A rectifier diode based on C3Al heterojunction and its design method

Abstract

The invention discloses a rectifier diode based on a C3Al heterojunction and a design method thereof, belonging to the field of nanoelectronic technology; a design method for a rectifier diode based on a C3Al heterojunction comprises: cutting a C3Al nanoribbon into three edge forms; calculating an energy band structure diagram for the C3Al nanoribbons with the three edge forms; using the C3Al nanoribbons with the three edge forms to respectively build heterojunction devices; calculating current values ​​of the heterojunction devices at different voltages; designing a rectifier diode using the current value of the device; negative differential resistance effect and rectification phenomenon occur in heterojunction devices built based on C3Al nanoribbons with different edges, which greatly enriches the application of the C3Al nanoribbon in the field of electronic devices.

Description

Technical Field

[0001] The invention belongs to the field of nanoelectronic technology, and in particular relates to a rectifier diode based on a C3Al heterojunction and a design method thereof. Background Art

[0002] Since the discovery of graphene, the research field of two-dimensional (2D) materials has developed rapidly. 2D materials have excellent mechanical, thermal and electrical properties and have great potential in various applications such as sensors and electronic devices. Various interesting electronic transport properties have been found in nanodevices based on 2D materials, such as negative differential resistance, rectification, spin filtering, switching, and field effect transistors.

[0003] C3Al has a similar structure to graphene and achieved a thermodynamically stable configuration in 2022, but C3Al devices have not been further studied. Summary of the invention

[0004] In view of the deficiencies in the prior art, the purpose of the present invention is to provide a rectifier diode based on a C3Al heterojunction and a design method thereof, which solves the problems in the prior art.

[0005] The purpose of the present invention can be achieved by the following technical solutions:

[0006] A design method for a rectifier diode based on a C3Al heterojunction comprises the following steps:

[0007] The C3Al nanoribbons were cut into three edge morphologies;

[0008] The energy band structure diagrams are calculated for the three edge morphologies of C3Al nanoribbons;

[0009] Using the three edge morphologies of C3Al nanoribbons to build heterojunction devices respectively;

[0010] Calculating the current value of the heterojunction device at different voltages;

[0011] The rectifier diode is designed based on the current effect exhibited by the device current value.

[0012] Furthermore, in C3Al, the bond lengths of the CC bond and the Al-C bond are and

[0013] Furthermore, the three edge forms are:

[0014] (1) There are Al atoms on both edges, denoted as XAlAl;

[0015] (2) One edge has no Al atoms and the other has Al atoms, denoted as XCAl;

[0016] (3) The edges are all C atoms, denoted as XCC;

[0017] where X is the number of atoms across the width of the nanoribbon.

[0018] Furthermore, according to the energy band structure diagram and C3Al nanobelt structure analysis, C3Al nanobelts with different edge morphologies undergo a transition from metal to semiconductor.

[0019] Furthermore, the left side of the constructed heterojunction device is a 3CAl nanobelt, and the right side is three edge morphologies of the C3Al nanobelt. The heterojunction device includes the following three types: 3CAl-XCC, 3CAl-XCAl and 3CAl-XAlAl.

[0020] Furthermore, the calculation formula of the current value of the heterojunction device is:

[0021] When calculating the current value of a heterojunction device at different voltages, the current value is calculated according to the Landauer-Büuttiker multi-terminal multi-channel formula:

[0022]

[0023] Where I(V) is the current value of the system, e is the electron charge, h is Planck's constant, and E is the energy value; μ L and μ R are the chemical potentials of the left and right electrodes, respectively, f(E-μ L ) and f(E-μ R ) are the Fermi distributions of the left and right electrodes, respectively, and V=(μ L -μ R ) / e represents the bias window; T(E,V) is the spin-dependent transmission coefficient.

[0024] Furthermore, the calculation formula of T(E,V) is:

[0025] T(E,V)=Tr[Γ L (E,V)G R (E,V)Γ R (e,V)G A (e,V)]

[0026] Among them, G R (E,V) and G A (E, V) are the delayed and advanced Green's functions in the scattering region, respectively, and Γ L and Γ R are the coupling matrices of the left (right) electrodes respectively.

[0027] A rectifier diode is designed using the above-mentioned design method for a rectifier diode based on a C3Al heterojunction.

