Diode, rectifier circuit, power receiving device, and wireless power transmission device

Abstract

To provide a diode capable of rectifying low-power high-frequency radio waves, a rectifier circuit with high rectification efficiency, and a power receiving device and wireless power transmission device with high conversion efficiency.SOLUTION: A diode 100 comprises: a semiconductor region in which a current path is formed; first and second electrodes E1 and E2 which are disposed apart from each other and ohmic-joined to the semiconductor region; and a third electrode E3 which is disposed between the first and second electrodes, electrically connected to the first electrode, and Schottky-joined to the semiconductor region. The first electrode and the third electrode serve as anode electrodes, and the second electrode serves as a cathode electrode. The semiconductor region includes a region composed of AlGaAs and / or GaAs Schottky-joined to the third electrode. The third electrode has a solid-phase diffusion region 106 of a predetermined depth in which platinum is solid-phase diffused into the region composed of AlGaAs and / or GaAs. There are also provided a rectifier circuit including the diode, a power receiving device and a wireless power transmission device including the rectifier circuit.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a diode suitable for use as a rectifier diode for converting high-frequency radio waves into direct current, a rectifier circuit using this diode as a rectifier diode, and a power receiving device and a wireless power transmission device including this rectifier circuit. [Background technology]

[0002] In recent years, active research has been conducted into the practical application of wireless power transmission using high-frequency radio waves in the microwave band. A typical wireless power transmission device is configured such that a power receiving device receives high-frequency radio waves transmitted from a power transmitting device, and a rectifier circuit converts the input high-frequency radio waves into DC power and outputs it to a load.

[0003] In a power receiving device, the performance (rectification efficiency) of the rectifier diode in the rectifier circuit significantly affects the radio frequency (RF) / direct current (DC) conversion efficiency. For this reason, Schottky barrier diodes are often used as rectifier diodes (for example, Patent Document 1). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 6304520 Summary of the Invention [Problem to be solved by the invention]

[0005] In a wireless power transmission device using high-frequency radio waves, the high-frequency radio waves transmitted from the power transmitting device experience large losses due to spatial propagation, and the power of the high-frequency radio waves received by the power receiving device is very small. In order to convert this low-power high-frequency radio waves into DC power with high efficiency, it is preferable that the on-voltage (forward rise voltage Vf) of the rectifier diode in the rectifier circuit be low.

[0006] Schottky barrier diodes made of compound semiconductors and used as rectifier diodes for high-frequency radio waves generally have a high on-state voltage due to the wide band gap of the compound semiconductor. As an example, the band gap of gallium arsenide (GaAs) is relatively wide at 1.43 eV, resulting in an on-state voltage of approximately 0.6 to 0.7 V. For this reason, power receiving devices and the like equipped with rectifier circuits that use Schottky barrier diodes made of compound semiconductors as rectifier diodes have a problem of low conversion efficiency for low-power high-frequency radio waves.

[0007] On the other hand, Schottky barrier diodes made of silicon (Si) semiconductors have a band gap of 1.12 eV, which is narrower than that of compound semiconductors, and have an on-state voltage of approximately 0.3 V. Therefore, power receiving devices and other devices equipped with rectifier circuits that use Schottky barrier diodes made of silicon semiconductors as rectifier diodes have a relatively high conversion efficiency for low-power radio-frequency waves. However, compared to Schottky barrier diodes made of compound semiconductors, they have a slower operating speed and are limited in the frequency band of radio-frequency waves they can convert. Furthermore, although their on-state voltage is low at approximately 0.3 V and they are capable of converting low-power radio-frequency waves, there is also the problem that their conversion of even lower-power radio-frequency waves is also limited.

[0008] Therefore, an object of the present invention is to provide a diode capable of rectifying low-power high-frequency radio waves, a rectifier circuit with high rectification efficiency, a power receiving device with high conversion efficiency, and a wireless power transmission device. [Means for solving the problem]

[0009] A diode according to one aspect of the present invention comprises a semiconductor region in which a current path is formed, a first electrode and a second electrode spaced apart from each other and forming an ohmic junction with the semiconductor region, and a third electrode disposed between the first electrode and the second electrode, electrically connected to the first electrode, and forming a Schottky junction with the semiconductor region, the diode having the first electrode and the third electrode as anode electrodes and the second electrode as a cathode electrode, and the semiconductor region has a region made of AlGaAs and / or GaAs that forms a Schottky junction with the third electrode, The third electrode has a solid-phase diffusion region in which platinum has been solid-phase diffused into the region composed of AlGaAs and / or GaAs, and the solid-phase diffusion region has a depth such that, when the voltage applied to the anode electrode is in a zero bias state, a depletion layer formed in the semiconductor region below the solid-phase diffusion region depletes the current path, blocking the current path, and when a positive voltage exceeding the voltage applied in a zero bias state is applied to the anode electrode, the width of the depletion layer narrows and the current path is formed.

[0010] Another aspect of the present invention is a rectifier circuit that converts input high-frequency radio waves into DC power and outputs it, the rectifier circuit having a rectifier diode that converts the high-frequency radio waves into DC power, and the rectifier diode is configured with the above-mentioned diode.

[0011] Another aspect of the present invention is a power receiving device that includes an antenna for receiving high-frequency radio waves and a rectifier circuit that inputs the high-frequency radio waves, converts them into DC power, and outputs it, wherein the rectifier circuit has a rectifier diode that converts the high-frequency radio waves into DC power, and the rectifier diode is configured as the above-mentioned diode.

