Reconfigurable optoelectronic logic gate based on pyroelectric effect of hafnium-based ferroelectric thin film

Abstract

The application discloses a reconfigurable photoelectric logic gate based on pyroelectric effect of hafnium-based ferroelectric thin film, which comprises a substrate, two devices with the same structure symmetrically arranged on the left and right sides of the substrate, the device comprising a top electrode, an intermediate layer and a bottom electrode arranged in sequence from top to bottom, and the intermediate layer adopting a ferroelectric thin film; an external bias voltage is applied on the top electrode of the two devices, and the bottom electrode of the two devices is grounded; a laser emitter is arranged above the device; by using the pyroelectric effect of the ferroelectric thin film, the device controls the polarization direction and the residual polarization strength of the ferroelectric thin film by adjusting the external bias voltage, thereby adjusting the pyroelectric current response and realizing the operation of five kinds of logic gates. The application can realize the dynamic logic reconfiguration of the device by adjusting the external bias voltage to control the ferroelectric polarization direction and the residual polarization strength in real time, so that the same device can dynamically switch five kinds of logic functions without changing the hardware.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of integrated circuits, in particular to a reconfigurable optoelectronic logic gate based on pyroelectric effect of hafnium-based ferroelectric thin film. BACKGROUND

[0002] Optoelectronic logic gates are attracting extensive attention and becoming the key components for precise and fast data processing in future integrated circuits. Due to the insufficient performance in switching, operation, computation and decision / regeneration, existing circuits or processors based on electronic logic gates will face limitations when dealing with large data sets, so it is crucial to develop an innovative logic gate platform that can achieve faster computation with lower power consumption.

[0003] Since ferroelectricity has been successfully demonstrated in doped hafnium oxide (HfO2) thin films, this classic material has attracted extensive attention and is considered as an ideal candidate for potential applications. Compared with traditional perovskite structure ferroelectric thin films, HfO2-based ferroelectric thin films have excellent characteristics such as high compatibility with complementary metal-oxide-semiconductor (CMOS), significant polarization amplitude and excellent radiation resistance, which make it an ideal new type of ferroelectric thin film material. One attractive feature of HfO2-based ferroelectric thin films is their pyroelectric effect, which is closely related to the temperature dependence of ferroelectric thin film polarization. In fact, the pyroelectric effect is an important mechanism for sensing photon irradiation and has been widely used in practical sensing fields such as infrared detection and thermal imaging. In addition, the pyroelectric behavior of HfO2-based ferroelectric thin films can be adjusted by electric field regulation of dipole orientation, which lays a physical foundation for its application in reconfigurable optoelectronic logic gates.

[0004] In the prior art, most of the basic principles of optoelectronic logic gates are to utilize the photoelectric effect. Due to the limitation of the band gap, there is a relatively large limitation on the wavelength of light, however, the pyroelectric current response is essentially caused by the change of thin film temperature, which greatly broadens the selection of input light wavelength. SUMMARY

[0005] In order to solve the above technical problems, the present application provides a reconfigurable optoelectronic logic gate based on pyroelectric effect of hafnium-based ferroelectric thin film, which has simple structure and wide application range.

[0006] The technical scheme for solving the above technical problems of the present application is: a reconfigurable optoelectronic logic gate based on pyroelectric effect of hafnium-based ferroelectric thin film, comprising a substrate, two devices with the same structure symmetrically arranged on the left and right sides of the substrate, the device comprising a top electrode, an intermediate layer and a bottom electrode arranged in sequence from top to bottom, and the intermediate layer adopting a ferroelectric thin film; an external bias voltage is applied to the top electrode of the two devices, and the bottom electrode of the two devices is grounded; a laser emitter is arranged above the device, under near-infrared laser irradiation, the surface temperature of the device changes, and then a pyroelectric current is generated, and the generated pyroelectric current is converted into a high level or a low level output after being processed by a negative feedback circuit; by using the pyroelectric effect of the ferroelectric thin film, the device controls the polarization direction and the residual polarization strength of the ferroelectric thin film by adjusting the external bias voltage, thereby adjusting the pyroelectric current response, realizing the operation of five kinds of logic gates, and the five kinds of logic gates include: AND gate, OR gate, NAND gate, NOR gate and NOT gate.

