阅读说明：本技术 一种浮栅控制型近红外波段双向记忆的光电存储器及其制备方法 (Floating gate control type near-infrared band bidirectional memory photoelectric memory and preparation method thereof ) 是由 王军 韩兴伟 韩超 韩嘉悦 刘澍锴 范书铭 李浩杰 于 2021-01-15 设计创作，主要内容包括：本发明属于光电存储器领域,具体公开了一种浮栅控制型近红外波段双向记忆的光电存储器及其制备方法,光电存储器包括从下至上依次设置的衬底层、浮栅层、介质层、导电沟道层和金属电极,所述浮栅层材料为富勒烯,用于存储载流子；所述导电沟道层吸收近红外光和提供导电沟道；所述介质层为大带隙绝缘材料,所述介质层与所述浮栅层之间形成势垒,所述介质层(3)与所述导电沟道层(4)之间形成势垒。在所述衬底层(1)和所述源电极(5)之间施加正向的电压时,所述浮栅层(2)中注入电子；在所述衬底层(1)和所述源电极(5)之间施加负向的电压时,所述浮栅层(2)中注入空穴,实现了近红外波段可调制的双向记忆的存储效果。(The invention belongs to the field of photoelectric memories, and particularly discloses a floating gate control type near-infrared band two-way memory photoelectric memory and a preparation method thereof, wherein the photoelectric memory comprises a substrate layer, a floating gate layer, a dielectric layer, a conductive channel layer and a metal electrode which are sequentially arranged from bottom to top, and the floating gate layer is made of fullerene and is used for storing current carriers; the conductive channel layer absorbs the near-infrared light and provides a conductive channel; the dielectric layer is made of a large-band-gap insulating material, a potential barrier is formed between the dielectric layer and the floating gate layer, and a potential barrier is formed between the dielectric layer (3) and the conductive channel layer (4). When a forward voltage is applied between the substrate layer (1) and the source electrode (5), electrons are injected into the floating gate layer (2); when negative voltage is applied between the substrate layer (1) and the source electrode (5), holes are injected into the floating gate layer (2), and the storage effect of bidirectional memory which can be modulated in the near-infrared band is achieved.)

1. The utility model provides a photoelectric memory of near-infrared wave band two-way memory of floating gate control type, includes substrate layer (1), floating gate layer (2), dielectric layer (3), electrically conductive channel layer (4) and the metal electrode that sets gradually from supreme down, its characterized in that:

the floating gate layer (2) is made of fullerene and is used for storing current carriers; the conductive channel layer (4) absorbs near-infrared light and provides a conductive channel; the dielectric layer (3) is made of a large-band-gap insulating material, a potential barrier is formed between the dielectric layer (3) and the floating gate layer (2), and a potential barrier is formed between the dielectric layer (3) and the conductive channel layer (4).

2. The floating gate controlled near-infrared band two-way memory photoelectric memory according to claim 1, characterized in that:

the dielectric layer (3) is made of hexagonal boron nitride, and the conducting channel layer (4) is made of graphene.

3. The floating gate controlled near-infrared band two-way memory photoelectric memory according to claim 1, characterized in that:

the substrate layer (1) is an oxygen silicon film and is used for grid voltage input.

4. The floating gate controlled near-infrared band two-way memory photoelectric memory according to claim 3, characterized in that:

the medium layer (3) is completely coated on the floating gate layer (2).

5. The floating gate controlled near-infrared band two-way memory photoelectric memory according to claim 4, characterized in that:

the metal electrodes include a source electrode (5) and a drain electrode (6) respectively disposed on the conductive channel layer (4).

6. The floating gate controlled near-infrared band two-way memory photoelectric memory according to claim 5, characterized in that:

the gate voltage input includes: when a forward voltage is applied between the substrate layer (1) and the source electrode (5), electrons are injected into the floating gate layer (2); when a negative voltage is applied between the substrate layer (1) and the source electrode (5), holes are injected into the floating gate layer (2).

7. The method for preparing the floating gate control type near-infrared band two-way memory photoelectric memory of any one of claims 1 to 6, characterized in that: the method comprises the following steps:

s1, preparing a substrate layer (1), cleaning the substrate layer (1) and airing;

s2, evaporating and plating a layer of fullerene film on the cleaned and dried substrate layer (1) to be used as a floating gate layer (2);

s3, preparing a layer of large-band-gap insulating material on the floating gate layer (2) to serve as a dielectric layer (3);

s4, preparing a conductive channel layer (4) on the dielectric layer (3), and evaporating a metal electrode on the conductive channel layer (4) to finish the preparation of the device.