[0012] Yet another aspect of the present invention is a wireless power transmission device comprising a power transmitting device having a power transmitting circuit that generates high-frequency radio waves and an antenna that transmits the high-frequency radio waves, and a power receiving device having an antenna that receives the high-frequency radio waves and a rectifying circuit that receives the high-frequency radio waves, converts them into DC power, and outputs the power, wherein the rectifying circuit has a rectifying diode that converts the high-frequency radio waves into DC power, and the rectifying diode is configured as the above-mentioned diode. [Effects of the Invention]

[0013] The diode of the present invention has a low on-state voltage and is capable of rectifying low-power high-frequency radio waves.

[0014] Furthermore, the rectifier circuit of the present invention has a rectifier diode capable of rectifying low-power high-frequency radio waves with a low on-voltage, thereby enabling rectification with high rectification efficiency.

[0015] Furthermore, according to the power receiving device and wireless power transmission device of the present invention, by providing a rectifier circuit with high rectification efficiency, it is possible to configure a power receiving device and wireless power transmission device with high conversion efficiency. [Brief explanation of the drawings]

[0016] [Figure 1] FIG. 1 is an explanatory diagram of one embodiment (first embodiment) of a diode according to one aspect of the present invention, and is a schematic plan view of the diode. [Figure 2] 2 is a cross-sectional view of the diode of FIG. 1 taken along line XX. [Figure 3] 4A to 4C are diagrams illustrating the operation of the diode of the first embodiment. [Figure 4] 4A to 4C are diagrams illustrating the operation of the diode of the first embodiment. [Figure 5] FIG. 3 is a diagram illustrating the current-voltage characteristics of the diode of the first embodiment. [Figure 6] FIG. 2 is an explanatory diagram of another embodiment (Embodiment 2) of the diode according to an aspect of the present invention, and is a schematic cross-sectional view of the diode. [Figure 7]10A and 10B are diagrams illustrating the operation of the diode of the second embodiment. [Figure 8] 10A and 10B are diagrams illustrating the operation of the diode of the second embodiment. [Figure 9] FIG. 10 is an explanatory diagram of an embodiment (Embodiment 3) of a rectifier circuit according to another aspect of the present invention. [Figure 10] FIG. 10 is a diagram showing the relationship between input power and rectification efficiency of the rectifier circuit of the third embodiment. [Figure 11] FIG. 10 is an explanatory diagram of an embodiment (fourth embodiment) of a power receiving device according to still another aspect of the present invention. [Figure 12] FIG. 10 is an explanatory diagram of another embodiment (fifth embodiment) of a power receiving device, which is still another aspect of the present invention. [Figure 13] 10 is an explanatory diagram of a rectifier diode of a rectifier circuit that configures a power receiving device according to a fifth embodiment. FIG. [Figure 14] FIG. 10 is an explanatory diagram of a wireless power transmission device according to a sixth embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0017] Next, embodiments of the diode, rectifier circuit, power receiving device, and wireless power transmission device of the present invention will be described with reference to the drawings, but the present invention is not limited to these embodiments, and the members, materials, etc. described below can be modified in various ways within the scope of the present invention. Furthermore, the same reference numerals in the drawings indicate equivalent or identical parts, and the size and positional relationship between each component is for convenience's sake.

[0018] (Embodiment 1) First, an embodiment of a diode according to the present invention will be described. FIG. 1 is an explanatory diagram of one embodiment (Embodiment 1) of a diode according to the present invention, and is a schematic plan view of the diode. FIG. 2 is a schematic cross-sectional view of the diode taken along line XX of FIG. 1. As shown in FIGS. 1 and 2, a diode 100 according to this embodiment includes, for example, a buffer layer 102, a channel layer 103 made of undoped indium gallium arsenide (InGaAs), a carrier supply layer 104 made of highly doped n-type aluminum gallium arsenide (AlGaAs), and a contact layer 105 made of highly doped n-type GaAs, disposed on a substrate 101 made of semi-insulating GaAs, and formed in a semiconductor region surrounded by an isolation region 108. The contact layer 105 may be configured to include a highly doped n-type region in the carrier supply layer 104, instead of being disposed on the carrier supply layer 104.

[0019] A first electrode E1 and a second electrode E2 are disposed on each contact layer 105, respectively, and form an ohmic junction with the contact layer 105. The first electrode E1 and the second electrode E2 can be formed of, for example, a stacked metal of AuGe / Ni / Au. A third electrode E3 is disposed on the carrier supply layer 104, and forms a Schottky junction with the carrier supply layer 104. The third electrode E3 has a solid-phase diffusion region 106 in the carrier supply layer 104. This solid-phase diffusion region 106 is formed, for example, by stacking Pt / Ti / Pt / Au on the surface of the carrier supply layer 104 in this order, followed by heat treatment, thereby causing solid-phase diffusion of platinum, which is directly deposited on the carrier supply layer 104, into the carrier supply layer 104. When the carrier supply layer 104 is made of AlGaAs, the solid-phase diffusion region 106 is formed by diffusing platinum, which is directly deposited on the carrier supply layer 104, to a depth twice the thickness of the layer. The solid-phase diffusion region 106 constitutes a part of the third electrode E3, and is disposed so as to reach a depth at which desired diode characteristics, which will be described later, can be obtained. The carrier supply layer 104 is set to a thickness and impurity concentration that will result in a diode with low on-resistance and high breakdown voltage, and therefore the thickness of the platinum layer that is stacked directly on the carrier supply layer 104 is set according to the thickness of the carrier supply layer 104.

[0020] In the diode 100 of this embodiment, a two-dimensional electron gas layer 107 is formed at the heterointerface between the channel layer 103 and the carrier supply layer 104. This two-dimensional electron gas layer 107 becomes part of the current path.

[0021] Next, the operation of the diode 100 of this embodiment will be described. Figures 3 and 4 are diagrams for explaining the operation of the diode of this embodiment. The first electrode E1 and the third electrode E3 are electrically connected, and the first electrode E1 and the third electrode E3 serve as the anode electrode A of the diode 100, and the second electrode E2 serves as the cathode electrode C.