[0007] The reconfigurable optoelectronic logic gate based on pyroelectric effect of hafnium-based ferroelectric thin film, the external bias voltage includes a positive bias and a negative bias, the positive bias and the negative bias are used to control the positive polarization and the negative polarization state of the device, and then different logic functions are realized.

[0008] The reconfigurable optoelectronic logic gate based on pyroelectric effect of hafnium-based ferroelectric thin film, when a positive bias pulse of +1.8V to +5V is applied, the device works in the positive polarization direction, and the AND gate and the OR gate both work in the positive polarization direction, that is, a positive pyroelectric current is generated at the moment of light irradiation.

[0009] If the bias voltage is not continuously applied, the reconfigurable optoelectronic logic gate is an AND gate, for the AND gate, when the input logic is 00, 01 or 10, the pyroelectric current generated by the device is lower than the baseline current, and the output logic is 0; when the input logic is 11, the pyroelectric current generated by the device is higher than the baseline current, and the corresponding output logic is 1.

[0010] If a +300 mV bias voltage is continuously applied to modulate the current of the device, the current is adjusted to +7 nA·cm -2 , the reconfigurable optoelectronic logic gate is an OR gate, for the OR gate, when the input logic is 00, the pyroelectric current generated by the device is lower than the baseline current, and the output logic is 0; when the input logic is 01, 10 or 11, the pyroelectric current generated by the device is higher than the baseline current, and the corresponding output logic is 1.

[0011] The reconfigurable optoelectronic logic gate based on pyroelectric effect of hafnium-based ferroelectric thin film, when a negative bias pulse of -1.8V to -5V is applied, the device works in the negative polarization direction, and the NAND gate, the NOR gate and the NOT gate all work in the negative polarization direction, that is, a negative pyroelectric current is generated at the moment of light irradiation.

[0012] If the current of the device is modulated by continuously applying a +400 mV bias, the current is adjusted to +37nA·cm -2 , the reconfigurable optoelectronic logic gate can be a NOR gate. For the NOR gate, when the input logic is 00, the pyroelectric current generated by the device is higher than the baseline current, and the output logic is 1; when the input logic is 01, 10 or 11, the pyroelectric current generated by the device is lower than the baseline current, and the corresponding output logic is 0.

[0013] If the current of the device is modulated by continuously applying a +450 mV bias, the current is adjusted to +52nA·cm -2 , the reconfigurable optoelectronic logic gate can be a NOT gate. For the NOT gate, only two input states are involved, and a double optical path synchronous switch is used for simulation. When the input logic is 00, the pyroelectric current generated by the device is higher than the baseline current, and the output logic is 1; when the input logic is 11, the pyroelectric current generated by the device is lower than the baseline current, and the corresponding output logic is 0.

[0014] If the current of the device is modulated by continuously applying a +500 mV bias, the current is adjusted to +61nA·cm -2 , the reconfigurable optoelectronic logic gate can be a NAND gate. For the NAND gate, when the input logic is 00, 01 or 10, the pyroelectric current generated by the device is higher than the baseline current, and the output logic is 1; when the input logic is 11, the pyroelectric current generated by the device is lower than the baseline current, and the corresponding output logic is 0.

[0015] The reconfigurable optoelectronic logic gate based on the pyroelectric effect of hafnium-based ferroelectric thin film has one of hafnium zirconium oxide, bismuth titanate or lead zirconium titanate as the intermediate layer material, and one of titanium nitride, gold, platinum or tungsten as the top electrode and bottom electrode material.

[0016] The reconfigurable optoelectronic logic gate based on the pyroelectric effect of hafnium-based ferroelectric thin film has two near-infrared laser light input signals, wherein the on-state light input represents logic 1 and the off-state light input represents logic 0, and the function of a double-input logic gate is realized by adjusting the on-off state of the two light signals.

[0017] The reconfigurable optoelectronic logic gate based on the pyroelectric effect of hafnium-based ferroelectric thin film has a hafnium zirconium oxide thin film as the ferroelectric thin film, which is deposited at 100°C by atomic layer deposition (ALD) process to ensure compatibility with CMOS process.

