Si-based pn tunnel junction multi-mode piezoelectric sensor and design and characterization method thereof

Abstract

The invention discloses a Si-based pn tunnel junction multi-mode piezoelectric sensor and a design and characterization method thereof, and the sensor comprises an n-type doped layer which takes a silicon substrate as a base material; the p-type doped layer takes the silicon substrate as a base material, and the p-type doped layer is arranged on the upper side or the lower side of the n-type doped layer and is in close contact with the n-type doped layer; the thickness of the n-type doped layer and the thickness of the p-type doped layer are both 18-22 nm. The doping concentration is 3 * 10 < 19 > cm <-3 > to 9 * 10 < 19 > cm <-3 >; and an Al electrode. According to the embodiment of the invention, symmetrical breaking is realized by inducing an internal electric field, so that strain sensing is realized in a centrosymmetric silicon-based device, and the strain sensitivity is continuously adjustable; symmetrical breaking induction piezoelectric effect and quantum tunneling effect are combined, strain modulation piezoelectric polarization charge and bias voltage regulation tunneling probability are utilized to synergistically generate amplification effect, and sensitivity is improved by more than 8 times compared with that of a traditional silicon-based piezoresistive sensor.

Description

TECHNICAL FIELD

[0001] The embodiment of the present disclosure relates to the technical field of semiconductor sensors, in particular to a Si-based pn tunnel junction multi-modal piezoelectric sensor and a design and characterization method thereof. BACKGROUND

[0002] High-performance electromechanical sensing technology can convert weak mechanical stimuli into electrical signals, and is the core component in application fields such as human-computer interaction, wearable electronics, intelligent systems and sensors. Among them, multi-modal piezoelectric electronic sensor stands out due to its adjustable strain sensitivity characteristics. It only needs to adjust the bias voltage to realize the switching of the sensing mode, and at the same time has excellent electromechanical coupling performance. Its core mechanism is based on the piezoelectric electronic effect, that is, the piezoelectric potential induced by pressure or strain is used to control the semiconductor interface barrier, thereby controlling the carrier transport. The synergistic effect of this effect with other physical mechanisms has given rise to many breakthrough applications, such as ultra-high sensitivity strain sensors, dual-mode transistors and other innovative devices.

[0003] Piezoelectric electronics is the basic mechanism of many piezoelectric sensors. For most non-centrosymmetric semiconductors (such as zinc blende structure GaAs and AlAs), although they naturally have piezoelectricity, it is difficult to excite the piezoelectric effect through shear or bending strain, so their application in piezoelectric electronics is limited. The current mainstream piezoelectric materials (such as wurtzite structure ZnO and GaN) also have obvious defects: their piezoelectric strength is only comparable to that of dielectric insulators or narrow-bandgap semiconductors, and there is a large lattice mismatch with hetero-materials, resulting in a decrease in device performance. In addition, the strain sensitivity of traditional piezoelectric devices is fixed and cannot be adjusted, and the application mode is relatively single, which cannot meet the needs of complex application scenarios. Therefore, it is urgent to develop new piezoelectric electronic material systems with adjustable sensitivity, especially multi-modal sensors based on mature semiconductor materials (such as centrosymmetric structure Si and Ge).

[0004] For semiconductors with centrosymmetric structure, due to the limitation of lattice symmetry, they usually cannot exhibit intrinsic piezoelectric effect. However, the symmetry constraint of the material can be broken by built-in or external electric field, thereby artificially inducing piezoelectric response in the centrosymmetric system. The physical mechanism of this phenomenon is derived from the electrostriction effect of the material (strain is proportional to the square of the electric field strength). Studies have shown that Gd-doped The thin film can generate an effective piezoelectric coefficient of up to 50 pm / V under direct current bias. Compared with traditional piezoelectric materials, the breakthrough advantage of this system is that its piezoelectric performance can be dynamically regulated in real time by external electric field. It is worth noting that there are significant differences in the electric field threshold for different material systems to achieve effective piezoelectric response. For example, the piezoelectric response of single crystal silicon requires an electric field of up to 10 8Strong electric field in the order of V / m, which not only leads to significant energy consumption problems, but also may cause dielectric breakdown and other reliability challenges.

