Diode, rectification circuit, power reception device, and wireless power transmission device

Abstract

Provided is a diode (100) comprising: a semiconductor region in which a current path is formed; a first electrode (E1) and a second electrode (E2) that are disposed apart from each other and in ohmic contact with the semiconductor region; and a third electrode (E3) that is disposed between the first and second electrodes, electrically connected to the first electrode (E1), and in Schottky contact with the semiconductor region, wherein the first electrode (E1) and the third electrode (E3) serve as an anode electrode (A), the second electrode (E2) serves as a cathode electrode (C), the semiconductor region has a region comprising AlGaAs and / or GaAs and being in Schottky contact with the electrode (E3), and the third electrode (E3) has a solid-phase diffusion region (106) with a predetermined depth in which platinum is solid-phase diffused in the region comprising AlGaAs and / or GaAs. Also provided are a rectification circuit provided with the diode (100), and a power reception device and a wireless power transmission device that are provided with the rectification circuit.

Description

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

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

[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 a rectifier diode in a rectifier circuit significantly affects the radio frequency (RF) / direct current (DC) conversion efficiency, and therefore, Schottky barrier diodes are often used as rectifier diodes (see, for example, Patent Document 1).

[0004] Patent No. 6304520

[0005] In a wireless power transmission device using high-frequency radio waves, the high-frequency radio waves transmitted from the power transmitting device experience significant loss due to spatial propagation, and the power of the high-frequency radio waves received by the power receiving device is very low. 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 the band gap of compound semiconductors, and have an on-state voltage of approximately 0.3 V. Therefore, power receiving devices and the like equipped with rectifier circuits using Schottky barrier diodes made of silicon semiconductors as rectifier diodes have a relatively high conversion efficiency of low-power high-frequency radio 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 high-frequency radio 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 high-frequency radio waves, there is also the problem that they are limited in the conversion of even lower-power high-frequency radio waves.

[0008] Therefore, an object of the present disclosure 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.

[0009] A diode according to one aspect of the present disclosure comprises 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 diode having the first and third electrodes 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 at which the depletion layer is disposed such that, when the 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, blocking the current path, and when a positive potential 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 disclosure 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 diode.

[0011] Another aspect of the present disclosure 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 the power receiving device, wherein the rectifier circuit has a rectifier diode that converts the high-frequency radio waves into DC power, and the rectifier diode is configured with the diode.

[0012] A wireless power transmission device according to yet another aspect of the present disclosure is 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 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 diode.

[0013] The diode of the present disclosure 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 disclosure includes 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 disclosure, by including 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.

[0016] FIG. 1 is an explanatory diagram of an embodiment (Embodiment 1) of a diode according to one aspect of the present disclosure, being a planar schematic diagram of the diode. FIG. 2 is a cross-sectional schematic diagram of the diode taken along line X-X of FIG. 1. FIG. 3 is a diagram illustrating the operation of the diode according to Embodiment 1. FIG. 4 is a diagram illustrating the operation of the diode according to Embodiment 1. FIG. 5 is a diagram illustrating the current-voltage characteristics of the diode according to Embodiment 1. FIG. 6 is an explanatory diagram of another embodiment (Embodiment 2) of a diode according to one aspect of the present disclosure, being a cross-sectional schematic diagram of the diode. FIG. 7 is a diagram illustrating the operation of the diode according to Embodiment 2. FIG. 8 is a diagram illustrating the operation of the diode according to Embodiment 2. FIG. 9 is an explanatory diagram of an embodiment (Embodiment 3) of a rectifier circuit according to another aspect of the present disclosure. FIG. 10 is a diagram illustrating the relationship between input power and rectification efficiency of the rectifier circuit according to Embodiment 3. FIG. 11 is an explanatory diagram of an embodiment (Embodiment 4) of a power receiving device according to yet another aspect of the present disclosure. FIG. 12 is an explanatory diagram of another embodiment (Embodiment 5) of a power receiving device according to yet another aspect of the present disclosure. FIG. 13 is an explanatory diagram of a rectifier diode of a rectifier circuit constituting the power receiving device according to Embodiment 5. 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 disclosure.