[0018] The reconfigurable optoelectronic logic gate based on the pyroelectric effect of hafnium-based ferroelectric thin film has a hafnium zirconium oxide thin film as the ferroelectric thin film, which is deposited at 100°C by atomic layer deposition (ALD) process to ensure compatibility with CMOS process.

[0019] The reconfigurable photoelectric logic gate based on pyroelectric effect of hafnium-based ferroelectric thin film has the negative feedback circuit comprising a current amplifier and a current conversion circuit, which is used for converting the pyroelectric current into identifiable digital logic signals.

[0020] The present application has the following beneficial effects:

[0021] 1. Wide spectrum response characteristics: The present application uses pyroelectric effect to replace traditional photoelectric effect, breaks through the limitation of material band gap on light wavelength, realizes high sensitivity response to near-infrared to mid-infrared waveband, and uses pyroelectric current response for logic operation, and has wide spectrum response characteristics.

[0022] 2. Dynamic logic reconfiguration capability: The present application can realize dynamic logic reconfiguration of the device by adjusting the external bias voltage to control the ferroelectric polarization direction and the remanent polarization strength in real time, so that the same device can dynamically switch the AND, OR, NAND, NOR and NOT five kinds of logic functions without changing the hardware.

[0023] 3. Process compatibility and energy efficiency advantage: The hafnium-zirconium-oxygen (HZO) ferroelectric thin film based on ultra-low temperature (100℃) atomic layer deposition ALD process is compatible with CMOS back-end process, and is suitable for high energy efficiency photoelectric integrated system. BRIEF DESCRIPTION OF DRAWINGS

[0024] Figure 1 It is a structural schematic diagram of the present application.

[0025] Figure 2 It is a uniform glue schematic diagram.

[0026] Figure 3 It is a bottom electrode deposition schematic diagram.

[0027] Figure 4 It is a patterned bottom electrode schematic diagram.

[0028] Figure 5 It is a patterned middle layer schematic diagram.

[0029] Figure 6 It is a patterned top metal electrode schematic diagram.

[0030] Figure 7 It is a working state schematic diagram of the reconfigurable photoelectric logic gate.

[0031] Figure 8 It is a working principle schematic diagram of the reconfigurable photoelectric logic gate.

[0032] Figure 9 It is a peripheral circuit schematic diagram of the reconfigurable photoelectric logic gate.

[0033] Figure 10 It is an implementation schematic diagram of the AND gate.

[0034] Figure 11 This is a schematic diagram of the OR gate implementation.

[0035] Figure 12 This is a schematic diagram of the implementation of a NAND gate.

[0036] Figure 13 This is a schematic diagram of the implementation of a NOR gate.

[0037] Figure 14 This is a schematic diagram of the implementation of the NOT gate.

[0038] In the figure, 1 is photoresist, 2 is bottom electrode, 3 is intermediate layer, 4 is top electrode, 5 is substrate, and 6 is laser emitter. Detailed Implementation

[0039] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0040] like Figure 1 As shown, a reconfigurable optoelectronic logic gate based on the pyroelectric effect of hafnium-based ferroelectric thin films includes a substrate 5 made of silicon dioxide. Two identical devices are symmetrically arranged on the left and right sides of the substrate 5. Each device includes a top electrode 4, an intermediate layer 3, and a bottom electrode 2 arranged sequentially from top to bottom. Both the top electrode 4 and the bottom electrode 2 are made of tungsten metal with a thickness of 20 nm. The intermediate layer 3 is made of hafnium zirconium oxide thin film, i.e., HZO. A thin film is used; an external bias voltage is applied to the top electrodes 4 of the two devices, and the bottom electrodes 2 of the two devices are grounded; a laser emitter 6 is placed above the devices. Under near-infrared laser irradiation, the surface temperature of the devices changes, thereby generating a pyroelectric current. The generated pyroelectric current is processed by a negative feedback circuit and converted into a high-level or low-level output. Utilizing the pyroelectric effect of the ferroelectric thin film, the device controls the polarization direction and residual polarization intensity of the ferroelectric thin film by adjusting the external bias voltage, thereby regulating the pyroelectric current response and realizing the operation of five logic gates: AND gate; OR gate; NAND gate; NOR gate; and NOT gate. The input optical signals of the device are two near-infrared lasers, where the on state of the optical input represents logic 1 and the off state of the optical input represents logic 0. The dual-input logic gate function is realized by adjusting the on / off state of the two optical signals.