[0022] In the diode 100 of this embodiment, when there is no potential difference between the voltage applied to the anode electrode A and the voltage applied to the cathode electrode C (hereinafter referred to as the "zero bias state"), as shown in FIG. 3, a depletion layer 109 is formed below the solid-phase diffusion region 106. The depletion layer is formed by the Schottky junction of the solid-phase diffusion region 106 with the carrier supply layer 104, and the depletion layer is formed at the heterojunction of the junction interface between the channel layer 103 and the carrier supply layer 104. This causes the two-dimensional electron gas in the two-dimensional electron gas layer 107 to disappear (the current path is depleted), and the current path between the anode electrode A and the cathode electrode C is blocked. At this time, the width of the depletion layer 109 in the depth direction (hereinafter referred to as the "depletion layer width") is set to the narrowest width necessary to block the current path by eliminating the two-dimensional electron gas. In this state, no current flows between the anode electrode A and the cathode electrode C.

[0023] When a positive voltage exceeding the voltage (0 V) applied in a zero-bias state is applied to the anode electrode A, the width of the depletion layer 109 formed in the carrier supply layer 104 below the solid-phase diffusion region 106 narrows, two-dimensional electron gas is generated, a current path consisting of the two-dimensional electron gas layer 107 is formed, and current begins to flow between the anode electrode A and the cathode electrode C, as shown in Figure 4. When the voltage applied to the anode electrode A is further increased, the concentration of the two-dimensional electron gas in the two-dimensional electron gas layer 107 increases, and the current flowing between the anode electrode A and the cathode electrode C increases, resulting in diode characteristics.

[0024] As shown in FIG. 3 , when the depletion layer 109 is formed so as to deplete the two-dimensional electron gas layer 107 and not to extend significantly toward the channel layer 103, the on-voltage of the diode 100, at which current begins to flow between the anode electrode A and the cathode electrode C, can be set to approximately 0 V. A rectifier circuit having the diode 100 of this embodiment configured as a rectifier diode can rectify low-power high-frequency radio waves with high efficiency. Furthermore, a power receiving device and a wireless power transmission device including a rectifier circuit having the diode 100 as a rectifier diode can convert low-power high-frequency radio waves with high efficiency. Furthermore, the two-dimensional electron gas in the channel layer, which is made of InGaAs with high carrier mobility, has the advantage of reducing the series resistance of the current path.

[0025] However, since the width of the depletion layer 109 is determined by the metal constituting the third electrode E3, the semiconductor constituting the carrier supply layer 104, and the impurity concentration thereof, it may be difficult to design the width of the depletion layer 109 in the zero bias state shown in Figure 3 so that it matches the width that blocks the current path.

[0026] Therefore, in the diode 100 of this embodiment, the third electrode E3 has a solid-phase diffusion region 106, and the desired diode characteristics can be obtained by controlling the depth at which this solid-phase diffusion region 106 is formed. As an example, in a zero-bias state, no current flows between the anode electrode A and the cathode electrode C, or only a current of less than 10 μA flows, at which point the current path is considered to be blocked. When a positive potential exceeding the voltage in the zero-bias state is applied to the anode electrode A, two-dimensional electron gas is generated, forming a two-dimensional electron gas layer 107, and a current path including the two-dimensional electron gas layer 107 is formed. The solid-phase diffusion region 106 is disposed at a depth at which a depletion layer 109 is formed, so that a current path including the two-dimensional electron gas layer 107 is formed.

[0027] In this type of diode, the impurity concentration of the carrier supply layer 104 is set high, and a semiconductor layer for reducing the band gap difference may be formed on the carrier supply layer 104. As an example, an undoped AlGaAs layer, in which the Al content decreases toward the surface, is disposed on the carrier supply layer 104 made of AlGaAs as a band gap reduction layer, and an undoped GaAs layer is disposed on the undoped AlGaAs layer. Therefore, the depth at which the solid-phase diffusion region 106 is formed is determined depending on the impurity concentration of the carrier supply layer 104, the configuration and thickness of the semiconductor region in which the third electrode E3 is formed, and other factors. The solid-phase diffusion region 106 can be formed to a predetermined depth with good control by setting the thickness of the platinum layer directly deposited on the carrier supply layer 104 (or the band gap reduction layer, if a band gap reduction layer is formed) to a predetermined thickness.

[0028] Fig. 5 is a diagram illustrating the current-voltage characteristics of the diode of this embodiment. In Fig. 5, the characteristics of the diode 100 of this embodiment are shown by a solid line, and the characteristics of a Schottky barrier diode made of a silicon semiconductor as a comparative example are shown by a dashed line. If the voltage at a current of 10 μA is taken as the on-voltage of the diode, as shown in Fig. 5, the on-voltage of the Schottky barrier diode made of a silicon semiconductor as the comparative example is 0.3 V, while the on-voltage of the diode of this embodiment is approximately 0.025 V, making it a diode with an extremely low on-voltage.

[0029] 1 to 4, the diode of this embodiment is not limited to the configuration shown in FIGS. 1 to 4 as long as the carrier supply layer or the like into which platinum constituting the third electrode E3 undergoes solid-phase diffusion includes a semiconductor region containing AlGaAs and / or GaAs forming a Schottky junction. For example, a barrier layer may be disposed between the channel layer 103 and the carrier supply layer 104. Alternatively, another carrier supply layer may be disposed on the substrate 101 side of the channel layer 103. An indium gallium phosphide (InGaP) layer may be disposed on the exposed carrier supply layer 104 as a semiconductor region with a low surface state density to suppress the formation of a surface depletion layer.

