JP4138673B2 - Diamond sensor - Google Patents

Description

  The present invention relates to a diamond sensor using a diamond thin film that detects short-wavelength light such as ultraviolet rays and ionizing radiation such as α-rays, β-rays, γ-rays, and X-rays without being affected by sunlight. The present invention relates to a diamond sensor using an oriented diamond thin film.

  With the development of science and technology, the opportunity to use light in the short wavelength region of 250 nm or less, which has been rarely used in the past, for industrial purposes is increasing. For example, in sterilization and ozone cleaning, light in the vicinity of 250 nm and shorter wavelengths is used. Further, in a microfabrication technique for manufacturing a next-generation LSI, light in a wavelength region shorter than 200 nm including an ArF laser has begun to be applied to lithography. Further, in recording media such as CDs and DVDs, the application of light having a wavelength shorter than the visible light region has been studied for the purpose of increasing the recording density. Furthermore, the use of soft X-rays emitted from synchrotron radiation facilities and particle beams such as α-rays is about to reach practical use. For this reason, the importance of means for accurately observing light in a short wavelength region of 250 nm or less is increasing.

  In general, when observing wavelengths shorter than visible light such as ultraviolet rays, it is desirable that light such as sunlight is insensitive because it causes malfunction. In addition, since light in the ultraviolet region has a high energy level, it has good reproducibility and high durability is required to perform stable observation over a long period of time.

  Therefore, recently, an ultraviolet sensor using a diamond thin film using a diamond thin film has been proposed (for example, see Non-Patent Documents 1 to 5). A diamond thin film is excellent in heat resistance and durability and has a property as a semiconductor having a wide band gap. Therefore, a low-cost and highly reliable sensor can be realized. This semiconductor sensor using diamond thin film has better durability than a sensor element that combines a wavelength filter with silicon having a narrow band gap, and is smaller than a sensor using a conventional phototube. There is an advantage that it can be reduced in weight and weight and a complicated circuit configuration is not required.

In the conventional diamond sensors described in Non-Patent Documents 1 to 5, a polycrystalline diamond thin film is used to reduce the manufacturing cost. As the structure, for example, there is a planar type in which a pair of electrodes is provided on the surface of a diamond thin film. FIG. 3 is a cross-sectional view schematically showing a conventional planar structure diamond sensor. In the conventional flat diamond sensor 100 shown in FIG. 3, a polycrystalline diamond thin film 102 is formed on an insulating substrate 101 such as Al ₂ O ₃ , for example. A pair of comb-shaped electrodes 103 is formed of gold or the like.

  In this conventional flat diamond sensor 100, when light is irradiated, electron-hole pairs are generated in the polycrystalline diamond thin film 101, and a bias voltage is applied between the comb-shaped electrodes 102, whereby the electron-positive pair is detected. A hole pair is collected by each electrode and detected as an electrical signal. The diamond sensor having such a configuration is generally called a photoconductor, and has a characteristic that it is insulative when it is not irradiated with light and changes to conductivity when irradiated with light.

  Since the diamond sensor 100 having the planar structure can use a high-quality diamond thin film having a low defect density and a low defect grain boundary, excellent accuracy can be obtained. However, in the diamond sensor 100, since the diamond thin film 102 as the detection layer is exposed in the region between the pair of comb electrodes 103 on the surface, when measuring light in a short wavelength region having a wavelength of 200 nm or less, The following problems arise.

  First, since light in a short wavelength region such as ultraviolet rays has a high energy level, there is a risk that organic substances present in the atmosphere are decomposed during irradiation and adhere to the sensor surface. When an organic substance or the like adheres to the sensor surface, the amount of incident light is reduced, and the detected signal intensity is reduced. Second, water may be adsorbed on the sensor surface, but when it receives strong ultraviolet rays, the water adsorbed on the sensor surface is dissociated and ionized. Such ions easily and slowly move on the sensor surface due to the electric field applied between the electrodes, causing a decrease in electrical resistance. In such a case, a temporal output change of several hundred seconds or more is observed at the start or end of ultraviolet irradiation, and an output corresponding to the light intensity cannot be obtained.

  In general, when a semiconductor material other than diamond such as silicon is used, a photodiode type sensor using a depletion layer formed by a Schottky junction or a pn junction is applied. This photodiode type sensor is less susceptible to disturbance because the depletion layer, which is the detection layer, is formed in the solid element, and it is easy to obtain good characteristics because a high electric field is applied only to the depletion layer efficiently. There are features. However, in the case of a diamond thin film, it is difficult to form a good Schottky junction or pn junction, so this configuration cannot be applied.

  In addition, there is a method of covering the sensor surface with silica, alumina, etc. in order to eliminate the influence on the sensor surface from the outside, but this method may reduce the durability, which is a characteristic of diamond, so it is not practical. Absent.