[0005] In addition to the externally applied electric field, the intrinsic electric field in the material (such as the Schottky junction space charge region) can also induce a piezoelectric response through symmetry breaking. Experimental studies have shown that Au / Nb:SrTiO3 and Au / Nb:BSTO heterojunctions exhibit significant piezoelectric coefficients of -4.07 pm / V and -12 pm / V, respectively, which is due to the synergistic effect of interface band bending and oxygen vacancy regulation. However, the complex oxide epitaxial growth process results in low device yield and high cost; while Au / Si Schottky junctions have mature semiconductor process compatibility, their piezoelectric coefficient is only -0.013 pm / V, which is difficult to meet the demand of micro-strain sensing.

[0006] In addition, although symmetry breaking has made important progress in basic research, its application in high-performance and multi-modal sensing remains to be explored.

[0007] Therefore, it is necessary to improve one or more problems existing in the above related technical solutions.

[0008] It should be noted that this section aims to provide background or context for the technical solutions of the disclosure stated in the claims. The description herein is not admitted to be prior art merely because it is included in this section. SUMMARY

[0009] The purpose of the embodiments of the present disclosure is to provide a Si-based pn tunnel junction multi-modal piezoelectric sensor and its design and characterization method, thereby at least to some extent overcoming one or more problems caused by the limitations and defects of the related art.

[0010] In a first aspect, the embodiments of the present disclosure provide a Si-based pn tunnel junction multi-modal piezoelectric sensor, comprising: An n-type doped layer, the n-type doped layer taking a silicon substrate as a base material, the thickness of the n-type doped layer being 18-22 nm, the doping element of the n-type doped layer being at least one of P, As and Sb, and the doping concentration being 3×10 19 cm -3 ~9×10 19 cm -3 ; A p-type doped layer, the p-type doped layer taking a silicon substrate as a base material, the p-type doped layer being arranged on the upper side or lower side of the n-type doped layer and being in close contact, the thickness of the p-type doped layer being 18-22 nm; the doping element of the p-type doped layer being at least one of B, Al and Ga, and the doping concentration being 3×10 19 cm -3 ~9×10 19cm -3 ; electrodes, the electrodes are Al electrodes, and the outer sides of the n-type doped layer and the p-type doped layer are provided with Al electrodes.

[0011] In an embodiment of the present disclosure, the doping concentrations of the n-type doped layer and the p-type doped layer have a preset difference or are equal, and when there is a preset difference, the difference between the peak concentrations of the two is controlled within ±5%.

[0012] In an embodiment of the present disclosure, the doping concentrations of the n-type doped layer and the p-type doped layer form peak concentrations at the junction of the two layers, and when extending from the junction to the outer side of the n-type doped layer, the doping concentration has an exponential decay trend, and the decay coefficient is 0.05-0.1 nm -1 ; when extending from the junction to the outer side of the p-type doped layer, the doping concentration also has an exponential decay trend, and the decay coefficient is 0.05-0.1 nm -1 .

[0013] In a second aspect of the embodiment of the present disclosure, a design method of a Si-based pn tunnel junction multi-modal piezoelectric sensor is provided, comprising: Taking a high-purity silicon material as a substrate, impurity atoms are doped on the substrate through ion implantation or diffusion process to form an n-type doped layer and a p-type doped layer, respectively; The implanted impurity atoms are activated through an annealing process, and the lattice damage caused in the ion implantation process is repaired to form a pn tunnel junction at the junction of the n-type doped layer and the p-type doped layer; Al electrodes are deposited on the outer surfaces of the n-type doped layer and the p-type doped layer.