[0028] A method for constructing a heterojunction device comprises the following steps:

[0029] The C3Al nanoribbons were cut into three edge morphologies;

[0030] The energy band structure diagrams are calculated for the three edge morphologies of C3Al nanoribbons;

[0031] Heterojunction devices were constructed using the three types of C3Al nanoribbons with edge morphologies.

[0032] A heterojunction device is constructed using the above-mentioned heterojunction device construction method.

[0033] The above heterojunction devices are used in building rectifier diodes.

[0034] Beneficial effects of the present invention:

[0035] 1. C3Al nanoribbons with different edges exhibit different electronic properties. XCC and XCAl are metals, and XAlAl is a semiconductor.

[0036] 2. Heterojunction devices constructed according to different electronic properties exhibit different current effects. In heterojunction devices constructed of metal and metal, namely 3CAl-XCC and 3CAl-XCAl devices, negative differential resistance effect appears, and in heterojunction devices constructed of metal and semiconductor, namely 3CAl-XAlAl devices, rectifier diode effect is exhibited.

[0037] 3. Enriched the application of C3Al nanoribbons in the field of electronic devices. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0039] Figure 1 It is C3Al structure;

[0040] Figure 2 Schematic diagram of the structures of 6CC, 5CAl and 4AlAl ZC3AlNR;

[0041] Figure 3 It is the band structure and the contour surface of the Γ-point wave function of the sub-band near the Fermi level;

[0042] Figure 4Schematic diagram of the C3Al-HJ device structure;

[0043] Figure 5 is the current-voltage curve of the device in the bias range of -1.0 to 1.0 V;

[0044] Figure 6 is the transmission spectrum of the device at 0.2V, 0.4V and 0.6V bias;

[0045] Figure 7 is the transmission eigenstate of XCAl ZC3AlNRs;

[0046] Figure 8 The band structures of nanoribbons of different widths near the Fermi level. DETAILED DESCRIPTION

[0047] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0048] Example 1

[0049] like Figure 1 As shown, a design method of a rectifier diode based on a C3Al heterojunction comprises the following steps:

[0050] S1, C3Al nanobelts are cut into three edge morphologies;

[0051] like Figure 1 As shown, a C3Al model was constructed in this embodiment and its structural stability was demonstrated; the bond lengths of the CC bond and the Al-C bond are and Due to the heterogeneity of C and Al elements, C3Al nanoribbons are cut according to different jagged edge morphologies. There are three edge morphologies:

[0052] (1) There are Al atoms on both edges, named XAlAl;

[0053] (2) One edge has no Al atoms and the other has Al atoms, named XCAl;

[0054] (3) There are C atoms on both edges, named XCC;

[0055] where X is the number of atoms across the width of the nanoribbon.

[0056] S2, the band structure diagram of C3Al nanoribbons with different edge morphologies is calculated. According to the band structure diagram and the structural analysis of C3Al nanoribbons, the C3Al nanoribbons with different edge morphologies undergo a transition from metal to semiconductor.

[0057] Among the nanoribbons with three edge morphologies, 4AlAl, 5CAl and 6CC are selected as representatives to analyze their electronic structures. Figure 2 As shown. Comparing these three nanobelt structures, it can be found that 5CAl is equivalent to cutting the last row of the 6CC atomic chain, so an Al atom appears at the lower edge. Similarly, 4AlAl is equivalent to cutting the first row of the 5CAl atomic chain, so an Al atom appears at both edges. Their band structures are shown as follows: Figure 3 (a), (b) and (c) in Figure 1. The nanoribbons of 6CC and 5CAl both cross the Fermi level, indicating that they are metals, while 4AlAl is an indirect bandgap semiconductor. From a structural perspective, if one edge contains aluminum atoms, the number of bands at the Fermi level decreases by one, and if both edges contain aluminum atoms, the number of bands continues to decrease by one and then becomes zero, thus changing the nanoribbon from a metal to a semiconductor. The results show that the edge morphology of the nanoribbon can effectively regulate its electronic properties.

[0058] from Figure 3 As can be seen from the nanoribbons and wave function diagrams in the figure, the wave functions of the energy bands above the Fermi level are all composed of the P atoms of the C atoms. x Orbital contribution, the wave functions of the energy bands below the Fermi level are all composed of the P z Orbital contribution, the wave function of the energy band passing through the Fermi level mainly comes from edge atoms and belongs to edge states.