[0030] (Embodiment 2) Next, another embodiment of a diode according to the present invention will be described. FIG. 6 is an explanatory diagram of another embodiment (Embodiment 2) of a diode according to the present invention, showing a schematic cross-sectional view of the diode. The electrode arrangement of a diode 200 according to this embodiment can be the same as that shown in FIG. 1 described in Embodiment 1 above, and the schematic cross-sectional view of FIG. 6 corresponds to the schematic cross-sectional view of the diode 100 taken along line XX in FIG. 1. As shown in FIG. 6, the diode 200 according to this embodiment includes, for example, a substrate 201 made of semi-insulating gallium arsenide (GaAs) on which a low-concentration n-type semiconductor region 202 is disposed by ion implantation, and a contact layer 203 made of high-concentration n-type GaAs is disposed on the semiconductor region 202. Instead of disposing the contact layer 203 on the semiconductor region 202, a high-concentration n-type region can also be disposed in the semiconductor region 202 by ion implantation.

[0031] A first electrode E1 and a second electrode E2 are disposed on each contact layer 203, forming an ohmic junction with the contact layer 203. The first electrode E1 and the second electrode E2 may be formed of, for example, a stacked metal of AuGe / Ni / Au. A third electrode E3 is disposed on the semiconductor region 202, forming a Schottky junction with the semiconductor region 202. The third electrode E3 has a solid-phase diffusion region 204 in the semiconductor region 202. The solid-phase diffusion region 204 is formed, for example, by stacking Pt / Ti / Pt / Au on the surface of the semiconductor region 202 in this order, followed by heat treatment, thereby causing solid-phase diffusion of platinum, which is stacked directly on the semiconductor region 202, into the semiconductor region 202. When the semiconductor region 202 is made of GaAs, the solid-phase diffusion region 204 is formed by diffusing platinum, which is stacked directly on the semiconductor region 202, to a depth twice the thickness of the platinum. The solid-phase diffusion region 204 constitutes a part of the third electrode E3, and is disposed so as to reach a depth at which the desired diode characteristics described below can be obtained. The semiconductor region 202 is set to a thickness and impurity concentration that will form a diode with low on-resistance and high breakdown voltage, and therefore the thickness of the platinum layer deposited directly on the semiconductor region 202 is set according to the thickness of the semiconductor region 202.

[0032] Next, the operation of the diode 200 of this embodiment will be described. Figures 7 and 8 are diagrams illustrating the operation of the diode of this embodiment. In the diode 200 of this embodiment, similar to the diode 100 of the first embodiment, the first electrode E1 and the third electrode E3 are electrically connected, and the first electrode E1 and the third electrode E3 serve as the anode electrode A of the diode 200, and the second electrode E2 serves as the cathode electrode C.

[0033] In the diode 200 of this embodiment, when the voltage applied to the anode electrode A and the voltage applied to the cathode electrode C are in a zero bias state, as shown in Fig. 7, a depletion layer 205 is formed below the solid-phase diffusion region 204 by a Schottky junction between the solid-phase diffusion region 204 and the semiconductor region 202, and the current path between the anode electrode A and the cathode electrode C is blocked. At this time, the width of the depletion layer 205 is set to match the narrowest width at which the semiconductor region 202 is depleted and the current path is blocked. In this state, no current flows between the anode electrode A and the cathode electrode C.

[0034] When a positive voltage exceeding the voltage (0 V) applied in a zero-bias state is applied to the anode electrode A, the width of the depletion layer 205 formed in the semiconductor region 202 below the solid-phase diffusion region 204 narrows, forming a current path in the semiconductor region 202 and allowing current to flow between the anode electrode A and the cathode electrode C, as shown in Figure 8. When the voltage applied to the anode electrode A increases further, the width of the depletion layer 205 narrows further, increasing the current flowing between the anode electrode A and the cathode electrode C, and achieving diode characteristics.

[0035] In this manner, also in this embodiment, as shown in FIG. 7, if the depletion layer 205 is formed so as to deplete the semiconductor region 202 and not to extend significantly toward the substrate 201, the on-voltage of the diode 200 at which current begins to flow between the anode electrode A and the cathode electrode C can be set to approximately 0 V.

[0036] A rectifier circuit having the diode 200 of this embodiment as a rectifier diode can rectify low-power high-frequency radio waves with high efficiency. Also, a power receiving device and a wireless power transmission device including a rectifier circuit having the diode 200 as a rectifier diode can convert low-power high-frequency radio waves with high efficiency.

[0037] However, since the width of the depletion layer 205 is determined by the metal constituting the third electrode E3, the semiconductor constituting the semiconductor region 202, and the impurity concentration thereof, it may be difficult to design the width of the depletion layer 205 in the zero bias state shown in Figure 7 to match the width that blocks the current path of the semiconductor region 202.

[0038] Therefore, in the diode 200 of this embodiment, the third electrode E3 has a solid-phase diffusion region 204, and the desired diode characteristics can be obtained by controlling the depth at which this solid-phase diffusion region 204 is formed. As an example, in a zero-bias state, no current flows between the anode electrode A and the cathode electrode C, or only a current of less than 10 μA flows, at which point the current path is considered to be blocked. When a positive potential exceeding the voltage in the zero-bias state is applied to the anode electrode A, the width of the depletion layer 205 narrows, and a current path is formed. The solid-phase diffusion region 204 is disposed at a depth at which the depletion layer 205 is formed.

[0039] Note that if the impurity concentration of the semiconductor region 202 changes, the width of the depletion layer 205 formed in a zero bias state will change. The thickness of the semiconductor region 202 is set to obtain desired diode characteristics. Therefore, the depth at which the solid-phase diffusion region 204 is formed is set according to the impurity concentration and thickness of the semiconductor region 202. The solid-phase diffusion region 204 can be formed with good controllability to reach a predetermined depth by setting the thickness of platinum deposited directly on the semiconductor region 202 to a predetermined film thickness.

[0040] The current-voltage characteristics of the diode of this embodiment are similar to those of the diode of the first embodiment, in that the on-voltage is very low.