[0041] The external bias voltage includes a positive bias voltage and a negative bias voltage. The positive bias voltage and the negative bias voltage are used to control the positive polarization and negative polarization states of the device, thereby realizing different logic functions.

[0042] The negative feedback circuit includes a current amplifier and a current conversion circuit for converting pyroelectric current into a recognizable digital logic signal.

[0043] The preparation process of the present invention includes the following steps:

[0044] First, such as Figure 2 As shown, a layer of photoresist 1 is uniformly spin-coated onto a 1.5 × 1.5 mm no-wash silica substrate using a spin coater, followed by pre-baking using a heated stage to solidify the photoresist 1, ensuring the fidelity of subsequent pattern transfer. After UV maskless patterning exposure and development, as shown... Figure 3 As shown, a 20 nm bottom electrode 2 is deposited on the patterned photoresist using electron beam evaporation technology; after removing the residual photoresist on the substrate, a bottom electrode 2 is formed on the substrate as shown. Figure 4 The graphical bottom electrode 2 is shown.

[0045] Subsequently, the same photolithography process was used to fabricate the intermediate layer and top electrode of the device. The fabrication of the intermediate layer required transferring a sample with photoresist to the ALD chamber, using Hf[N(CH3)(C2H5)]4 and ZrC8N4H4. 24 As a precursor, Hf[N(CH3)(C2H5)]4 is tetra(ethylmethylamino)hafnium, ZrC8N4H 24 Specifically, tetrakis(dimethylamino)zirconia was used, with deionized water as the oxygen source, to deposit a HZO film of approximately 10 nm. The Hf to Zr cycling ratio was 1:1, and the deposition temperature was 100℃ (ultra-low temperature deposition technology), ultimately forming a film like... Figure 5 The structure shown includes a bottom electrode 2 and an intermediate layer 3.

[0046] Next, the bottom electrode operation was repeated to deposit a 20 nm top electrode 4 on the HZO film. Finally, rapid thermal annealing (RTP) was used to anneal at 550 °C for 150 seconds under a nitrogen atmosphere to obtain a W / HZO / W / SiO2 structure, as shown below. Figure 6 As shown.

[0047] like Figure 7 As shown, Figure 7The three waveforms from top to bottom represent the external bias voltage, the pyroelectric current and the laser, respectively. Under the irradiation of the 808 nm laser, the internal dipole oscillates with the change of the surface temperature, thereby generating a pyroelectric transient current response. By applying an external bias voltage, the pyroelectric current of the device can be effectively regulated. Under the same light irradiation conditions, the pyroelectric current in the HZO thin film changes with the change of the polarization direction. In addition, increasing the external bias voltage to increase the remanent polarization of the ferroelectric thin film can further improve the strength of the pyroelectric current. When the voltage is continuously applied, the pyroelectric current of the device is superimposed with the current generated by the bias voltage. Therefore, by adjusting the external bias voltage, the dynamic regulation of the light response characteristics of the device can be realized, which provides a physical basis for the device to realize the function of the reconfigurable logic gate.

[0048] The present application uses two near-infrared lasers as inputs of the optoelectronic logic gate, utilizes the regulatable and non-volatile characteristics of the polarization state of the ferroelectric thin film, and realizes the reconfigurable modulation of the output pyroelectric current of the logic gate. Figure 8 As shown in the figure, the on and off of the input light correspond to the logic values 1 and 0, respectively, and the baseline value of the output current is set to +28 nA·cm -2 , and the current is defined as logic 1 when it is higher than the baseline value, and as logic 0 when it is lower than the baseline value.

[0049] The peripheral circuit configuration of the present application is shown in the figure. Figure 9 The probes for applying bias are respectively placed on the pads extended by the bottom electrode, the pad of the top electrode is grounded, and a negative feedback circuit is externally connected to the output end at the same time, and the negative feedback circuit can convert the current into high and low level output.