[0059] The formula for calculating the formal energy is:

[0060]

[0061] Among them, E formation is the formation energy of the nanoribbon, E total is the total energy of C3Al; E Al ,E C and E H are the energies of isolated Al, C, and H atoms, and N Al 、N C and N H are the number of Al, C and H atoms, respectively. Table 1 shows the formation energies of XAlAl, XCAl and XCC nanoribbons, which are all close to the formation energy of graphene nanoribbons (-6.5 eV / atom), indicating that they have good stability.

[0062] Table 1 Formation energy of nanoribbons with different morphologies

[0063]

[0064]

[0065] S3, heterojunction devices were constructed using C3Al nanoribbons with different edge morphologies;

[0066] A step-shaped heterojunction (HJ) device composed of zigzag C3Al nanoribbons (ZC3AlNRs) with variable width was built. C3Al-HJ is used in the following text to represent heterojunction devices built by C3Al nanoribbons. The left side is a fixed 3CAl nanoribbon, and the right side is the three edge morphologies of the above C3Al nanoribbons. Therefore, C3Al-HJ devices are divided into three types: 3CAl-XCC, 3CAl-XCAl, and 3CAl-XAlAl.

[0067] In this embodiment, the right side of C3Al-HJ is three edge morphologies, which may specifically include: 4CC, 6CC, 8CC, 5CAl, 7CAl, 9CAl, 4AlAl, 6AlAl, and 8AlAl; Figure 4 (a), (b) and (c) show the structures of 3CAl-4CC, 3CAl-5CAl and 3CAl-4AlAl devices respectively. As the width on the right increases, the width difference between the left and right sides also increases.

[0068] Table 2 shows the total energy of the C3Al-HJ device, which shows good stability.

[0069] Table 2 Total energy of C3Al-HJ device

[0070]

[0071] S4, calculating the current value of the heterojunction device at different voltages;

[0072] The current value of the heterojunction device at different voltages is calculated according to the Landauer-Büttiker multi-terminal multi-channel formula; the current value calculation formula is:

[0073]

[0074] Where I(V) is the current value of the system, e is the electron charge, h is Planck's constant, and E is the energy value; μ L and μ R are the chemical potentials of the left and right electrodes, respectively, f(E-μ L ) and f(E-μ R ) are the Fermi distributions of the left and right electrodes, respectively, and V=(μ L -μ R) / e represents the bias window; T(E,V) is the spin-dependent transmission coefficient, T(E,V)=Tr[Γ L (E,V)G R (E,V)Γ R (E,V)G A (E,V)], where G R (E,V) and G A (E, V) are the delayed and advanced Green's functions in the scattering region, respectively, and Γ L and Γ R are the coupling matrices of the left (right) electrodes respectively.

[0075] In this example, the calculations were performed using the Atomistix Toolkit (ATK) software package, which is based on a combination of density functional theory (DFT) and non-equilibrium Green's function (NEGF) techniques. The Perdew-Burke-Ernzerhof formula of the generalized gradient approximation (GGA) was used as the exchange-correlation functional, and double Zeta polarization was used in the basis set calculations. The lattice cutoff energy was set to 150 Ry, and the K-point lattice was 1×1×150 in the Monkhorst-Park scheme. The vacuum space of the supercell was set to or larger to eliminate interactions with neighboring images. All atomic positions of the structure were optimized until all forces were less than The edges of ZC3AlNRs (zigzag C3Al nanoribbons with variable width) are terminated with hydrogen (H) atoms to eliminate dangling bonds.

[0076] The current-voltage (IV) characteristics of the C3Al-HJ device (a heterojunction device constructed by C3Al nanoribbons) are shown in Figure 2. Figure 5 As shown. For 3CAl-XCC devices, Figure 5 As shown in (a), in the range of -0.4V to 0.3V, the three IV curves almost overlap each other. As the forward bias increases, the current increases. When the forward bias reaches 0.4V, the current begins to decrease, showing a negative differential resistance effect. As the reverse bias increases, the current increases. When the reverse bias reaches -0.4V, the current begins to decrease, similar to the phenomenon under forward bias, also showing a negative differential resistance effect. Figure 5 In (b), the IV characteristics of the 3CAl-XCAl device show a negative differential resistance effect under both forward and negative bias, but the negative differential resistance effect becomes less obvious as the width of the nanoribbon increases, which will be discussed later. Figure 5In (c), the IV characteristics of the 3CAl-XAlAl device are completely different from the first two devices. It exhibits the characteristics of a unidirectional conducting rectifier diode. The current value of all three widths of the XAlAl device is zero between -0.7 and 0.5V. This is because the 3CAl nanoribbon on the left side of the device is a metal, while the XAlAl nanoribbon on the right side of the device is a semiconductor, so electron transition is relatively difficult. As the reverse bias increases, the current value increases. At the same time, when the forward bias increases, the current value is almost 0, that is, the 3CAl-XAlAl device exhibits a rectification phenomenon.