[0041] The diode of this embodiment is not limited to the configurations shown in Figures 6 to 8 as long as the semiconductor region 202 into which platinum constituting the third electrode E3 undergoes solid-phase diffusion includes a semiconductor region containing AlGaAs and / or GaAs that forms a Schottky junction. For example, the semiconductor region 202 can be formed by an epitaxially grown layer or a semiconductor region formed by vapor phase diffusion. Alternatively, an InGaP layer may be disposed on the exposed surface of the semiconductor region 202 as a semiconductor region with a low surface state density to suppress the formation of a surface depletion layer.

[0042] (Embodiment 3) Next, an embodiment of a rectifier circuit according to another aspect of the present invention will be described. FIG. 9 is a diagram illustrating one embodiment (Embodiment 3) of a rectifier circuit according to another aspect of the present invention. Rectifier circuit 300 shown in FIG. 9 is composed of input terminal 310 for receiving high-frequency radio waves, output terminal 320 for outputting DC power, ground terminal 330, rectifier section 340, and smoothing section 350. Rectifier section 340 is composed of capacitor 341 and diodes 342 and 343, and smoothing section 350 is composed of capacitor 351. In particular, in rectifier circuit 300 of this embodiment, diodes 342 and 343, which serve as rectifier diodes constituting rectifier section 340, are composed of the diodes according to one aspect of the present invention described above.

[0043] In the rectifier circuit 300 of this embodiment, the rectifier diode is, as an example, the diode 100 described in the first embodiment. As described above, the diode 100 has an on-voltage of approximately 0.025 V (almost 0 V), making it a diode with a very low on-voltage. Therefore, even when the power of the high-frequency radio waves input from the input terminal 310 of the rectifier circuit 300 is low, the high-frequency radio waves can be rectified in the rectifier unit 340, and the DC power smoothed by the smoothing unit 350 can be output from the output terminal 320.

[0044] Fig. 10 is a diagram showing the relationship between input power and rectification efficiency of the rectifier circuit of this embodiment. In Fig. 10, the solid line shows the characteristics of rectifier circuit 300 of this embodiment, and the dashed line shows the characteristics of a comparative rectifier circuit in which diodes 342 and 343 are configured as Schottky barrier diodes made of silicon semiconductor with an on-voltage of 0.3 V. As shown by the solid line in Fig. 10, rectifier circuit 300 of this embodiment has high rectification efficiency, and it can be seen that this rectification efficiency is particularly high when the power of the input high-frequency radio waves is low.

[0045] The diodes 342 and 343 of this embodiment can be configured with the diode 200 described in the second embodiment above, instead of the diode 100 described in the first embodiment above. Furthermore, the diodes 342 and 343 of this embodiment can be configured such that the semiconductor region in which platinum constituting the third electrode undergoes solid-phase diffusion includes a semiconductor layer containing AlGaAs and / or GaAs that forms a Schottky junction. In these cases, the diodes 342 and 343 are diodes with a very low on-state voltage. Therefore, even when the power of the input high-frequency radio waves is low, the DC power rectified by the rectifier 340 and smoothed by the smoothing unit 350 can be output from the output terminal 320, resulting in a rectifier circuit with high rectification efficiency, particularly when the input power is low.

[0046] The rectifier circuit 300 is not limited to the configuration shown in Fig. 9 as long as it has a rectifier diode. For example, it can be a single-shunt rectifier circuit or a diode bridge rectifier circuit. Furthermore, instead of being configured with a single rectifier diode, the rectifier diode can be configured with multiple diodes connected in series.

[0047] (Embodiment 4) Next, an embodiment of a power receiving device according to yet another aspect of the present invention will be described. Fig. 11 is a diagram illustrating one embodiment (Embodiment 4) of a power receiving device according to yet another aspect of the present invention. The power receiving device 400 shown in Fig. 11 includes an antenna 410 that receives high-frequency radio waves and a rectifier circuit 420 that rectifies the input high-frequency radio waves and outputs DC power, and the DC power is output from an output terminal 430 to a load. The rectifier circuit 420 of this embodiment is configured with the rectifier circuit according to another aspect of the present invention described above, and the rectifier diodes that form the rectifier section of this rectifier circuit are configured with diodes according to one aspect of the present invention.

[0048] The antenna 410 is an antenna that can receive high frequency radio waves, and can be configured as, for example, a patch antenna, a dipole antenna, or the like.

[0049] Rectifier circuit 420 receives high frequency radio waves received by antenna 410, rectifies the received radio waves, and outputs DC power from output terminal 430. Rectifier circuit 420 may have the configuration shown in Fig. 9 described in the third embodiment above, as an example, and the diode constituting rectifier unit 340 may be, for example, either diode 100 described in the first embodiment above or diode 200 described in the second embodiment above.

[0050] The DC power output from the output terminal 430 is output to a load such as an electronic device or a storage battery that can receive DC power.

[0051] In the power receiving device 400 of this embodiment, the rectifier diodes constituting the rectifier circuit 420 that inputs high-frequency radio waves received by the antenna 410, rectifies the radio waves, and outputs DC power are configured with diodes with low on-state voltage, so that when low-power high-frequency radio waves are input, the rectifier circuit 420 has high rectification efficiency. As a result, the power receiving device 400 of this embodiment has high conversion efficiency, and the conversion efficiency is particularly high when the power of the input high-frequency radio waves is low.

[0052] (Embodiment 5) Next, another embodiment of a power receiving device according to the present invention will be described. Fig. 12 is a diagram illustrating another embodiment (embodiment 5) of a power receiving device according to the present invention. Power receiving device 500 shown in Fig. 12 is composed of antenna 510 that receives high-frequency radio waves, and two rectifier circuits 520 and 530 that rectify the input high-frequency radio waves and output DC power, with different rectifier efficiency characteristics. The outputs of the two rectifier circuits 520 and 530 are combined, and DC power is output from output terminal 540 to a load.