[0017] Next, embodiments of the diode, rectifier circuit, power receiving device, and wireless power transmission device of the present disclosure will be described with reference to the drawings, but the present disclosure 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 disclosure. 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 one aspect of the present disclosure will be described. FIG. 1 is an explanatory diagram of one embodiment (Embodiment 1) of a diode according to one aspect of the present disclosure, and is a schematic plan view of the diode. FIG. 2 is a schematic cross-sectional view of the diode of FIG. 1 taken along line X-X. 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 disposed 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, forming an ohmic junction with the contact layer 105. The first electrode E1 and the second electrode E2 can be formed, for example, of a metal stack of AuGe / Ni / Au. A third electrode E3 is disposed on the carrier supply layer 104, forming 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, whereby platinum deposited directly on the carrier supply layer 104 diffuses 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 deposited directly 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 illustrating 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 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), blocking the current path between the anode electrode A and the cathode electrode C. In this state, the depth-wise width of the depletion layer 109 (hereinafter referred to as the "depletion layer width") is set to the narrowest width necessary to eliminate the two-dimensional electron gas and block the current path. In this state, no current flows between the anode electrode A and the cathode electrode C.

[0023] 4, 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. 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, the current flowing between the anode electrode A and the cathode electrode C increases, and diode characteristics can be obtained.

[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 FIG. 3 to match 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, and 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

[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, a non-doped AlGaAs layer having a decreasing Al composition toward the surface as a band gap reduction layer may be disposed on the carrier supply layer 104 made of AlGaAs, and a non-doped GaAs layer may be disposed on the non-doped 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 stacked 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] 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, resulting in a diode with an extremely low on-voltage.

[0029] 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 disclosure will be described. FIG. 6 is an explanatory diagram of another embodiment (Embodiment 2) of a diode according to the present disclosure, 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 X-X 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 whose upper surface 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 may 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 can be formed, for example, of 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. This 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, so that platinum, which is stacked directly on the semiconductor region 202, diffuses 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 desired diode characteristics, which will be described later, 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, 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] 8, 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, a current path is formed in the semiconductor region 202, and a 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 width of the depletion layer 205 further narrows, and the current flowing between the anode electrode A and the cathode electrode C increases, resulting in diode characteristics.

[0035] In this embodiment, too, 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 FIG. 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 it is considered that the current path is blocked, and 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 changes. 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 configuration shown in FIGS. 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 may be formed by an epitaxial growth 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 disclosure will be described. FIG. 9 is a diagram illustrating one embodiment (Embodiment 3) of a rectifier circuit according to another aspect of the present disclosure. Rectifier circuit 300 shown in FIG. 9 is configured with input terminal 310 for receiving high-frequency radio waves, output terminal 320 for outputting DC power, ground terminal 330, rectifier unit 340, and smoothing unit 350. Rectifier unit 340 is configured with capacitor 341 and diodes 342 and 343, and smoothing unit 350 is configured with capacitor 351. In particular, in rectifier circuit 300 of this embodiment, diodes 342 and 343, which serve as rectifier diodes constituting rectifier unit 340, are configured with the diodes according to one aspect of the present disclosure 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] 10 is a diagram showing the relationship between the input power and rectification efficiency of the rectifier circuit of this embodiment. In Fig. 10, the solid line shows the characteristics of the rectifier circuit 300 of this embodiment, and the dashed line shows the characteristics of a comparative example 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, the 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. 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 also have 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 another aspect of the present disclosure will be described. Fig. 11 is a diagram illustrating an embodiment (Embodiment 4) of a power receiving device according to another aspect of the present disclosure. 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 disclosure 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 disclosure.

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

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

[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, which 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 yet another aspect of the present disclosure will be described. Fig. 12 is a diagram illustrating another embodiment (Embodiment 5) of a power receiving device according to yet another aspect of the present disclosure. The power receiving device 500 shown in Fig. 12 is composed of an 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 the DC power is output from an output terminal 540 to a load.

[0053] The antenna 510 is an antenna capable of receiving 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, by 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, by 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 the 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 of lower rectification efficiency at low power and higher rectification efficiency 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 the rectifier circuit 530 is not particularly limited, but by using a configuration similar to that of the rectifier circuit 520, the rectifier circuits 520 and 530 can be easily formed. As an example, the 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 the 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 the rectifier circuit 520, thereby making the rectification efficiency of the rectifier circuit 530 different from that of the rectifier circuit 520.

[0057] FIG. 13 is a cross-sectional schematic diagram of a diode 600, an example of a rectifier diode of 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. Furthermore, 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 has 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. 3, which is an example of the diode of the rectifier circuit 520, is formed.

[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, thereby 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 so that the depth at which the solid-phase diffusion region 204 is formed is deeper than that of the diode 200.