[0014] In a third aspect of the embodiment of the present disclosure, a characterization method of a Si-based pn tunnel junction multi-modal piezoelectric sensor is provided, comprising: Characteristic characterization and working interval definition: A scanning bias voltage (0 V-100 mV) is applied to the sensor of any one of the above embodiments V ds ), the Al electrode on the outer side of the p-type doped layer is connected to the positive electrode of the power supply, and the Al electrode on the outer side of the n-type doped layer is connected to the negative electrode of the power supply. The current-voltage characteristic is measured, and the inherent working interval of the sensor is defined according to the current-voltage characteristic curve, and the inherent working interval includes a negative differential resistance region and a hot electron emission region; Multi-modal strain detection: A controllable strain of -3% to +3% is applied to the sensor along a specific crystal direction of the crystal; High-sensitivity mode operation: The voltage located in the negative differential resistance region and corresponding to the end of the negative differential resistance region is selected as the first bias voltage, the current under different strains is measured, and the strain sensitivity under different strains is calculated. Low sensitivity mode operation: The voltage located in the thermal electron emission region and corresponding to the start of the thermal electron emission region is selected as the second bias voltage, the current under different strains is measured, and the strain sensitivity under different strains is calculated.

[0015] In an embodiment of the present disclosure, the characterization method further comprises: Multi-modal function verification: dynamically switching between the first bias voltage and the second bias voltage, and calculating the change of the sensitivity.

[0016] In an embodiment of the present disclosure, the first bias voltage is 50 mV, and the second bias voltage is 70 mV.

[0017] In a fourth aspect of the embodiments of the present disclosure, a use method of the Si-based pn tunnel junction multi-modal piezoelectric sensor is provided, and the sensor according to any one of the above embodiments is used to measure strain, comprising: according to the strain detection requirement of the actual application scene, selecting the first bias voltage or the second bias voltage to be applied to the sensor, and measuring the current change of the sensor under different strains to realize the measurement of the strain.

[0018] The technical solutions provided by the embodiments of the present disclosure can include the following beneficial effects: The Si-based pn tunnel junction multi-modal piezoelectric sensor in the embodiments of the present disclosure can realize strain sensing in a center-symmetric silicon-based device by inducing symmetry breaking, and the strain sensitivity is continuously adjustable; the symmetry breaking induced piezoelectric effect is combined with the quantum tunneling effect, the amplification effect is generated by cooperatively using the strain modulated piezoelectric polarization charge and the bias voltage controlled tunneling probability, so that the sensitivity is improved by more than 8 times compared with the traditional silicon-based piezoresistive sensor; intelligent switching of the two characteristic working modes can be realized by bias voltage control; only the doping concentration and bias voltage parameters need to be adjusted, without special materials or complex processes, and the compatibility with the existing mature semiconductor manufacturing process is good, which is conducive to reducing production cost and improving device yield. BRIEF DESCRIPTION OF DRAWINGS

[0019] The drawings incorporated into the specification and forming a part thereof, illustrate embodiments consistent with the present disclosure and, together with the specification, serve to explain the principles of the present disclosure. Obviously, the drawings in the following description are only some embodiments of the present disclosure, and other drawings can be obtained by those skilled in the art without creative labor on the basis of these drawings.

[0020] Figure 1This diagram illustrates the structure of a Si-based pn tunnel junction multimode piezoelectric sensor in an exemplary embodiment of this disclosure. Figure 2 This diagram illustrates a design method for a Si-based pn tunnel junction multimodal piezoelectric sensor according to an exemplary embodiment of this disclosure. Figure 3 A flowchart illustrating the characterization method of a Si-based pn tunnel junction multimodal piezoelectric sensor in an exemplary embodiment of this disclosure is shown. Figure 4 This diagram illustrates the band structure of a pn tunnel junction under interband tunneling and hot electron emission states in an exemplary embodiment of the present disclosure. Figure 5 This illustrates the bias effect under exemplary embodiments of the present disclosure. J - V Characteristic curves; Figure 6 This illustrates strain control within the inter-band tunneling section in an exemplary embodiment of this disclosure. J - V curve; Figure 7 This illustrates strain modulation within the thermionic emission range in an exemplary embodiment of this disclosure. J - V curve; Figure 8 This illustrates the variation of current with strain under different bias voltages in an exemplary embodiment of this disclosure. J - ɛ curve; Figure 9 This illustrates the GF-type strain sensitivity as a function of strain under different bias voltages in an exemplary embodiment of this disclosure. ɛ curve; Figure 10 Different doping concentrations are shown in exemplary embodiments of this disclosure. N d,a The optimized effect of strain sensitivity coefficient is shown in the figure. Detailed Implementation