[0053] Antenna 510 is an antenna that can receive high frequency radio waves, and can be configured as, for example, a patch antenna, a dipole antenna, or the like.

[0054] Rectifier circuit 520 (corresponding to the first rectifier circuit) is configured, for example, with rectifier circuit 420 described in the above-mentioned fourth embodiment, and like rectifier circuit 420, receives high-frequency radio waves received by antenna 510 and outputs rectified DC power from output terminal 540. Rectifier circuit 520 has, for example, the configuration shown in Fig. 9 described in the above-mentioned third embodiment, and diodes 342 and 343 constituting rectifier unit 340 can be configured, for example, with either diode 100 described in the above-mentioned first embodiment or diode 200 described in the above-mentioned second embodiment.

[0055] On the other hand, rectifier circuit 530 (corresponding to a second rectifier circuit) is configured to have rectification efficiency characteristics different from those of rectifier circuit 520. Rectifier circuit 530 is configured to have characteristics in which rectification efficiency is lower at low power and higher at high power compared to rectifier circuit 520. With this configuration, when the power of the high-frequency radio waves input to power receiving device 500 is low, DC power is output from rectifier circuit 520, and when the power of the input high-frequency radio waves increases, DC power is output from rectifier circuits 520 and 530.

[0056] The configuration of rectifier circuit 530 is not particularly limited, but by using a configuration similar to that of rectifier circuit 520, rectifier circuits 520 and 530 can be easily formed. As an example, rectifier circuit 530 can be configured, like the rectifier circuit shown in FIG. 9, with an input terminal for receiving high-frequency radio waves, an output terminal for outputting DC power, a ground terminal, a rectifier section, and a smoothing section. The rectifier section is configured with a capacitor and two diodes, and the smoothing section is configured with a capacitor. Here, in rectifier circuit 530 of this embodiment, the two rectifier diodes of the rectifier section are configured with diodes having a higher on-voltage than the two rectifier diodes of the rectifier section of rectifier circuit 520, thereby making the rectification efficiency of rectifier circuit 530 different from that of rectifier circuit 520.

[0057] FIG. 13 is a cross-sectional schematic diagram of a diode 600, an example of a rectifier diode in the rectifier circuit 530 of this embodiment, in which the voltage applied to the anode electrode A and the voltage applied to the cathode electrode C are in a zero bias state. As shown in FIG. 13 , the diode 600 includes a substrate 601 made of, for example, semi-insulating GaAs, on which a buffer layer 602, a channel layer 603 made of undoped InGaAs, a carrier supply layer 604 made of highly doped n-type AlGaAs, and a contact layer 605 made of highly doped n-type GaAs are disposed. The diode 600 is formed in a semiconductor region surrounded by an isolation region 608. A first electrode E1 and a second electrode E2 are disposed on each contact layer 605, forming an ohmic junction with the contact layer 605. A third electrode E3 is disposed on the carrier supply layer 604, forming a Schottky junction with the carrier supply layer 604. The third electrode E3 includes a solid-phase diffusion region 606 formed by diffusing platinum into the carrier supply layer 604. Here, the depth at which the solid phase diffusion region 606 is formed is deeper than the depth at which the solid phase diffusion region 106 of the diode 100 shown in FIG.

[0058] 13, in the diode 600 serving as the rectifier diode of the rectifier circuit 530 configured in this manner, a depletion layer 609 is formed in a zero bias state so as to block the current path between the anode electrode A and the cathode electrode C below the solid-phase diffusion region 606, and the depletion layer 609 extends widely toward the substrate 601. The depth at which the depletion layer 609 of the diode 600 is formed is deeper than the depth at which the depletion layer 109 of the diode 100 shown in FIG. 3 is formed. In this state, no current flows between the anode electrode A and the cathode electrode C.

[0059] When a positive voltage exceeding the voltage (0 V) applied under zero bias conditions is applied to the anode electrode A, the width of the depletion layer 609 formed below the solid-phase diffusion region 606 narrows. However, because the solid-phase diffusion region 606 is formed deep, the current path remains blocked and no current flows between the anode electrode A and the cathode electrode C. When a positive voltage is further applied to the anode electrode A, two-dimensional electron gas is generated, forming a current path consisting of the two-dimensional electron gas layer 607, and current begins to flow between the anode electrode A and the cathode electrode C. When the voltage applied to the anode electrode A is further increased, the concentration of the two-dimensional electron gas in the two-dimensional electron gas layer 607 increases, increasing the current flowing between the anode electrode A and the cathode electrode C, and achieving diode characteristics. In this way, the on-voltage at which current begins to flow between the anode electrode A and the cathode electrode C can be set to a voltage greater than 0 V.

[0060] The rectifier diode of the rectifier circuit 520 may be configured, for example, as the diode 200 shown in FIG. 6, and the rectifier diode of the rectifier circuit 530 may be configured to form the solid-phase diffusion region 204 at a greater depth than the diode 200.

[0061] Diodes with different on-state voltages can be constructed by combining diodes with different structures, but as explained above, it is preferable to combine diodes with solid-phase diffusion regions formed at different depths, because this shortens the manufacturing process when simultaneously forming diodes with different on-state voltages simply by changing the thickness of the platinum formed to form the solid-phase diffusion region. Of course, the depth of solid-phase diffusion region 606, the impurity concentration of carrier supply layer 604, the gate width, etc. may be appropriately set to achieve the desired rectification characteristics of rectifier circuit 530.

[0062] The power receiving device 500 of this embodiment is capable of rectifying high-frequency radio waves received by the antenna 510 using rectifier circuits 520 and 530 with different rectification characteristics, and therefore, by combining rectifier circuits with desired rectification characteristics, it is possible to configure a power receiving device 500 with desired conversion characteristics.