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

[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 the desired rectification characteristics, it is possible to configure a power receiving device 500 with the desired conversion characteristics.

[0063] Sixth Embodiment Next, an embodiment of a wireless power transmission device according to yet another aspect of the present disclosure will be described. Fig. 14 is an explanatory diagram of an embodiment (sixth embodiment) of a wireless power transmission device according to yet another aspect of the present disclosure. A wireless power transmission device 700 shown in Fig. 14 includes a power transmitting device 710 and a power receiving device 720. The power transmitting device 710 includes 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 includes an antenna 721 that receives high-frequency radio waves and a rectifier 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 includes the power receiving device according to yet another aspect of the present disclosure described above. The rectifier circuit of this power receiving device includes a rectifier circuit according to another aspect of the present disclosure. The rectifier circuit includes a diode that constitutes a rectifier section and is a diode according to one aspect of the present disclosure.

[0064] The power transmitting device 710 converts DC power into high-frequency power, for example, in a power transmitting circuit 712, amplifies the power, and outputs high-frequency radio waves 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 the 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 low-power high-frequency radio waves are 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] 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 one aspect of the present disclosure includes 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 first electrode and the third electrode 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 made 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 potential 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 of (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 a rectifier circuit of the present disclosure 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, and the rectifier diode is 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-state voltage, and a rectifier circuit with high rectification efficiency can be configured.

[0075] (4) Another embodiment of a power receiving device according to the present disclosure 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. The rectifier circuit has a rectifier diode for converting the high-frequency radio waves into DC power. 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 yet another embodiment, in the power receiving device of (5), 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 and forming a Schottky junction with the third electrode, 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 the 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. Therefore, by combining rectifier circuits with the desired rectification characteristics, it is possible to configure a wireless power transmission device with the desired conversion characteristics.

[0085] 100, 200, 342, 343, 600 Diode 101, 201, 601 Substrate 102, 602 Buffer layer 103, 603 Channel layer 104, 604 Carrier supply layer 105, 203, 605 Contact layer 106, 204, 606 Solid phase diffusion region 107, 607 Two-dimensional electron gas layer 108, 608 Isolation region 109, 205, 609 Depletion layer 202 Semiconductor region 300, 420, 520, 530, 722 Rectifier circuit 310 Input terminal 320, 430, 540, 723 Output terminal 330 Ground terminal 340 Rectifier section 341, 351 Capacitor 350 Smoothing section 400, 500, 720 Power receiving device 410, 510, 711, 721 Antenna 700 Wireless power transmission device 710 Power transmitting device 712 Power transmitting circuit E1 First electrode E2 Second electrode E3 Third electrode A Anode electrode C Cathode electrode

Claims

1. A diode comprising: a semiconductor region in which a current path is formed; first and second electrodes spaced apart from each other and making 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 making a Schottky junction with the semiconductor region; wherein the first and third electrodes serve as anode electrodes and the second electrode serves as a cathode electrode, wherein the semiconductor region has a region made of AlGaAs and / or GaAs that makes a Schottky junction with the third electrode, and the third electrode has a solid-phase diffusion region in which platinum has been solid-phase diffused into the region made of AlGaAs and / or GaAs, and wherein, 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; a diode having a depth at which the depletion layer is disposed such that, 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.

2. The diode according to claim 1, wherein 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.

3. A rectifier circuit that converts input high frequency radio waves into DC power and outputs the DC power, said rectifier circuit having a rectifier diode that converts said high frequency radio waves into DC power, said rectifier diode being the diode defined in claim 1 or 2.

4. A power receiving device comprising 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 defined in claim 1 or 2.

5. The power receiving device according to claim 4, wherein the rectifier circuits include 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 according to claim 1 or 2.

6. The power receiving device according to claim 5, wherein the rectifier diode of the second rectifier circuit comprises: 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, wherein the semiconductor region has a region made of AlGaAs and / or GaAs that forms a Schottky junction with the third electrode, and the third electrode has a solid-phase diffusion region in which platinum has been solid-phase diffused into the region made of AlGaAs and / or GaAs, and wherein the rectifier diode is constituted by a diode with the first electrode and the third electrode as anode electrodes and the second electrode as cathode electrode.

7. 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 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 the diode defined in claim 1 or 2.

8. The wireless power transmission device according to claim 7, wherein the rectifier circuits include 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 according to claim 1 or 2.

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