A g-CN / si heterojunction position sensitive detector and a preparation method thereof

Abstract

The application provides a g-CN / Si heterojunction position sensitive detector and a preparation method thereof. The g-CN / Si heterojunction position sensitive detector comprises a silicon substrate, a g-CN film deposited on the silicon substrate, and four electrodes arranged on the g-CN film. The preparation method comprises the following steps: (1) preparing the g-CN film on the silicon substrate by chemical vapor deposition; (2) evaporating a metal layer on the g-CN film by a thermal evaporation technology, and removing the excess metal of the metal layer by an ultraviolet lithography technology to obtain an electrode structure. The position sensitive detector has extremely high position sensitivity, and can realize real-time tracking test on a light spot position.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of detectors, in particular to a g-CN / Si heterojunction position sensitive detector and a preparation method thereof. BACKGROUND

[0002] Graphite phase carbon nitride (g-CN) is a graphite-like organic two-dimensional layered material, the in-plane structure of which extends infinitely, and the layers are stacked through van der Waals force. There are two basic structure units in the in-plane of g-CN, triazine ring and triazine ring, and the triazine structure unit is most widely studied. Unlike graphene, g-CN has an intrinsic band gap of about 2.7 eV, and is stable in physical and chemical properties and resistant to acid and alkali. g-CN has good optical performance and has strong blue fluorescence under ultraviolet light irradiation, indicating that g-CN has good light absorption characteristics. However, due to the high recombination efficiency of the material, most of the light absorbed carriers are recombined, which limits the development of the material in the field of position sensitive sub-devices.

[0003] Building a heterojunction will be an effective way to solve the problem of fast recombination of g-CN carriers. By combining it with other materials to form a heterojunction, the built-in electric field formed at the heterojunction interface will promote the rapid and efficient separation of carriers and inhibit recombination. The current widely studied synthesis method of g-CN mostly obtains a brittle powder sample, which cannot meet the process requirements of most optoelectronic devices, and there are problems such as poor surface uniformity of the prepared device and poor conductivity of the material. Synthesizing large-area high-quality g-CN thin films has great significance for the development and application of the material in the field of optoelectronic devices.

[0004] Most of the current position sensitive detectors are combined with metal nanoparticles, oxide semiconductors and organic polymers with silicon to form a heterojunction structure, thereby obtaining a position sensitive detector. However, the sensitivity of the position sensitive detector prepared by using the above-mentioned materials is generally low, generally less than 200 mV / mm. At present, two-dimensional materials have become one of the most potential materials in the next generation of nano-optoelectronics as a new type of semiconductor material. Two-dimensional materials have good mechanical flexibility, high carrier mobility, strong light and matter interaction and other characteristics. Most of the current position sensitive detectors based on two-dimensional materials are based on graphene and transition metal sulfides, and position sensitive detectors based on organic two-dimensional materials have not been reported. In our application, we use chemical vapor deposition to prepare organic two-dimensional material g-CN and apply it to the research of position sensitive detector, which broadens the application research field of the material and adds new research ideas for position sensitive detector. SUMMARY

[0005] The g-CN / Si heterojunction position sensitive detector and the preparation method thereof show extremely high position sensitive detection performance, have excellent dependence on the light spot position, and can realize real-time tracking test on the light spot position.

[0006] The technical scheme of the present application is as follows: a g-CN / Si heterojunction position sensitive detector comprises a silicon substrate, the upper side of the silicon substrate is provided with a g-CN film, and the g-CN film is provided with electrodes.

[0007] Further, the number of electrodes is 4, and the 4 electrodes are arranged in a square shape.

[0008] Further, the position sensitivity of the g-CN / Si heterojunction position sensitive detector is 340-400 mV / mm.

[0009] Further, the nonlinearity of the light position and the transverse voltage of the g-CN / Si heterojunction position sensitive detector is 0.2-1.2%.

[0010] Further, the g-CN / Si heterojunction position sensitive detector can detect light wavelengths in the range of 300-1100 nm, involving the ultraviolet-visible-near infrared region.

[0011] Further, the electrode is a gold electrode.

[0012] A preparation method of a g-CN / Si heterojunction position sensitive detector comprises the following steps:

[0013] (1) a g-CN film is prepared on a Si substrate by chemical vapor deposition;

[0014] (2) a metal layer is evaporated on the g-CN film by a thermal evaporation technique, and the excess metal of the metal layer is removed by a UV lithography technique to obtain electrodes.