[0050] The logic implementation of the present application is shown in the figure. Figure 10- Figure 14 When a positive bias pulse of +1.8V to +5V is applied, the device works in the positive polarization direction, and the AND gate and the OR gate both work in the positive polarization direction, that is, a positive pyroelectric current is generated at the moment of light irradiation;

[0051] If the bias is not continuously applied, the reconfigurable optoelectronic logic gate is an AND gate. For the AND gate, when the input logic is 00, 01 or 10, the pyroelectric current generated by the device is lower than the baseline current, and the output logic is 0; when the input logic is 11, the pyroelectric current generated by the device is higher than the baseline current, and the corresponding output logic is 1;

[0052] If a +300 mV bias is continuously applied to the current of the device to adjust the current to +7 nA·cm -2 , the reconfigurable optoelectronic logic gate is an OR gate. For the OR gate, when the input logic is 00, the pyroelectric current generated by the device is lower than the baseline current, and the output logic is 0; when the input logic is 01, 10 or 11, the pyroelectric current generated by the device is higher than the baseline current, and the corresponding output logic is 1.

[0053] When a negative bias pulse of-1.8V to-5V is applied, the device works in the negative polarization direction, and the NAND gate, NOR gate and NOT gate all work in the negative polarization direction, that is, a negative pyroelectric current is generated in the moment of light irradiation;

[0054] If a +400 mV bias is continuously applied to modulate the current of the device, the current is adjusted to +37nA·cm -2 , the reconfigurable optoelectronic logic gate can be a NOR gate. For the NOR gate, when the input logic is 00, the pyroelectric current generated by the device is higher than the baseline current, and the output logic is 1; when the input logic is 01, 10 or 11, the pyroelectric current generated by the device is lower than the baseline current, and the corresponding output logic is 0.

[0055] If a +450 mV bias is continuously applied to modulate the current of the device, the current is adjusted to +52nA·cm -2 , the reconfigurable optoelectronic logic gate can be a NOT gate. For the NOT gate, only two input states are involved, and a double light path synchronous switch is used for simulation. When the input logic is 00, the pyroelectric current generated by the device is higher than the baseline current, and the output logic is 1; when the input logic is 11, the pyroelectric current generated by the device is lower than the baseline current, and the corresponding output logic is 0.

[0056] If a +500 mV bias is continuously applied to modulate the current of the device, the current is adjusted to +61nA·cm -2 , the reconfigurable optoelectronic logic gate can be a NAND gate. For the NAND gate, when the input logic is 00, 01 or 10, the pyroelectric current generated by the device is higher than the baseline current, and the output logic is 1; when the input logic is 11, the pyroelectric current generated by the device is lower than the baseline current, and the corresponding output logic is 0.

Claims

1. A reconfigurable optoelectronic logic gate based on pyroelectric effect of hafnium-based ferroelectric thin films, characterized in that: The application relates to a device for realizing five kinds of logic gates, which comprises a substrate, two symmetrical devices arranged on the left and right sides of the substrate, a top electrode, an intermediate layer and a bottom electrode arranged in sequence from top to bottom, and a laser emitter arranged above the device, wherein the intermediate layer is made of a ferroelectric film; an external bias voltage is applied to the top electrode of the two devices, and the bottom electrodes of the two devices are grounded; under the irradiation of near-infrared laser, the surface temperature of the device changes, and then pyroelectric current is generated; the pyroelectric current is converted into high-level or low-level output after being processed by a negative feedback circuit; the polarization direction and the residual polarization strength of the ferroelectric film are controlled by adjusting the external bias voltage, so that the pyroelectric current response is adjusted, and the operation of five kinds of logic gates is realized, and the five kinds of logic gates include an AND gate, an OR gate, a NAND gate, a NOR gate and a NOT gate.

2. The reconfigurable optoelectronic logic gate based on hafnium-based ferroelectric thin film pyroelectric effect according to claim 1, wherein: The external bias voltage comprises a positive bias voltage and a negative bias voltage, and the positive bias voltage and the negative bias voltage are used for controlling the positive polarization and the negative polarization states of the device respectively, so that different logic functions are realized.

