Negative resistance effect control method based on non-uniform distribution of space charge

Abstract

The present invention discloses a method for regulating the negative resistance effect based on the non-uniform distribution of spatial charges. A plurality of metal electrodes with different spacings are prepared on the same surface of a semiconductor material, wherein two electrodes are respectively located on both sides of the surface of the material, and the positive and negative electrodes of a current source are respectively connected to the electrodes on both sides, and the positive electrode of a voltmeter is connected to the metal electrode connected to the positive electrode of the current source, and the negative electrode of the voltmeter is connected to the remaining electrode. A minority carrier equivalent injection effect based on local impact ionization is formed in the semiconductor, and then the negative resistance effect is measured by a voltmeter; based on the non-uniform distribution of spatial charges, the position of the electrode to which the negative electrode of the voltmeter is connected is changed, so that the effective carrier concentration in the area detected by the voltmeter changes, thereby realizing the regulation of the detected negative resistance effect. The regulation method involved in the present invention is continuously adjustable and has a simple process, and is convenient for application in new multi-performance negative resistance element integrated circuits.

Description

Technical Field

[0001] The present invention belongs to the field of semiconductor electronic device performance regulation and control, and in particular relates to a negative resistance effect regulation method based on non-uniform distribution of spatial charges. Background Art

[0002] Negative resistance effect generally refers to a nonlinear electrical transport effect in which the measured voltage decreases while the applied current increases, or the measured current decreases during the process of applied voltage increasing. Devices based on negative resistance effect can be applied to circuit amplifiers, memories, logic circuits, oscillators, pulse generators and other fields, and have very important application prospects.

[0003] At present, negative resistance effect has been found in a variety of materials and structures, such as Si, GaAs, graphene, silicon-based pn heterojunction structures, etc. However, the regulation of negative resistance effect often requires complex structural design processes or specific conditions (such as light or external magnetic field, etc.), and it is difficult to achieve negative resistance effects of different intensities in the same device, which is not convenient for integrated application, thus limiting its wider application to a certain extent. Summary of the invention

[0004] The technical problem to be solved by the present invention is to provide a method for regulating the negative resistance effect based on the non-uniform distribution of spatial charges, so as to solve the problem that realizing the negative resistance effect often requires the use of complex structural design processes or specific conditions (such as light or external magnetic field, etc.), and it is difficult to realize multiple negative resistance effects with different intensities in the same device, which is not convenient for integrated application.

[0005] In order to solve the above technical problems, the technical solution adopted by the present invention is: a negative resistance effect control method based on non-uniform distribution of space charge, comprising the following steps:

[0006] 1) Preparing a plurality of metal electrodes with different spacings on the same surface of a semiconductor material, wherein two electrodes are located on two sides of the surface of the material respectively;

[0007] 2) Connect the positive and negative electrodes of the current source to the two metal electrodes respectively, and connect the positive electrode of the voltmeter to the metal electrode to which the positive electrode of the current source is connected, and the negative electrode of the voltmeter to one of the other metal electrodes in turn;

[0008] 3) When the current is continuously increased through the current source, a strong local electric field is induced inside the semiconductor, resulting in local collision ionization and a minority carrier equivalent injection effect, so that the negative resistance effect in the semiconductor material is measured by the voltmeter. At this time, the space charge in the semiconductor is in a non-uniform distribution state. By changing the position of the metal electrode connected to the negative pole of the voltmeter, the effective carrier concentration in the area detected by the voltmeter changes, thereby realizing the regulation of the detected negative resistance effect.

[0009] In a preferred embodiment, the semiconductor substrate is one of low-doped non-magnetic semiconductor materials Ge, Si, GaAs or GaSb.

[0010] In a preferred embodiment, the metal electrode material is one of the non-magnetic metals Au, Ag, Cu, In or Al.

[0011] In a preferred embodiment, an ohmic contact characteristic is formed between the metal electrode material and the semiconductor material.

[0012] The negative resistance effect control method based on non-uniform distribution of space charge provided by the present invention has the following beneficial effects by adopting the above structure:

[0013] (1) The method of the present invention is based on the negative resistance effect caused by local impact ionization. By changing the distance between electrodes connected to the voltmeter, the effective carrier concentration in the voltage detection area is adjusted to achieve the regulation of the detected negative resistance effect. It has the advantage of being able to achieve continuous adjustment of the negative resistance effect by continuously changing the distance between electrodes, and is easy to be applied in multi-performance negative resistance element integrated circuits.