[0015] Further, in step (1), the specific method for preparing the g-CN film on the Si substrate by chemical vapor deposition is as follows:

[0016] A Si substrate is used as a growth substrate, 2-10 g of melamine is placed in a first temperature zone of a tube furnace, the target temperature of the first temperature zone is 250-350 DEG C, and the heating rate is 20 DEG C / min; the Si substrate is placed in a second temperature zone of the tube furnace, the target temperature of the second temperature zone is 500-600 DEG C, and the heating rate is 20 DEG C / min; after the first temperature zone and the second temperature zone reach the target temperature, the growth time is controlled to be 5-180 min, and after the growth is completed, the temperature is naturally cooled to room temperature.

[0017] Further, in step (2), the conditions for evaporating the metal layer are as follows: the vacuum degree is 3-6*10 -4The thermal evaporation current is 40-70A, the metal evaporation source uses gold wire with a purity of 99.999%, and the evaporation time is 2-10min.

[0018] Advantages of the present application:

[0019] The g-CN / Si heterojunction structure is prepared by combining the g-CN thin film material with the silicon substrate. Due to the effect of the built-in electric field at the heterojunction interface, the separation efficiency and speed of the carriers are improved, and the recombination of the carriers is inhibited, so that the detection range is expanded to the ultraviolet, visible and near-infrared regions. The g-CN / Si heterojunction exhibits excellent position-sensitive performance, and can realize the detection of the light spot position without applying an external bias voltage, and has super-high sensitivity. Meanwhile, the g-CN / Si heterojunction position-sensitive detector realizes real-time monitoring and tracking of the moving light spot in the application of light spot tracking.

[0020] The two-dimensional g-CN thin film is grown on the p-Si substrate to constitute a heterojunction position-sensitive detector. First, the light detection range of g-CN / Si is determined. Then, the lateral photoelectric effect (LPE) research shows that the g-CN / Si heterojunction position-sensitive detector can realize the detection of the light spot position without applying an external bias voltage, and has super-high sensitivity. Meanwhile, the device is applied to the practical application of light spot tracking, and realizes real-time monitoring and tracking of the moving light spot. BRIEF DESCRIPTION OF DRAWINGS

[0021] In order to more clearly illustrate the technical solutions of the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiment or prior art description. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can also be obtained by those skilled in the art without creative labor.

[0022] Figure 1 It is a structure schematic diagram of the g-CN / Si heterojunction position-sensitive detector of the present application.

[0023] Figure 2 It is the response range of the device to light.

[0024] Figure 3 It is the position sensitivity of the device to light of different wavelengths.

[0025] Figure 4 It is the nonlinearity of the position-sensitive detector of Example 1 for detecting light of 515nm wavelength.

[0026] Figure 5For the optical tracking trajectory of the position-sensitive detector with 515nm light, the light spot moves on the device in the direction of A→B→C→D.

[0027] Figure 6 This is Example 4, showing the nonlinearity detected by a position-sensitive detector at a wavelength of 515 nm. Detailed Implementation

[0028] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0029] Example 1

[0030] like Figure 1 As shown, a g-CN / Si heterojunction position sensitive detector includes a silicon substrate, a g-CN thin film on the upper side of the silicon substrate, and electrodes disposed on the g-CN thin film. The electrodes are gold electrodes, and there are four electrodes arranged in a rectangular shape. The distance between opposite electrodes (two parallel electrodes) is 2 mm, and the ends of adjacent electrodes are spaced apart.

[0031] A method for fabricating a g-CN / Si heterojunction position-sensitive detector includes the following steps:

[0032] (1) The specific method for preparing g-CN thin films on Si substrates by chemical vapor deposition is as follows:

[0033] A Si substrate was used as the growth substrate. The substrate surface was ultrasonically cleaned sequentially with acetone, ethanol, and deionized water. Argon was used as the protective gas with a flow rate of 200 sccm. 5 g of melamine was weighed and placed in the first temperature zone of the tube furnace. The target temperature of the first temperature zone was 300℃, and the heating rate was 20℃ / min. The cleaned Si substrate was then placed in the second temperature zone of the tube furnace. The target temperature of the second temperature zone was 550℃, and the heating rate was 20℃ / min. After the first and second temperature zones reached the target temperature, the growth time was controlled at 20 min. After the growth was completed, the substrate was allowed to cool naturally to room temperature.