[0021] Exemplary embodiments will now be described more fully with reference to the accompanying drawings. However, these exemplary embodiments can be implemented in many forms and should not be construed as limited to the examples set forth herein; rather, they are provided so that this disclosure will be more comprehensive and complete, and will fully convey the concept of the exemplary embodiments to those skilled in the art. The described features, structures, or characteristics may be combined in any suitable manner in one or more embodiments.

[0022] In addition, the accompanying drawings are only schematic and are not necessarily drawn to scale. The same reference numerals in different drawings denote the same or similar functionality throughout the various figures. The drawings record some block diagrams as functional entities, which do not necessarily have to correspond to physically or logically independent entities.

[0023] In the present example embodiment, a Si-based pn tunnel junction multimodal piezoelectric sensor is first provided, as shown in Figure 1 , which comprises an n-type doped layer, a p-type doped layer and an electrode.

[0024] Specifically, the n-type doped layer takes silicon substrate as base material, the thickness of the n-type doped layer is 18-22 nm, the doping element of the n-type doped layer is at least one of P, As and Sb, and the doping concentration is 3×10 19 cm -3 ~9×10 19 cm -3 .

[0025] The p-type doped layer takes silicon substrate as base material, and is arranged on the upper side or lower side of the n-type doped layer and in close contact, the thickness of the p-type doped layer is 18-22 nm; the doping element of the p-type doped layer is at least one of B, Al and Ga, and the doping concentration is 3×10 19 cm -3 ~9×10 19 cm -3 .

[0026] The peak doping concentration of the n-type doped layer and the p-type doped layer has a preset difference or is equal, and when there is a preset difference, the difference of the peak concentration should be controlled within ±5%.

[0027] In addition, the doping concentration of the n-type doped layer and the p-type doped layer is the highest at the interface between the two layers, and the doping concentration of the two layers decreases exponentially with the distance from the interface, and the attenuation coefficient should be 0.05-0.1 nm -1 when extending from the interface to the outside of the n-type doped layer, and the attenuation coefficient should be 0.05-0.1 nm -1 when extending from the interface to the outside of the p-type doped layer. Preferably, as shown in Figure 10 , the doping concentration of the two doped layers can be selected as 3×10 19 cm -3 , at which the strain sensitivity is the highest.

[0028] The n-type doped layer and the p-type doped layer are both provided with the electrode on the outer side. The electrode adopts Al electrode, which is prepared by electron beam evaporation, sputtering and other processes, and forms ohmic contact to ensure good electrical signal transmission.

[0029] The piezoelectric sensor in the application can achieve symmetry breaking by inducing an internal electric field to achieve strain sensing in a center-symmetric silicon-based device, and the strain sensitivity is continuously adjustable, with a dynamic range of 15.6 times (GF continuously adjustable from 50 to 780). Intelligent switching between the ultra-high sensitivity mode and the low sensitivity mode can be achieved by simple bias switching, breaking through the "one device one sensitivity" and the fixed limitation of material symmetry of traditional sensors, and providing a flexible solution for adaptive sensing under complex working conditions. The application innovatively combines symmetry breaking induced piezoelectric effect with quantum tunneling effect, and uses strain modulated piezoelectric polarization charge and bias controlled tunneling probability to cooperatively generate amplification, so that the sensitivity is increased by more than 8 times compared with traditional silicon-based piezoresistive sensors. The piezoelectric sensor of the application can achieve intelligent switching of two characteristic working modes through bias control: the negative differential resistance region (0 V ds ≤ 50 mV) provides ultra-high sensitivity (GF up to 780), meeting the needs of conventional strain measurement; and the thermionic emission region ( V ds >70 mV) provides wide dynamic range detection (GF<50), ensuring stable operation under large strain conditions. This multi-mode design makes a single device adaptable to different application scenarios from precision medical monitoring to industrial vibration detection; The piezoelectric sensor of the application is based on a standard silicon-based pn junction structure, and only needs to adjust the doping concentration and bias parameters, without the need for special materials or complex processes; the doping concentration belongs to heavy doping. The device performance can be optimized in multiple dimensions such as doping and bias voltage, and has excellent engineering application prospects.