3. The reconfigurable optoelectronic logic gate based on hafnium-based ferroelectric thin film pyroelectric effect according to claim 2, wherein: When a positive bias voltage pulse of +1.8V to +5V is applied, the device works in the positive polarization direction, and the AND gate and the OR gate work in the positive polarization direction, that is, positive pyroelectric current is generated at the moment of irradiation; If the bias voltage is not continuously applied, the photoelectric logic gate can be reconstructed into an AND gate; for the AND gate, when the input logic is 00, 01 or 10, the pyroelectric current generated by the device is lower than the baseline current, and the output logic is 0; when the input logic is 11, the pyroelectric current generated by the device is higher than the baseline current, and the corresponding output logic is 1; If the current of the device is modulated by continuously applying a +300 mV bias, the current is adjusted to +7 nA-cm -2 The reconfigurable photoelectric logic gate can be an OR gate. When the input logic is 00, the pyroelectric current generated by the device is lower than the baseline current, and the output logic is 0. When the input logic is 01, 10 or 11, the pyroelectric current generated by the device is higher than the baseline current, and the corresponding output logic is 1.

4. The reconfigurable optoelectronic logic gate based on hafnium-based ferroelectric thin film pyroelectric effect according to claim 3, wherein: When a negative bias voltage pulse of -1.8V to -5V is applied, the device works in the negative polarization direction, and the NAND gate, the NOR gate and the NOT gate work in the negative polarization direction, that is, negative pyroelectric current is generated at the moment of irradiation; If the current of the device is modulated by continuously applying a +400 mV bias, the current is adjusted to +37 nA-cm -2 The reconfigurable photoelectric logic gate can be a NOR gate. When the input logic is 00, the pyroelectric current generated by the device is higher than the baseline current, and the output logic is 1. When the input logic is 01, 10 or 11, the pyroelectric current generated by the device is lower than the baseline current, and the output logic is 0. If the current of the device is modulated by continuously applying a +450 mV bias, the current is adjusted to +52 nA-cm -2 The reconfigurable optoelectronic logic gate can be a NOT gate. For the NOT gate, only two input states are involved, and a dual-optical-path synchronous switch is simulated. When the input logic is 00, the pyroelectric current generated by the device is higher than the baseline current, and the output logic is 1. When the input logic is 11, the pyroelectric current generated by the device is lower than the baseline current, and the output logic is 0. If the current of the device is modulated by continuously applying a +500 mV bias, the current is adjusted to +61 nA·cm -2 The reconfigurable photoelectric logic gate can be a NAND gate. When the input logic is 00, 01 or 10, the pyroelectric current generated by the device is higher than the baseline current, and the output logic is 1. When the input logic is 11, the pyroelectric current generated by the device is lower than the baseline current, and the output logic is 0.

5. The reconfigurable optoelectronic logic gate based on hafnium-based ferroelectric thin film pyroelectric effect according to claim 1, wherein: The intermediate layer material is hafnium-zirconium oxide, and the top electrode and the bottom electrode material are one of titanium nitride, gold, platinum or tungsten. 6.The reconfigurable photologic gate based on hafnium-based ferroelectric thin film pyroelectric effect of claim 1, wherein: The input light signal of the device is two-way near-infrared laser, wherein the light input in the on state represents logic 1, and the light input in the off state represents logic 0; the on-off state of the two-way light signal is adjusted to realize the function of a double-input logic gate.

7. The reconfigurable optoelectronic logic gate based on hafnium-based ferroelectric thin film pyroelectric effect according to claim 1, wherein: The ferroelectric film is a hafnium-zirconium oxide film, which is deposited at 100 DEG C through an atomic layer deposition (ALD) process, so as to ensure the compatibility with the CMOS process.

8. The reconfigurable optoelectronic logic gate based on hafnium-based ferroelectric thin film pyroelectric effect according to claim 7, wherein: The deposition thickness of the ferroelectric film is 10nm to 20nm, and the ferroelectric film is annealed through a rapid thermal processing (RTP) process in a nitrogen atmosphere. 9.The reconfigurable photologic gate based on hafnium-based ferroelectric thin film pyroelectric effect of claim 1, wherein: The negative feedback circuit comprises a current amplifier and a current conversion circuit, and is used for converting the pyroelectric current into identifiable digital logic signals.

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