[0034] (2) A metal layer was deposited on the g-CN thin film by thermal evaporation. The conditions for depositing the metal layer were as follows: vacuum degree 4.1×10 -4 The thermal evaporation current is 70A, the metal evaporation source uses gold wire with a purity of 99.999%, the evaporation time is 8min, and the thickness of the gold layer is 45mm.

[0035] (3) The excess metal of the metal layer is removed by using the ultraviolet lithography technology to obtain the electrode, and the specific method is as follows:

[0036] 1) The photoresist is spin-coated on the metal layer, and the spin-coating conditions are 20s, 600r / s first, and then 50s, 5000r / s;

[0037] 2) Pre-baking: the metal layer with spin-coated photoresist is heated at 115°C for 1.5min;

[0038] 3) Photolithography: the metal layer is exposed to light using an ultraviolet lithography machine and a mask, and the exposure time is 23s;

[0039] 4) Development: the exposed metal layer is developed in a developing solution for 50s, and after the pattern appears, it is rinsed with deionized water to remove the residual developing solution, and finally dried with nitrogen;

[0040] 5) Post-baking: the developed metal layer is heated at 115°C for 30s;

[0041] 6) The metal layer is soaked in a lead iodide solution for 10s to remove excess gold, and then rinsed with deionized water;

[0042] 7) The sample is soaked in a photoresist remover for 60s to remove the photoresist covering the remaining metal layer, and then rinsed with deionized water to obtain the first electrode.

[0043] The performance of the position sensitive detector based on g-CN / Si heterojunction is studied, and it can be found from the research results that the device has excellent dependence on the position of the light spot, and the sensitivity is as high as 368mV / mm, which can realize real-time tracking test of the position of the light spot.

[0044] Figure 4 The g-CN / Si heterojunction position sensitive performance curve is shown, and from the test structure, it can be seen that the voltage across the electrodes changes linearly with the position of the light spot, and the higher the linearity, that is, the lower the nonlinearity, the higher the detection accuracy of the position of the light spot. The result of this example is 0.9%. The larger the slope of the curve, the greater the sensitivity, and the result of this example is 368mV / mm.

[0045] Figure 2 The light detection range of the tested g-CN / Si heterojunction is 300-1100nm. Figure 3 The position sensitivity when the illumination wavelength is 405, 515, 660 and 808nm respectively. Figure 5 The actual moving track of the light spot (solid line) and the detected moving track of the light spot (dot).

[0046] Example 2

[0047] This example is basically the same as example 1, except that:

[0048] A preparation method of a g-CN / Si heterojunction position sensitive detector, comprising the following steps:

[0049] (1) The specific method for preparing g-CN thin film on Si substrate by chemical vapor deposition is as follows:

[0050] Si substrate is used as growth substrate, 10g of melamine is placed in the first temperature zone of the tube furnace, the target temperature of the first temperature zone is 350℃, and the heating rate is 20℃ / min; the Si substrate is placed in the second temperature zone of the tube furnace, the target temperature of the second temperature zone is 600℃, and the heating rate is 20℃ / min; after the first temperature zone and the second temperature zone reach the target temperature, the growth time is controlled for 30min, and after the growth is completed, it is naturally cooled to room temperature.

[0051] (2) The conditions for evaporating the metal layer are as follows: vacuum degree 4×10 -4 , hot evaporation current is 70A, gold wire with purity of 99.999% is used as metal evaporation source, and evaporation time is 180min.

[0052] The g-CN / Si heterojunction position sensitive detector prepared in this example has a position sensitivity of 340mV / mm.

[0053] Example 3

[0054] This example is basically the same as example 1, except that:

[0055] A preparation method of a g-CN / Si heterojunction position sensitive detector, comprising the following steps:

[0056] (1) The specific method for preparing g-CN thin film on Si substrate by chemical vapor deposition is as follows:

[0057] Si substrate is used as growth substrate, 10g of melamine is placed in the first temperature zone of the tube furnace, the target temperature of the first temperature zone is 350℃, and the heating rate is 20℃ / min; the Si substrate is placed in the second temperature zone of the tube furnace, the target temperature of the second temperature zone is 600℃, and the heating rate is 20℃ / min; after the first temperature zone and the second temperature zone reach the target temperature, the growth time is controlled for 30min, and after the growth is completed, it is naturally cooled to room temperature.