[0030] The application provides a design method of a Si-based pn tunnel junction multi-modal piezoelectric sensor, which is used to design the silicon-based sensor in any one of the above embodiments, as shown in Figure 2 The design method comprises the following steps: S101, using high-purity silicon material (purity ≥ 99.999%) as a substrate, doping impurity atoms on the substrate by ion implantation or diffusion process to form n-type doped layer and p-type doped layer.

[0031] S102, activating the implanted impurity atoms by annealing process (annealing temperature 800~1000℃), and repairing the lattice damage caused in the ion implantation process to form a pn tunnel junction at the junction of the n-type doped layer and the p-type doped layer. The pn tunnel junction has high quality and strong built-in electric field.

[0032] S103, depositing metal electrodes on the outer surface of the n-type doped layer and the p-type doped layer. For example, metal Al can be deposited by using a standard metal deposition process (such as electron beam evaporation), thereby forming an ohmic contact electrode for applying a bias voltage and reading a signal.

[0033] The Si-based pn tunnel junction multimodal piezoelectric sensor in the present application has a simple preparation process, low cost, and good compatibility with existing semiconductor processes.

[0034] Further, the built-in electric field strength can be changed by adjusting the doping concentration gradient (such as adjusting the ion implantation dose or diffusion time), and the sensitivity of the device can be optimized.

[0035] Next, the characterization method of the sensor in the present application is described, as shown in Figure 3 The characterization method includes: S201, characteristic characterization and working interval definition: A scanning bias voltage from 0 V to 100 mV is applied to the sensor, the Al electrode on the outer side of the p-type doped layer is connected to the positive electrode of the power supply, and the Al electrode on the outer side of the n-type doped layer is connected to the negative electrode of the power supply. The current-voltage characteristic (I-V characteristic) is measured I - V ), and the inherent working interval of the sensor is defined according to I - V characteristic curve, the inherent working interval of the sensor includes a negative differential resistance region and a hot electron emission region.

[0036] As can be seen from Figure 5 , (1) the negative differential resistance (NDR) region: under a low forward bias voltage of about 0-60 mV, the current increases first and then decreases with the increase of the voltage. The carrier transport in this interval is mainly interband tunneling, the physical mechanism of which is shown in Figure 4 (a), under a forward bias voltage, the conduction band of the n region and the valence band of the p region overlap to form a tunneling window. (2) The hot electron emission region: under a higher forward bias voltage of about >60 mV, the tunneling window is closed, and the physical mechanism is shown in Figure 4 (b), the carrier transport mechanism changes to be mainly hot electron emission, and the current increases with the voltage.

[0037] S202, multimodal strain detection: A controllable strain of -3% to +3% can be applied to the sensor along a specific crystal direction of the crystal, and a precise mechanical stretching platform can be used to apply strain to the sensor.

[0038] S203, high sensitivity mode operation: The voltage in the negative differential resistance region is selected as the first bias voltage, the current under different strains is measured, and the strain sensitivity under different strains is calculated.