8. The method for preparing a floating gate control type near-infrared band two-way memory photoelectric memory according to claim 7, characterized in that:

the substrate layer (1) is an oxygen silicon film, and the step of cleaning the substrate layer (1) in the step S1 comprises the following steps: and ultrasonically cleaning the silicon oxide film by using a detergent, acetone, ethanol and deionized water in sequence.

9. The method for preparing a floating gate control type near-infrared band two-way memory photoelectric memory according to claim 7, characterized in that:

the dielectric layer (3) is made of hexagonal boron nitride, the dielectric layer (3) is completely coated on the floating gate layer (2), and the conductive channel layer (4) is located right above the floating gate layer (2).

10. The method for preparing a floating gate control type near-infrared band two-way memory photoelectric memory according to claim 7, characterized in that:

the graphene is selected as the material of the conductive channel layer (4), the conductive channel layer (4) is located right above the floating gate layer (2), and the metal electrode comprises a source electrode (5) and a drain electrode (6) which are respectively arranged on the conductive channel layer (4).

Technical Field

The invention relates to the field of photoelectric memories, in particular to a floating gate control type near-infrared band bidirectional memory photoelectric memory and a preparation method thereof.

Background

The fullerene molecule is composed of 60 carbon atoms, and is similar to football in structure, so that the fullerene is also called football, and is a stable molecule combined by carbon atoms according to the structure. The stable structure of carbon atoms formed by fullerenes has been noted as attracting attention and interest once it has been discovered. Fullerene is a more desirable electron acceptor because of its structural lack of electron-olefins, and undoped fullerene is a weak n-type semiconductor. The fullerene molecule has excellent electron affinity, so that the fullerene molecule has the capability of storing electrons, and therefore, the fullerene molecule can be used as a floating gate layer material in a floating gate control photoelectric memory. Graphene is a single-atom layered two-dimensional material, carbon atoms are arranged in a hexagonal honeycomb lattice, and the material has many attractive electronic, optical, mechanical and thermal properties, and has the advantages of being light and thin, good in heat and electric conductivity and stable in properties. At normal temperature, the carrier mobility of graphene is about 10⁵cm²Vs, at low temperatures up to 10⁶cm²Vs. The graphene has the characteristics of zero band gap and half-metallic property, the characteristic is very promising for the application of the graphene in the photoelectric field, and the light absorption coefficient of the single-layer graphene in the range from visible light to near infrared light can reach 7x10⁵cm^-1This coefficient is much higher than other conventional semiconductor materials. The hexagonal boron nitride is a two-dimensional material which is composed of nitrogen atoms and boron atoms and is similar to a graphene hexagonal honeycomb lattice structure, but is different from graphene in that the hexagonal boron nitride is an insulator with a large band gap of 6eV and has a lattice constant very similar to that of graphene, so that the hexagonal boron nitride has a promising application in a functional device combined with the graphene and is commonly used as a dielectric layer material.

At present, the floating gate control type photoelectric memory device is mainly composed of a stack structure of a floating gate layer, a dielectric layer and a conductive channel, current carriers are injected into the floating gate layer through gate voltage, devices at two ends are also injected through source-drain bias voltage, resistance of the conductive channel is regulated and controlled by using a floating gate effect formed by the current carriers blocked by the dielectric layer, current of the conductive channel is changed, the current state is kept, and a memory effect on the current is formed. And then, injecting carriers with opposite electric properties through opposite gate voltage or opposite source-drain bias voltage to enable the carriers stored in the floating gate to be compounded, so that the floating gate effect disappears correspondingly, and the current in the conductive channel returns to the initial state. In addition, the electric memory can be erased by illumination, and the light absorption layer can be a floating gate layer or a conductive channel layer. When the floating gate layer material absorbs light to excite the stored carriers to tunnel so as to restore the initial state, when the conducting channel light absorption material absorbs light to generate photon-generated carriers, part of the carriers are excited to tunnel through the dielectric layer to enter the floating gate layer and to be compounded with the stored carriers, and the initial state is restored. In 2016, the two-end floating gate control type photoelectric memory manufactured by combining three two-dimensional materials realizes electric injection and electric erasing, and on the basis, the Quoc An Vu and the like research the optical erasing effect of the device in 2018 and realize the optical erasing in a visible light range; yu Wang in 2018 researches the influence of different gate voltage electric injection on the light erasing effect of the device, when the gate voltage is positive and negative, the injected carriers have different electrical properties, and the response directions are different during light erasing, but the light erasing wave band is limited to the visible light wave band; wenhao Huang and Sung Hyun Kim in 2019 respectively explore the light erasing phenomenon of the devices, but the influence of changing the positive and negative response of gate voltage injection to light erasing is not explored all the time, and the light erasing waveband is still limited to the visible light waveband.