[0058] (2) The conditions for evaporating the metal layer are as follows: vacuum degree 4×10 -4 , hot evaporation current is 70A, gold wire with purity of 99.999% is used as metal evaporation source, and evaporation time is 180min.

[0059] The g-CN / Si heterojunction position sensitive detector prepared in the embodiment, the g-CN / Si heterojunction position sensitive detector prepared in the embodiment, the position sensitivity is 380 mV / mm.

[0060] Embodiment 4

[0061] The embodiment is basically the same as embodiment 1, and the difference is that:

[0062] A preparation method of a g-CN / Si heterojunction position sensitive detector, comprising the following steps:

[0063] (1) The specific method for preparing a g-CN film on a Si substrate by chemical vapor deposition is as follows:

[0064] Si substrate is used as a growth substrate, 5g of melamine is placed in the first temperature zone of the tube furnace, the target temperature of the first temperature zone is 350 DEG C, and the heating rate is 20 DEG C / min; the Si substrate is placed in the second temperature zone of the tube furnace, the target temperature of the second temperature zone is 500 DEG C, and the heating rate is 20 DEG C / min; after the first temperature zone and the second temperature zone reach the target temperature, the growth time is controlled for 20 min, and after the growth is completed, it is naturally cooled to room temperature;

[0065] (2) The conditions for evaporating the metal layer are as follows: vacuum degree 4.1*10 -4 , the hot evaporation current is 70A, the metal evaporation source uses gold wire with a purity of 99.999%, and the evaporation time is 5 min.

[0066] The g-CN / Si heterojunction position sensitive detector prepared in the embodiment, the g-CN / Si heterojunction position sensitive detector prepared in the embodiment, the position sensitivity is 400 mV / mm, as shown in Figure 6 The figure shows the g-CN / Si heterojunction position sensitive performance curve, from the test structure, it can be seen that the voltage between the electrodes changes linearly with the position of the light spot, and the higher the linearity, that is, the lower the nonlinearity, indicates that the detection accuracy of the light spot position is higher, and the nonlinearity of the embodiment is 0.3%.

[0067] The above only describes the preferred embodiments of the present application and is not intended to limit the present application, and any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. A g-CN / Si heterojunction position-sensitive detector, characterized in that: It includes a silicon substrate, a g-CN thin film on the upper side of the silicon substrate, and an electrode on the upper side of the g-CN thin film; There are four electrodes, arranged in a square. The position sensitivity of the g-CN / Si heterojunction position-sensitive detector is 340-400 mV / mm; The g-CN / Si position-sensitive detector has a detection range of 300-1100 nm for light wavelengths. g-CN thin films were prepared on Si substrates using chemical vapor deposition, as follows: Using a Si substrate as the growth substrate, 2-10g of melamine was weighed and placed in the first temperature zone of the tube furnace. The target temperature of the first temperature zone was 250-350℃, and the heating rate was 20℃ / min. The Si substrate was then placed in the second temperature zone of the tube furnace. The target temperature of the second temperature zone was 500-600℃, and the heating rate was 20℃ / min. After the first and second temperature zones reached the target temperature, the growth time was controlled to be 5-180 min. After the growth was completed, the substrate was allowed to cool naturally to room temperature.

2. The g-CN / Si heterojunction position-sensitive detector according to claim 1, characterized in that: The electrodes are gold electrodes.

3. A method for fabricating a g-CN / Si heterojunction position-sensitive detector as described in claim 1 or 2, characterized in that, Includes the following steps: (1) g-CN thin films were prepared on Si substrates by chemical vapor deposition; (2) A metal layer is deposited on the g-CN thin film by thermal evaporation technology, and the excess metal in the metal layer is removed by ultraviolet lithography to obtain the electrode.

4. The preparation method according to claim 3, characterized in that, In step (2), the conditions for depositing the metal layer are as follows: vacuum degree 3×10 -4 -6×10 -4 The thermal evaporation current is 40-70 A, the metal evaporation source uses gold wire with a purity of 99.999%, and the evaporation time is 2-10 min.

Images