[0039] Specifically, to detect the micro-strain, a voltage in the NDR region is selected as the first bias voltage, which is preferably 50 mV in the embodiment. As shown in the figure, under this bias voltage, the micro-strain change can cause an exponential response of the current. In addition, the strain sensitivity GF under different strains is calculated by Figure 6 GF J ε J ε J ε ε Figure 8 The current-strain (I-S) curve under the 50 mV bias voltage shows a significant exponential change characteristic, and the GF value calculated based on the data, as shown in the figure, indicates that the strain coefficient under this bias voltage can reach 780, which is the highest among all the tested bias voltages. This result confirms that the NDR region bias can effectively amplify the micro-strain signal. J ɛ Figure 9

[0040] S204, low sensitivity mode operation:A voltage in the thermionic emission region is selected as the second bias voltage, and the current under different strains is measured to calculate the strain sensitivity under different strains.

[0041] Specifically, to detect the micro-strain, a voltage in the NDR region is selected as the first bias voltage, which is preferably 50 mV in the embodiment. As shown in the figure, under this bias voltage, the micro-strain change can cause an exponential response of the current. In addition, the strain sensitivity GF under different strains is calculated by Figure 7

[0042] From the quantitative analysis of Figure 8 and Figure 9 , it can be seen that under the 70 mV bias, GF is stably maintained below 50, which is significantly different from the high sensitivity mode (GF = 780). This characteristic confirms that the thermionic emission region is particularly suitable for wide-range strain detection.

[0043] S205, multi-mode function verification: dynamically switch between the first bias voltage and the second bias voltage, and calculate the sensitivity change. Through the external control circuit, dynamic switching between the 50 mV and 70 mV bias voltages is performed. Experimental verification shows that the sensor can seamlessly switch between the two modes, with a high-to-low sensitivity switching ratio of up to 610, proving its strong multi-scenario adaptive sensing ability.

[0044] ​​​​​​​​​​​​​The piezoelectric sensor of the application can be used to measure strain.

[0045] The application breaks the central symmetry of the material crystal by constructing a heavily doped Si-based pn junction and using the strong built-in electric field to induce equivalent piezoelectricity based on the electrostrictive effect, thereby solving the problem of no intrinsic piezoelectricity of traditional Si materials.

[0046] The application innovatively combines the piezoelectric effect induced by symmetry breaking with the quantum tunneling effect, directly changes the width of the tunneling barrier by the piezoelectric polarization charge regulated by strain, and controls the adjustable range of the barrier width and the transport mode of the carriers (low bias: interband tunneling, high voltage: hot electron emission) by the bias voltage, and the two synergistically control the transport of the carriers.

[0047] The application innovatively combines the piezoelectric effect with the quantum tunneling effect, and the two synergistically generate an amplification mechanism to improve the strain sensing performance. Specifically, the mechanical strain modulates the width of the depletion region through the piezoelectric effect, and the quantum tunneling current presents an exponential dependence on the change in the barrier width. This “piezoelectric modulation-tunneling amplification” cascade mechanism enables weak strain to cause significant changes in conductance, thereby achieving a strain sensitivity (GF) of up to 780, which is nearly an order of magnitude higher than the sensitivity of traditional silicon-based piezoresistive sensors.

[0048] The application adopts a synergistic optimization strategy of “wide depletion region + tunneling bias”, and optimizes the doping concentration (such as using relatively low heavy doping (3×10 19 cm -3 ) or using symmetric doping (the doping concentration of the n region and the p region is close or equivalent)) to moderately adjust the depletion region to increase the regulation ability of strain, and sets the high sensitivity working point in the negative differential resistance region which is most sensitive to the barrier, thereby optimizing the overall performance of the device.

[0049] The application can realize multiple sensitivity outputs with a single device. By utilizing the difference in carrier transport mechanisms (interband tunneling vs. hot electron emission) of the device under different bias voltages (low forward bias vs. higher forward bias), combined with simple external voltage regulation, the device can be continuously switched between the ultra-high sensitivity mode and the low sensitivity stability mode, realizing multi-modal detection.

[0050] The embodiments of the application are described above in combination with the drawings, but the application is not limited to the above specific embodiments, and the above specific embodiments are only illustrative and not limiting. Those skilled in the art can make many forms under the inspiration of the application without departing from the purpose of the application and the scope protected by the claims, and these all belong to the protection of the application.