[0014] (2) The method of the present invention has a simple process and a mature device performance testing method, which is conducive to promotion and application. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] The present invention will be further described below in conjunction with the accompanying drawings and embodiments:

[0016] Figure 1 Schematic diagram of the measurement of the negative resistance effect control method based on the non-uniform distribution of space charge in an embodiment of the present invention.

[0017] Figure 2 The current in the smaller current range measured by taking electrodes No. 1 and No. 5 as examples in the embodiment of the present invention is V - I Curve result graph.

[0018] Figure 3 This is a graph of VI curve results within a larger current range measured under different electrode spacing conditions in an embodiment of the present invention.

[0019] Figure 4 In the embodiment of the present invention V - I The negative resistance conduction interval of the curve corresponds to |d V / d I |Graph showing the relationship between the maximum value and the electrode spacing.

[0020] Figure 5 The results of the embodiment of the present invention after eliminating the influence of magnetoresistance signal under the conditions of 300 K and 1 T magnetic field are shown in FIG.V H - I Graph.

[0021] Figure 6 It is a schematic diagram of the principle of non-uniform distribution of space charge in a semiconductor in an embodiment of the invention. DETAILED DESCRIPTION

[0022] like Figure 1 As shown, in one embodiment of the present invention, the semiconductor material is a non-magnetic semiconductor Ge with low Ga doping, denoted as p-Ge:Ga, and the material of the metal electrode is Au. The specific preparation method of the non-magnetic semiconductor and the metal electrode and the electrode spacing and other information are as follows:

[0023] Select non-magnetic p-Ge:Ga semiconductor material, the room temperature resistivity of which is 10-30 Ω·cm and the thickness is 0.5 mm. Use an alloy engraving pen to cut out a piece of 8.00×8.00 mm 2 The square p-Ge:Ga semiconductor material was measured by the Van der Pauw method at 300 K. The carrier concentration and mobility of the selected semiconductor material without minority carrier injection were approximately 2.61×10 14 cm -3 and 2.05×10 3 cm 2 ·V -1 ·s -1 . Use an alloy engraving pen to cut out a rectangular strip sample with an average length of about 3.10 mm and an average width of about 1.26 mm. The cut strip samples were ultrasonically cleaned with acetone and anhydrous ethanol for 10 minutes in sequence to ensure that the surface of the substrate material was cleaned. Finally, the cleaned semiconductor strip samples were taken out and the surface was blown dry with argon gas. Five metal Au electrodes with different spacings were prepared on the same surface of the semiconductor strip sample by high vacuum magnetron sputtering coating combined with a mask method. One of the metal electrodes was located on the side of the material surface, and then a wire was led out through silver paste to connect the current source and voltmeter required for the test. For the convenience of description, the prepared metal electrodes are numbered 1-5 in sequence. Among them, electrodes No. 1 and No. 5 are located on both sides of the surface of the material, respectively. The spacing between electrodes No. 1 and No. X (X=2, 3, 4 or 5) is marked as L 1X , then L 12 , L 13 , L 14 and L 15 They are approximately 0.4 mm, 1.1 mm, 1.8 mm and 2.5 mm respectively.

[0024] like Figure 1As shown, in the embodiment of the present invention, the positive and negative poles of the current source are connected to the No. 1 and No. 5 Au electrodes respectively, and the positive pole of the voltmeter is connected to the No. 1 Au electrode, and the negative pole of the voltmeter is connected to the No. X (X=2, 3, 4 or 5) Au electrodes in sequence. The device is in a dark environment, and except for the subsequent Hall effect measurement, the measurements of other electrical transport properties of the device are in an environment without an external magnetic field. Taking the case where the negative pole of the voltmeter is connected to the No. 5 Au electrode as an example, the voltage in a smaller current range is measured ( V )-Current( I ) curve, the results are as follows Figure 2 As shown. Figure 2 It can be seen that the obtained V - I The curve is a straight line passing through the origin, indicating that an ohmic contact is formed between the prepared Au electrode and the selected non-magnetic p-Ge:Ga semiconductor.