[0063] (Embodiment 6) Next, an embodiment of a wireless power transmission device according to yet another aspect of the present invention will be described. Fig. 14 is an explanatory diagram of an embodiment (Embodiment 6) of a wireless power transmission device according to yet another aspect of the present invention. The wireless power transmission device 700 shown in Fig. 14 is composed of a power transmitting device 710 and a power receiving device 720. The power transmitting device 710 is composed of an antenna 711 that transmits high-frequency radio waves and a power transmitting circuit 712 that generates high-frequency radio waves. The power receiving device 720 is composed of an antenna 721 that receives high-frequency radio waves and a rectifying circuit 722 that rectifies the input high-frequency radio waves and outputs DC power. The DC power is output from an output terminal 723 to a load. The power receiving device 720 is composed of the power receiving device according to yet another aspect of the present invention described above. The rectifying circuit of this power receiving device is composed of a rectifying circuit according to another aspect of the present invention. In this rectifying circuit, the diodes constituting the rectifying section are composed of diodes according to one aspect of the present invention.

[0064] The power transmitting device 710 converts DC power into high-frequency power in, for example, a power transmitting circuit 712, amplifies the power, and outputs the high-frequency power from an antenna 711. The antenna 711 is an antenna that can transmit high-frequency radio waves, and can be configured, for example, as a patch antenna, a dipole antenna, or the like.

[0065] In the power receiving device 720, the rectifier circuit 722 receives high-frequency radio waves via an antenna 721, rectifies the radio waves, and outputs DC power. The rectifier diodes in the rectifier circuit 722 have low on-state voltages, so that when a low-power high-frequency radio wave is input, the rectifier circuit 722 has high rectification efficiency. As a result, the power receiving device 720 can be configured with high conversion efficiency.

[0066] As a result, it is possible to configure a wireless power transmission device 700 with high conversion efficiency.

[0067] In addition, the power receiving device 720 can also rectify the high-frequency radio waves received by the antenna 510 using multiple rectifier circuits with different rectification characteristics, and by combining rectifier circuits with the desired rectification characteristics, it is possible to configure a power receiving device 720 with the desired conversion characteristics.

[0068] As a result, it is possible to configure a wireless power transmission device 700 with desired conversion characteristics.

[0069] (summary) (1) One embodiment of a diode according to the present invention includes a semiconductor region in which a current path is formed, first and second electrodes spaced apart from each other and forming an ohmic junction with the semiconductor region, and a third electrode disposed between the first and second electrodes, electrically connected to the first electrode, and forming a Schottky junction with the semiconductor region, the first and third electrodes serving as anode electrodes and the second electrode serving as a cathode electrode, and the semiconductor region includes a region made of AlGaAs and / or GaAs that forms a Schottky junction with the third electrode. the third electrode has a solid-phase diffusion region in which platinum has been solid-phase diffused into the region composed of AlGaAs and / or GaAs, and the solid-phase diffusion region has a depth at which the depletion layer is disposed such that, when a voltage applied to the anode electrode is in a zero bias state, the current path is depleted by a depletion layer formed in the semiconductor region below the solid-phase diffusion region, and the current path is blocked, and when a positive voltage exceeding the voltage applied to the anode electrode in a zero bias state is applied to the anode electrode, the width of the depletion layer narrows and the current path is formed.

[0070] The diode (1) above has a low on-state voltage and is capable of rectifying low-power high-frequency radio waves.

[0071] (2) According to another embodiment, in the diode of (1) above, the semiconductor region has a carrier supply layer and a channel layer, and the current path includes a two-dimensional electron gas layer formed in the semiconductor region.

[0072] In the diode of (2) above, the carriers become two-dimensional electron gas, the series resistance of the current path is low, the on-voltage is low, and rectification of low-power high-frequency radio waves is possible.

[0073] (3) Another embodiment of the rectifier circuit of the present invention is a rectifier circuit that converts input high-frequency radio waves into DC power and outputs the DC power, the rectifier circuit having a rectifier diode that converts the high-frequency radio waves into DC power, the rectifier diode being the diode described in (1) or (2) above.

[0074] According to the rectifier circuit of (3) above, the rectifier diode is a diode with a low on-voltage, and a rectifier circuit with high rectification efficiency can be configured.

[0075] (4) Another embodiment of the power receiving device of the present invention is a power receiving device including an antenna for receiving high-frequency radio waves and a rectifier circuit for inputting the high-frequency radio waves, converting the radio waves into DC power, and outputting the DC power, wherein the rectifier circuit has a rectifier diode for converting the high-frequency radio waves into DC power, and the rectifier diode is the diode described in (1) or (2) above.

[0076] According to the power receiving device of (4) above, by including a rectifier circuit with high rectification efficiency, it is possible to configure a power receiving device with high conversion efficiency.

[0077] (5) According to another embodiment, in the power receiving device of (4) above, the rectifier circuit comprises a first rectifier circuit and a second rectifier circuit having different rectification efficiencies, and the rectifier diode of the first rectifier circuit is the diode of (1) or (2) above.

[0078] According to the power receiving device of (5) above, it is possible to rectify the input high frequency radio waves using rectifier circuits with different rectification characteristics, so that a power receiving device with desired conversion characteristics can be configured.

[0079] (6) According to another embodiment, in the power receiving device of (5) above, the rectifier diode of the second rectifier circuit includes a semiconductor region in which a current path is formed, and a first electrode and a second electrode spaced apart from each other and forming an ohmic junction with the semiconductor region, and a third electrode disposed between the first electrode and the second electrode, electrically connected to the first electrode, and forming a Schottky junction with the semiconductor region, the semiconductor region having a region made of AlGaAs and / or GaAs that forms a Schottky junction with the third electrode, and the third electrode having a solid-phase diffusion region in which platinum has been solid-phase diffused into the region made of AlGaAs and / or GaAs, and the diode has the first electrode and the third electrode as anode electrodes and the second electrode as cathode electrode.