[0077] S5, designing the rectifier diode using the current value of the device;

[0078] In the present invention, heterojunction devices are constructed based on C3Al nanobelts with different edges, negative differential resistance effects occur in 3CAl-XCC and 3CAl-XCAl devices, rectification occurs in 3CAl-XAlAl devices, and the rectifying diode has unidirectional conductivity, so that the 3CAl-XAlAl device can be used to construct the rectifying diode, which greatly enriches the application of C3Al nanobelts in the field of electronic devices.

[0079] Example 2

[0080] Select 3CAl-4CC, 3CAl-5CAl and 3CAl-6AlAl devices and calculate their transmission spectra at different bias voltages. The results are as follows: Figure 6 shown. Figure 6 (a) shows the transmission spectra of 3CAl-4CC devices at biases of 0.2, 0.4, and 0.6 V; Figure 6 (b) is the transmission spectrum of 3CAl-5CAl device under 0.2, 0.4 and 0.6V bias; Figure 6 (c) in Figure 3 is the transmission spectrum of the 3CAl-6AlAl device at 0.4, 0.6 and 0.8 V bias. Figure 6 It can be found in (a) that with the increase of bias voltage, the transmission peak near the Fermi level of the 3CAl-4CC device first widens and then narrows. When the bias voltage increases from 0.2V to 0.4V, as the bias window increases, the integrated area increases significantly and the current also increases. However, when the bias voltage continues to increase to 0.6V, the transmission peak becomes significantly narrower, making the integrated area smaller and the current smaller, thus resulting in a negative differential resistance effect. Figure 6 In (b), for the 3CAl-5CAl device, when the forward bias is 0.6V, the transmission peaks of -0.1eV and 0.4eV are suppressed, which makes the integrated area smaller, the current smaller, and the negative differential resistance effect appears. Figure 6In (c), for the 3CAl-4AlAl device, in the range of 0.4V to 0.6V, the current increases from zero to something, but the transmission peak in the integrated area is relatively low.

[0081] At the same time, in order to study the effect of different nanoribbon widths on current, the transmission eigenstates of the XCAl structure under different nanoribbon widths were calculated. The transmission eigenstates of the XCAl structure under 0eV at 0.4V bias were selected for calculation. Figure 7 (a) is the transmission eigenstate of 5CAl nanoribbon at 0.4V bias at 0eV; Figure 7 (b) is the transmission eigenstate of 7CAl nanoribbon at 0.4V bias at 0eV; Figure 7 (c) is the transmission eigenstate of 9CAl nanoribbon at 0.4V bias at 0eV. Figure 7 It can be seen that the transmission channel of 5CAl is located at the edge. As the width increases, the transmission channel located at the upper edge becomes more and more localized, resulting in the suppression of transmission. Therefore, the transmission coefficient becomes smaller and smaller, and the current decreases.

[0082] The effect of the width on the electronic structure of these three ZC3 AlNRs was studied. The band diagram of the nanoribbons is shown in Figure 8 As shown, Figure 8 (a) is the energy band diagram of 4AlAl nanoribbon; Figure 8 (b) is the energy band diagram of 6AlAl nanoribbon; Figure 8 (c) is the energy band diagram of 8AlAl nanoribbon; Figure 8 (d) is the energy band diagram of 5CAl nanoribbons; Figure 8 (e) is the energy band diagram of 7CAl nanoribbon; Figure 8 (f) is the energy band diagram of 9CAl nanoribbon; Figure 8 (g) is the energy band diagram of 4CC nanoribbon; Figure 8 (h) is the energy band diagram of 6CC nanoribbon; Figure 8 (i) is the band diagram of 8CC nanoribbons. For all XCC structures, there are two bands crossing the Fermi level, and these two bands become more localized as the width increases. For all XCAl, only one band crosses the Fermi level. For XAlAl, all structures are indirect bandgap semiconductors, but the bandgap decreases with increasing width. Overall, the width has no substantial effect on the electronic properties of ZC3 AlNRs.