At present, the floating gate control type photoelectric memory devices have common problems: on one hand, most of carriers injected electrically are limited to be injected unidirectionally, and the positive and negative response of the optical erasing effect is difficult to change by controlling the positive and negative values of the grid voltage; on the other hand, the light band of the optical erasing is limited to the visible light band due to the limitation of the light absorption material, and the near infrared band is difficult to be widened.

Disclosure of Invention

The invention mainly provides a floating gate control type near-infrared waveband two-way memory photoelectric memory and a preparation method thereof, which can solve the problems that the optical memory waveband of the existing floating gate control type photoelectric memory is limited by the properties of light absorption materials, a floating gate and conducting channel materials, only the optical memory of a visible light waveband can be realized, only the one-way injection of forward electric injection or reverse electric injection can be realized, and the storage of the near-infrared waveband two-way memory and the positive-negative response conversion of optical erasing are difficult to realize.

In order to solve the technical problems, the invention provides a floating gate control type near-infrared band bidirectional memory photoelectric memory.

The photoelectric memory comprises a substrate layer 1, a floating gate layer 2, a dielectric layer 3, a conductive channel layer 4 and a metal electrode which are sequentially arranged from bottom to top, wherein the floating gate layer 2 is made of fullerene and is used for storing current carriers; the conductive channel layer 4 absorbs near infrared light and provides a conductive channel; the dielectric layer 3 is made of a large band gap insulating material, a potential barrier is formed between the dielectric layer 3 and the floating gate layer 2, and a potential barrier is formed between the dielectric layer 3 and the conductive channel layer 4.

Preferably, the dielectric layer 3 is made of hexagonal boron nitride, and the conductive channel layer 4 is made of graphene.

Preferably, the substrate layer 1 is an oxygen silicon film for gate voltage input.

Preferably, the dielectric layer 3 completely covers the floating gate layer 2.

Preferably, the metal electrodes include a source electrode 5 and a drain electrode 6 respectively disposed on the conductive channel layer 4.

Preferably, the gate voltage input comprises: when a forward voltage is applied between the substrate layer 1 and the source electrode 5, electrons are injected into the floating gate layer 2; when a negative voltage is applied between the substrate layer 1 and the source electrode 5, holes are injected into the floating gate layer 2.

The invention also provides a preparation method of the floating gate control type near-infrared waveband two-way memory photoelectric memory, which comprises the following steps:

s1, preparing a substrate layer 1, cleaning the substrate layer 1 and drying;

s2, evaporating and plating a layer of fullerene film on the substrate layer 1 after cleaning and airing to be used as a floating gate layer 2;

s3, preparing a layer of large band gap insulating material on the floating gate layer 2 to serve as a dielectric layer 3;

s4, preparing a conductive channel layer 4 on the dielectric layer 3, and evaporating a metal electrode on the conductive channel layer 4 to finish the preparation of the device.

Preferably, the substrate layer 1 is an oxygen-silicon thin film, and the step of cleaning the substrate layer 1 in S1 includes: and ultrasonically cleaning the silicon oxide film by using a detergent, acetone, ethanol and deionized water in sequence.

Preferably, the dielectric layer 3 is made of hexagonal boron nitride, the dielectric layer 3 is completely coated on the floating gate layer 2, and the conductive channel layer 4 is located right above the floating gate layer 2.

Preferably, the material of the conductive channel layer 4 is graphene, the conductive channel layer 4 is located right above the floating gate layer 2, and the metal electrode includes a source electrode 5 and a drain electrode 6 respectively disposed on the conductive channel layer 4.