[0080] According to the power receiving device of (6) above, when diodes with different on-voltages are formed simultaneously, the manufacturing process can be shortened.

[0081] (7) A wireless power transmission device including a power transmitting device having a power transmitting circuit that generates high-frequency radio waves and an antenna that transmits the high-frequency radio waves, and a power receiving device having an antenna that receives the high-frequency radio waves and a rectifying circuit that receives the high-frequency radio waves, converts them into DC power, and outputs the DC power, wherein the rectifying circuit has a rectifying diode that converts the high-frequency radio waves into DC power, and the rectifying diode is a diode described in (1) or (2) above.

[0082] According to the wireless power transmission device of (7) above, by including a rectifier circuit with high rectification efficiency, it is possible to configure a wireless power transmission device with high conversion efficiency.

[0083] (8) According to another embodiment, in the wireless power transmission device of (7) above, the rectifier circuit comprises a first rectifier circuit and a second rectifier circuit having different rectification efficiencies, and the rectifier diode of the first rectifier circuit is the diode of (1) or (2) above.

[0084] According to the wireless power transmission device of (8) above, it is possible to rectify the input high-frequency radio waves using rectifier circuits with different rectification characteristics, so that by combining rectifier circuits with desired rectification characteristics, it is possible to configure a wireless power transmission device with desired conversion characteristics. [Explanation of symbols]

[0085] 100, 200, 342, 343, 600 diodes 101, 201, 601 boards 102, 602 buffer layer 103, 603 channel layer 104, 604 Carrier supply layer 105, 203, 605 Contact layer 106, 204, 606 Solid-state diffusion region 107, 607 Two-dimensional electron gas layer 108, 608 isolation area 109, 205, 609 depletion layer 202 Semiconductor area 300, 420, 520, 530, 722 rectifier circuit 310 Input terminal 320, 430, 540, 723 output terminal 330 Ground terminal 340 Rectifier 341, 351 capacitors 350 smooth part 400, 500, 720 powered devices 410, 510, 711, 721 antennas 700 Wireless power transmission device 710 Power Transmission Equipment 712 Power Transmission Circuit E1 1st electrode E2 2nd electrode E3 3rd electrode A Anode electrode C. Cathode electrode

Claims

1. a semiconductor region in which a current path is formed; a first electrode and a second electrode that are spaced apart from each other and that form an ohmic junction with the semiconductor region; a third electrode disposed between the first electrode and the second electrode, electrically connected to the first electrode, and forming a Schottky junction with the semiconductor region; a diode in which the first electrode and the third electrode are anode electrodes and the second electrode is a cathode electrode, the semiconductor region has a region made of AlGaAs and / or GaAs that forms a Schottky junction with the third electrode, the third electrode has a solid-phase diffusion region in which platinum is solid-phase diffused into the region made of AlGaAs and / or GaAs, The solid phase diffusion region is When a voltage applied to the anode electrode is in a zero bias state, the current path is depleted by a depletion layer formed in the semiconductor region below the solid-phase diffusion region, and the current path is blocked; and When a positive voltage exceeding the voltage applied in a zero bias state is applied to the anode electrode, the width of the depletion layer narrows and the current path is formed. The depletion layer has a depth diode.

2. the semiconductor region has a carrier supply layer and a channel layer, the current path includes a two-dimensional electron gas layer formed in the semiconductor region; The diode of claim 1.

3. A rectifier circuit that converts input high-frequency radio waves into DC power and outputs it, the rectifier circuit has a rectifier diode that converts the high-frequency radio wave into DC power, The rectifying diode is a diode according to claim 1 or 2. rectifier circuit.

4. A power receiving device including an antenna for receiving high frequency radio waves and a rectifier circuit for receiving the high frequency radio waves, converting the received radio waves into DC power, and outputting the DC power, the rectifier circuit has a rectifier diode that converts the high-frequency radio wave into DC power, The rectifying diode is a diode according to claim 1 or 2. Power receiving device.

5. The rectifier circuit includes a first rectifier circuit and a second rectifier circuit having different rectification efficiencies, The rectifier diode of the first rectifier circuit is the diode according to claim 1 or 2. The power receiving device according to claim 4.

6. The rectifier diode of the second rectifier circuit is a semiconductor region in which a current path is formed; a first electrode and a second electrode that are spaced apart from each other and that form an ohmic junction with the semiconductor region; a third electrode disposed between the first electrode and the second electrode, electrically connected to the first electrode, and forming a Schottky junction with the semiconductor region; the semiconductor region has a region made of AlGaAs and / or GaAs that forms a Schottky junction with the third electrode, the third electrode has a solid-phase diffusion region in which platinum is solid-phase diffused into the region made of AlGaAs and / or GaAs, a diode in which the first electrode and the third electrode serve as anode electrodes and the second electrode serves as a cathode electrode; The power receiving device according to claim 5 .

7. A wireless power transmission device including a power transmitting device having a power transmitting circuit that generates high-frequency radio waves and an antenna that transmits the high-frequency radio waves, and a power receiving device having an antenna that receives the high-frequency radio waves and a rectifier circuit that receives the high-frequency radio waves, converts the received high-frequency radio waves into DC power, and outputs the DC power, the rectifier circuit has a rectifier diode that converts the high-frequency radio wave into DC power, The rectifying diode is a diode according to claim 1 or 2. Wireless power transmission device.

8. The rectifier circuit includes a first rectifier circuit and a second rectifier circuit having different rectification efficiencies, The rectifier diode of the first rectifier circuit is the diode according to claim 1 or 2. The wireless power transmission device according to claim 7.

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