[0025] like Figure 3 The figure shows the negative terminal of the voltmeter connected to the Au electrode X (X = 2, 3, 4 or 5). V - I The curve results are Figure 3 It can be seen that the negative resistance effect can be observed under different electrode spacing conditions. This is because when the current source continues to increase the current, a strong local electric field is induced inside the non-magnetic p-Ge:Ga semiconductor, resulting in local collision ionization and the equivalent injection effect of minority carriers. According to the calculation formula of semiconductor resistance R R = L / S [( nq n + pq p )], where μ n , μ p are the electron mobility and hole mobility in the semiconductor, q is the charge, L is the distance between electrodes 1 and 5, S is the cross-sectional area of ​​the semiconductor perpendicular to the direction of current flow. q , L and S The value remains unchanged and at a constant temperature, μ n , μ p It can also be regarded as a constant. After the minority carrier equivalent injection effect occurs, the electron concentration n Gradually increases, at this time the hole concentration p The change of is approximately negligible, so RGradually begins to decrease, showing a negative resistance effect. That is, when the measured voltage reaches a certain maximum value, the current continues to increase, and the negative resistance effect in the semiconductor material can be measured by the voltmeter. Figure 4 It can be seen that |d V / d I The maximum value increases significantly with the increase of the electrode spacing, indicating that the negative resistance effect can be continuously controlled by continuously changing the electrode spacing.

[0026] Using the same high vacuum coating process, two Au electrodes were prepared on the semiconductor surface parallel to the current direction of Au electrodes 1 and 5 to collect the Hall voltage ( V H ) signal, applying a 1 T magnetic field perpendicular to the current direction and the electrode connection direction of VH signal collection, and measuring the positive 1 T and negative 1 T magnetic field directions to obtain V H - I The curve data is processed by antisymmetric calculation to eliminate the possible interference of magnetic resistance signal in the Hall effect measurement signal. The results are as follows Figure 5 As shown. Through the Hall effect measurement results, it can be found that in a smaller current range V H is a positive value, indicating that the selected semiconductor material is indeed p-type doping type; as the current gradually increases, V H As the current increases first and then gradually decreases, when the current is greater than about 20mA, V H It changes from a positive value to a negative value, and remains in the negative range as the current continues to increase, indicating that a significant minority carrier injection effect does occur under higher current conditions. Figure 3 and Figure 5 It can be found that the current corresponding to the negative resistance effect is almost the same as V H The current magnitudes corresponding to the change from positive to negative are equal, indicating that the negative resistance effect is indeed mainly derived from the equivalent injection effect of minority carriers generated when local impact ionization occurs.

[0027] In the case of minority carrier injection, such as Figure 6As shown, the spatial charge in the semiconductor is non-uniformly distributed. By changing the position of the Au metal electrode to which the negative pole of the voltmeter is connected, that is, the negative pole of the voltmeter is connected to Au electrodes No. 2 to No. 5 in sequence, there will be a difference in the effective carrier concentration in the area detected by the positive and negative poles of the voltmeter, thereby achieving the regulation of the detected negative resistance effect. For example, the effective carrier concentration between electrodes No. 1 and No. 2 is significantly lower than the effective carrier concentration between electrodes No. 1 and No. 5. Therefore, the negative resistance effect detected when the voltmeter is connected to electrodes No. 1 and No. 2 is weaker than the negative resistance effect detected when it is connected to electrodes No. 1 and No. 5 (such as Figure 3 and Figure 4 as shown).

[0028] It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described can be combined with each other as long as they do not conflict with each other.

Claims

1. A method for controlling negative resistance effect based on non-uniform distribution of space charge, characterized in that The following steps are involved: 1) preparing a plurality of metal electrodes with different spacings on the same surface of a semiconductor material, wherein a first and a last metal electrode of the plurality of metal electrodes are respectively located on two sides of the surface of the semiconductor material; 2) Connect the positive and negative electrodes of the current source to the first and last metal electrodes on the surface of the semiconductor material respectively, and connect the positive electrode of the voltmeter to the first metal electrode, and the negative electrode of the voltmeter to one of the second to last metal electrodes in sequence; 3) When the current is continuously increased through the current source, a strong local electric field is induced inside the semiconductor, resulting in local collision ionization and a minority carrier equivalent injection effect, so that the negative resistance effect in the semiconductor material is measured by the voltmeter. At this time, the space charge in the semiconductor is in a non-uniform distribution state. By changing the position of the metal electrode connected to the negative pole of the voltmeter, the effective carrier concentration in the area detected by the voltmeter changes, thereby realizing the regulation of the detected negative resistance effect.

2. The method for controlling negative resistance effect based on non-uniform distribution of space charge according to claim 1, characterized in that: The semiconductor substrate is one of low-doped non-magnetic semiconductor materials Ge, Si, GaAs or GaSb.

3. The method for controlling negative resistance effect based on non-uniform distribution of space charge according to claim 1, characterized in that: The metal electrode material is one of non-magnetic metals Au, Ag, Cu, In or Al.

4. The method for controlling negative resistance effect based on non-uniform distribution of space charge according to claim 1, characterized in that: An ohmic contact characteristic is formed between the metal electrode material and the semiconductor material.

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