporating metal on the film (3) to form a source electrode and a drain electrode (4);

or,

in Bi ₂ S ₃ The film (3) is firstly evaporated with C60 or MoO _x Then, metal is evaporated to form a source/drain electrode (4).

9. The method of manufacturing a bismuth sulfide thin film based transistor type photodetector according to claim 8, wherein said metal includes Ag, au, cu or Al.

10. A transistor-type photodetector based on bismuth sulfide film, characterized in that it is manufactured by the method according to any one of claims 1-9.

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