Claims

1. A Si-based pn tunnel junction multi-modal piezoelectric sensor, characterized by, The sensor comprises: n-type doped layer, the n-type doped layer has a thickness of 18-22 nm, a doping element of at least one of P, As and Sb, and a doping concentration of 3x10 19 cm -3 ~9x10 19 cm -3 ; A p-type doped layer with a silicon substrate as a base material, which is arranged on the upper side or lower side of the n-type doped layer and in close contact, and the thickness of the p-type doped layer is 18-22 nm; the doping element of the p-type doped layer is at least one of B, Al and Ga, and the doping concentration is 3x10 19 cm -3 ~9x10 19 cm -3 ; An electrode, which is an Al electrode, provided on the outer side of the n-type doped layer and the p-type doped layer.

2. The Si-based pn junction multi-modal piezoelectric sensor of claim 1, wherein, The doping concentration of the n-type doped layer and the p-type doped layer has a preset difference or is equal, wherein when the preset difference exists, the peak concentration difference of the two is controlled within ±5%.

3. The Si-based pn tunnel junction multi-modal piezoelectric sensor of claim 1, wherein, The doping concentration of the n-type doped layer and the p-type doped layer forms a peak concentration at the junction of the two layers, and the doping concentration exponentially decays with a decay coefficient of 0.05-0.1 nm when extending from the junction to the outside of the n-type doped layer -1 ; the doping concentration also exponentially decays with a decay coefficient of 0.05-0.1 nm when extending from the junction to the outside of the p-type doped layer -1 .

4. A method of designing a Si-based pn tunnel junction multi-modal piezoelectric sensor, characterized by, The sensor of any one of claims 1-3 is designed by a method comprising: A high-purity silicon material is used as a substrate, and impurity atoms are doped on the substrate by ion implantation or diffusion process to form an n-type doped layer and a p-type doped layer, respectively; The implanted impurity atoms are activated by an annealing process, and the lattice damage caused by the ion implantation process is repaired to form a pn tunnel junction at the junction of the n-type doped layer and the p-type doped layer; An Al electrode is deposited on the outer side surface of the n-type doped layer and the p-type doped layer.

5. A method of characterizing a Si-based pn tunnel junction multimodal piezoelectric sensor, the method comprising: The sensor of any one of claims 1-3 is characterized and the working range is defined by a method comprising: A scanning bias voltage from 0 V to 100 mV is applied to the sensor, the Al electrode on the outer side of the p-type doped layer is connected to the positive electrode of the power supply, and the Al electrode on the outer side of the n-type doped layer is connected to the negative electrode of the power supply, the current-voltage characteristic of the sensor is measured, and the inherent working range of the sensor is defined according to the current-voltage characteristic curve, wherein the inherent working range includes a negative differential resistance region and a hot electron emission region; Multi-modal strain detection: A controllable strain of -3% to +3% is applied to the sensor along a specific crystal direction of the crystal; High sensitivity mode operation: A voltage located in the negative differential resistance region is selected as a first bias voltage, the current of the sensor under different strains is measured respectively, and the strain sensitivity under different strains is calculated according to the measured current; Low sensitivity mode operation: A voltage located in the hot electron emission region is selected as a second bias voltage, the current of the sensor under different strains is measured respectively, and the strain sensitivity under different strains is calculated according to the measured current. The characterization method further comprises:

6. The method of characterizing a Si-based pn tunnel junction multimodal piezoelectric sensor of claim 5, wherein, Multi-modal function verification: dynamically switching between the first bias voltage and the second bias voltage, and calculating the sensitivity change. The first bias voltage is 50 mV, and the second bias voltage is 70 mV.

7. The method of characterizing a Si-based pn tunnel junction multimodal piezoelectric sensor according to claim 6, wherein, The sensor of any one of claims 1-3 is used to measure strain.

8. A method of using a Si-based pn tunnel junction multimodal piezoelectric sensor, characterized by, ​

Images