The invention has the beneficial effects that: (1) different from the situation of the prior art, the invention is sequentially provided with a substrate layer 1, a floating gate layer 2, a dielectric layer 3, a conductive channel layer 4 and a metal electrode from bottom to top, wherein the floating gate layer 2 is made of fullerene and is used for storing current carriers so that electrons or holes can be stored after electricity is injected, the dielectric layer 3 is made of a large-band-gap insulating material, potential barriers are formed between the dielectric layer 3 and the floating gate layer 2 and between the dielectric layer 3 and the conductive channel layer 4 to prevent the current carriers from moving between the floating gate layer 2 and the conductive channel layer 4, so that the current carriers injected into the floating gate layer 2 can be effectively stored, when the gate voltage is positive, electrons are injected into the floating gate layer 2, and the near infrared light irradiates the conductive channel layer 4 to excite hole tunneling to; when the grid voltage is negative, injecting holes into the floating grid layer 2, and irradiating the conductive channel layer 4 by the near infrared light to stimulate electron tunneling to be compounded with the holes, so as to realize the storage effect of bidirectional memory capable of modulating the near infrared wave band; (2) the medium layer 3 is completely coated on the floating gate layer 2, so that the floating gate layer can isolate the influence of the external environment and has the durable characteristic which is not possessed by other memories adopting organic materials; (3) the graphene is used as the conductive channel layer 4, and the graphene has high mobility, so that the current change between a source and a drain can be effectively represented; the graphene absorbs light in a near-infrared band, and compared with the fact that the light absorption range of most semiconductors is limited in a visible light range, the light absorption range of the floating gate control type photoelectric memory can be widened to the near-infrared band; (4) the material of the floating gate layer 2 is fullerene, the material of the dielectric layer 3 is hexagonal boron nitride, the material of the conductive channel layer 4 is graphene, crystal lattices of the three have good lattice matching, interface defects are few, and the stability of the device is improved.

Drawings

FIG. 1 is a schematic structural diagram of a floating gate control type near-infrared band two-way memory photoelectric memory according to the present invention;

FIG. 2 is a schematic illustration of the energy bands of the present invention;

FIG. 3 is a schematic illustration of the positive gate voltage injection forming negative photoresponse carrier transport of the present invention;

FIG. 4 is a schematic illustration of the negative gate voltage injection forming positive photoresponse carrier transport of the present invention;

FIG. 5 is a schematic representation of near infrared light response positive and negative flips formed by different gate voltage injections according to the present invention;

FIG. 6 is a diagram of the near infrared long term memory of the present invention.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention clearer and more complete, the following embodiments are further illustrated in the accompanying drawings.

Example 1

As shown in fig. 1, a floating gate control type near-infrared band two-way memory photoelectric memory is provided. The photoelectric memory comprises a substrate layer 1, a floating gate layer 2, a dielectric layer 3, a conductive channel layer 4 and a metal electrode which are sequentially arranged from bottom to top, wherein the floating gate layer 2 is made of fullerene and is used for storing current carriers; the conductive channel layer 4 absorbs near infrared light and provides a conductive channel; the dielectric layer 3 is made of a large band gap insulating material, a potential barrier is formed between the dielectric layer 3 and the floating gate layer 2, and a potential barrier is formed between the dielectric layer 3 and the conductive channel layer 4.

The working principle of the invention is as follows: the material of the floating gate layer 2 is fullerene which can effectively store electrons or holes which are injected from gate voltage and tunneled from the conductive channel layer to the floating gate layer, the medium layer 3 is a large band gap insulating material, potential barriers are formed between the medium layer 3 and the floating gate layer 2 and between the medium layer and the conducting channel layer 4 to prevent carriers from moving between the floating gate layer 2 and the conducting channel layer 4, the initial source leakage current state is difficult to recover by reverse tunneling after the gate voltage control tunneling is finished, so that the current carriers injected into the floating gate layer 2 can be effectively stored, the floating gate layer 2 enables the photoelectric memory to form a complete floating gate structure, the current magnitude of the conducting channel is changed by utilizing the floating gate effect of the floating gate layer 2 so as to achieve the effects of memory and erasure, the conducting channel layer 4 can absorb near infrared light, when the grid voltage is positive, electrons are injected into the floating grid layer 2, and the near infrared light irradiates the conductive channel layer 4 to excite hole tunneling to be compounded with the hole tunneling; when the grid voltage is negative, holes are injected into the floating grid layer 2, the near infrared light irradiates the conductive channel layer 4 to stimulate electron tunneling to be combined with the holes, and therefore the bidirectional memory storage effect that the near infrared wave band can be modulated is achieved.

Further, the dielectric layer 3 is made of hexagonal boron nitride, and the conductive channel layer 4 is made of graphene.