[0083] In the description of this specification, the description with reference to the terms "one embodiment", "example", "specific example", etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0084] The above shows and describes the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments, and the above embodiments and descriptions are only for explaining the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, and these changes and improvements all fall within the scope of the present invention to be protected.

Claims

1. A design method for a rectifier diode based on a C3Al heterojunction, characterized in that: The following steps are involved: The C3Al nanoribbons were cut into three edge morphologies; The energy band structure diagrams are calculated for the three edge morphologies of C3Al nanoribbons; Using the three edge morphologies of C3Al nanoribbons to build heterojunction devices respectively; Calculating the current value of the heterojunction device at different voltages; Design rectifier diodes using the current value of the device; The three edge morphologies are: (1) both edges have Al atoms, denoted as XAlAl; (2) one edge has no Al atoms and the other has Al atoms, denoted as XCAl; (3) both edges have C atoms, denoted as XCC; where X is the number of atoms across the width of the nanoribbon; The left side of the constructed heterojunction device is a 3CAl nanobelt, and the right side is three edge morphologies of the C3Al nanobelt. The heterojunction device includes the following three types: 3CAl-XCC, 3CAl-XCAl, and 3CAl-XAlAl; Heterojunction devices are built based on C3Al nanoribbons with different edges. Negative differential resistance effect occurs in 3CAl-XCC and 3CAl-XCAl devices, rectification occurs in 3CAl-XAlAl devices, and the rectifying diode has unidirectional conductivity, so 3CAl-XAlAl devices can be used to build rectifying diodes.

2. The design method of a rectifier diode based on a C3Al heterojunction according to claim 1, characterized in that: The bond lengths of the CC bond and the Al-C bond in C3Al are and 3. The design method of a rectifier diode based on a C3Al heterojunction according to claim 1, characterized in that: According to the energy band structure diagram and C3Al nanobelt structure analysis, C3Al nanobelts with different edge morphologies will undergo a transition from metal to semiconductor.

4. The design method of a rectifier diode based on a C3Al heterojunction according to claim 1, characterized in that: The calculation formula of the current value of the heterojunction device is: When calculating the current value of a heterojunction device at different voltages, the current value is calculated according to the Landauer-Büttiker multi-terminal multi-channel formula: Where I(V) is the current value of the system, e is the electron charge, h is Planck's constant, and E is the energy value; μ L and μ R are the chemical potentials of the left and right electrodes, respectively, f(E-μ L ) and f(E-μ R ) are the Fermi distributions of the left and right electrodes, respectively, and V=(μ L -μ R ) / e represents the bias window; T(E, V) is the spin-dependent transmission coefficient; The calculation formula of T(E, V) is: T(E, V)=Tr[Γ L (E, V)G R (E, V)Γ R (E, V)G A (E, V)] Among them, G R (E, V) and G A (E, V) are the delayed and advanced Green's functions in the scattering region, respectively, and Γ L and Γ R are the coupling matrices of the left (right) electrodes respectively.

5. A rectifier diode, characterized in that: The rectifier diode is designed using the design method based on the C3Al heterojunction as described in any one of claims 1 to 4.

6. A method for constructing a heterojunction device, characterized in that: The following steps are involved: The C3Al nanoribbons were cut into three edge morphologies; The energy band structure diagrams are calculated for the three edge morphologies of C3Al nanoribbons; Using the three edge morphologies of C3Al nanoribbons to build heterojunction devices respectively; The three edge morphologies are: (1) both edges have Al atoms, denoted as XAlAl; (2) one edge has no Al atoms and the other has Al atoms, denoted as XCAl; (3) both edges have C atoms, denoted as XCC; where X is the number of atoms across the width of the nanoribbon; The left side of the constructed heterojunction device is a 3CAl nanobelt, and the right side is three edge morphologies of the C3Al nanobelt. The heterojunction device includes the following three types: 3CAl-XCC, 3CAl-XCAl and 3CAl-XAlAl.

7. A heterojunction device, characterized in that: The heterojunction device is constructed using the construction method of claim 6.

8. Use of the heterojunction device according to claim 7 in building a rectifier diode.

Images