Further, as shown in the energy band structure of fig. 2, a dielectric layer hexagonal boron nitride with a large band gap is arranged between the fullerene thin film and the graphene of the conducting channel layer, and due to the blocking effect of the dielectric layer 3, the carriers are difficult to tunnel beyond the large barrier without external excitation. When positive voltage is applied between the grid electrode and the source electrode, as shown in fig. 3, a large amount of electrons are injected into the graphene, the fermi level of the graphene is increased, the electrons tunnel to the fullerene, after the application of the grid voltage is stopped, the electrons cannot tunnel to the graphene reversely due to barrier blocking, so that the resistance level of the graphene is reduced, the source-drain current value is increased, when the graphene is irradiated by near-infrared light, photo-generated holes in the graphene are stimulated to tunnel to the fullerene to be compounded with the stored electrons, the floating gate effect disappears, the source-drain current returns to the initial state, the illumination photocurrent is negative response, and the current is continuously maintained after the illumination is finished, so that the optical memory of the negative response is realized; when negative pressure is applied between the gate and the source, as shown in fig. 4, a large number of holes are injected into the graphene, the fermi level of the graphene is reduced, the holes tunnel to the fullerene, after the application of the gate voltage is stopped, the holes cannot tunnel to the graphene in a reverse direction due to barrier blocking, so that the resistance level of the graphene is increased, the source-drain current value is reduced, the source-drain current value is irradiated by near infrared light, photo-generated electrons in the graphene are excited to tunnel to the fullerene to be compounded with the stored holes, the floating gate effect disappears, the source-drain current returns to the initial state, the illumination photocurrent is positive response, and the current is continuously maintained after the illumination is finished, so that the optical memory of the positive response is realized.

Further, the substrate layer 1 is an oxygen silicon film and is used for gate voltage input.

Further, the medium layer 3 completely covers the floating gate layer 2.

Further, the metal electrodes include a source electrode 5 and a drain electrode 6 respectively disposed on the conductive channel layer 4.

Further, the gate voltage input includes: when a forward voltage is applied between the substrate layer 1 and the source electrode 5, electrons are injected into the floating gate layer 2; when a negative voltage is applied between the substrate layer 1 and the source electrode 5, holes are injected into the floating gate layer 2.

Example 2

The invention also provides a preparation method of the floating gate control type near-infrared waveband two-way memory photoelectric memory, which comprises the following steps:

s1, preparing a substrate layer 1, cleaning the substrate layer 1 and drying;

s2, evaporating and plating a layer of fullerene film on the substrate layer 1 after cleaning and airing to be used as a floating gate layer 2;

s3, preparing a layer of large band gap insulating material on the floating gate layer 2 to serve as a dielectric layer 3;

s4, preparing a conductive channel layer 4 on the dielectric layer 3, and evaporating a metal electrode on the conductive channel layer 4 to finish the preparation of the device.

Further, the substrate layer 1 is made of an oxygen-silicon thin film, and the step of cleaning the substrate layer 1 in S1 includes: and ultrasonically cleaning the silicon oxide film by using a detergent, acetone, ethanol and deionized water in sequence.

Furthermore, the material of the dielectric layer 3 is hexagonal boron nitride, the dielectric layer 3 is completely coated on the floating gate layer 2, and the conductive channel layer 4 is located right above the floating gate layer 2.

Furthermore, the material of the conductive channel layer 4 is graphene, the conductive channel layer 4 is located right above the floating gate layer 2, and the metal electrode comprises a source electrode 5 and a drain electrode 6 which are respectively arranged on the conductive channel layer 4.

Example 3

On the basis of the embodiment 1, when the injection grid voltage is changed in size and positive and negative, different photoresponse sizes are generated.

As shown in fig. 5, different injection gate voltages cause different optical responses, and when the absolute magnitude of the gate voltage is increased, the response magnitude is also increased, because the larger the gate voltage is, the more carriers are injected, and the larger the current change is caused; when the gate voltage changes, the direction of the photoresponse also changes, since the electrical properties of the injected carriers change, forming the opposite photoresponse.

Example 4

When the injection grid voltage is fixed, a stable optical memory is formed. As shown in FIG. 6, when 60V positive grid voltage is injected, a negative response is formed after 30 seconds of near-infrared illumination, and after the illumination is finished, the current state after injection is not recovered, but the state is maintained, and the state maintaining time can reach 10⁴The time is more than second, so that the long-time memory of the near infrared light is realized.

The above description is only an embodiment of the present invention, and not intended to limit the scope of the present invention, and all modifications of equivalent structures and equivalent processes performed by the present specification and drawings, or directly or indirectly applied to other related technical fields, are included in the scope of the present invention.