  Furthermore, a diamond sensor having a vertical structure in which an electrode is provided on the surface of a polycrystalline diamond thin film formed on a conductive substrate has been reported. FIG. 4 is a cross-sectional view schematically showing a conventional diamond sensor having a vertical structure. As shown in FIG. 4, in a conventional vertical diamond sensor 104, for example, a polycrystalline diamond thin film 102 is formed on a conductive substrate 105 such as low-resistance silicon. An electrode 106 having a thickness of about 200 mm is formed of gold or the like so as to cover it. In the vertical diamond sensor 104, a bias voltage is applied between the conductive substrate 105 and the electrode 106.

  This vertical diamond sensor 104 has a relatively small influence when organic substances, water, and the like are adsorbed on the sensor surface. However, when the polycrystalline diamond thin film 102 is formed by the vapor phase synthesis method, a high-density crystal grain boundary is generated in the vicinity of the substrate 105, so that the density of crystal defects becomes high and good characteristics cannot be obtained. There is a point. Further, it is possible to reduce crystal defects by increasing the thickness of the diamond film and polishing the back side thereof, but this method is enormously expensive and difficult to apply to a sensor for mass production.

  On the other hand, the present inventors have proposed a method of avoiding high-density crystal defects and crystal grain boundaries that occur at the initial stage of diamond growth, that is, near the interface between the substrate and the diamond film (see Patent Document 1). FIG. 5 is a cross-sectional view schematically showing the diamond element described in Patent Document 1. As shown in FIG. As shown in FIG. 5, in the method of manufacturing a diamond film described in Patent Document 1, a first diamond film 112 is formed on a substrate 111, and a metal film 114 having a plurality of holes 113 is formed thereon. After the film formation, the second diamond layer 115 is formed to prevent crystal defects and crystal grain boundaries from being generated in the second diamond layer 115. In FIG. 5, the vertical lines in the diamond layers 112 and 115 indicate the grain boundaries.

JP 2001-233695 A S. SM. Chan, 3 others, “UV Photodetectors from Thin Film Diamond”, “Phys. Stat. Sol. (A)”, 1996, Vol. 154, p. 445-454 R. D. McKeag, 1 other, “Diamond UV features: sensitivity and speed for visible blind applications”, “Diamond and Related Materials”, 1998, Vol. 7, p. 513-518 R. D. McKeag, two others, “Polycrystalline diamond photoconductive device with high UV-visible discrimination”, “Appl. Phys. Lett.”, 1995, Vol. 67, p. 2117-2119 Michael D. Whitfield, 5 others, “Diamond features for next generation 157-nm deep-UV photolithography tools”, “Diamond and Related Materials”, 2001, Vol. 10, p. 693-697 Tadayuki Kashiwagi and three others, “Ultraviolet detector using diamond”, “Summary of the 6th Diamond Symposium”, 1992, p. 88-89

  However, the conventional techniques described above have the following problems. When the diamond element 110 described in Patent Document 1 is applied to a diamond sensor, the metal film 114 provided between the first diamond layer 112 and the second diamond layer 115 tends to aggregate at a high temperature. There is. In addition, a plurality of holes 113 are formed in the metal film 113, but a complicated process is required to form such holes, and the metal film 114 is a second detection layer. In order to completely cover with the diamond layer 115, there is a problem that the film must be formed for a long time. Due to such problems, it is difficult to apply the diamond element 110 described in Patent Document 1 to a low-cost sensor for mass production.

  The present invention has been made in view of such problems, and an object of the present invention is to provide a diamond sensor that detects light in a short wavelength region such as ultraviolet rays that can be manufactured at low cost with few crystal defects.

  The diamond sensor according to the present invention includes a substrate, a first insulating diamond layer formed on the substrate, and a thickness greater than the first insulating diamond layer formed on the first insulating diamond layer. Comprises a thin conductive diamond layer, a second insulating diamond layer formed on the conductive diamond layer, and a surface electrode formed on the second insulating diamond layer, The carriers generated by the light incident on the insulating diamond layer 2 are collected by a bias voltage applied between the conductive diamond layer and the surface electrode, and an electric signal corresponding to the amount of the collected carriers. Is output.

  In the present invention, since a conductive diamond layer is provided between the first and second insulating diamond layers, crystal grain boundaries are formed in the second insulating diamond layer formed on the conductive diamond layer. It is possible to suppress the occurrence. Moreover, the density of crystal defects in the detection layer can be reduced by using the conductive diamond layer as an electrode and using the second insulating diamond layer as a detection layer to form a sensor having a vertical structure. . Further, the conductive diamond layer as an electrode does not require an opening or the like, and the manufacturing process can be simplified as compared with the conventional diamond element described in Patent Document 1, so that it can be manufactured at low cost. it can.

  The first and second insulating diamond layers and the conductive diamond layer are made of, for example, vapor-phase synthesized polycrystalline diamond. Thereby, the diamond layer excellent in controllability can be formed stably.

  Further, the second insulating diamond layer is preferably a highly oriented diamond layer having a (100) surface and crystal grains oriented in one direction with respect to the substrate. A highly oriented diamond layer is one in which the crystal grain growth direction and in-plane direction of polycrystalline diamond are both oriented in a fixed direction with respect to the substrate surface. The surface has a characteristic surface form in which flat (001) facets are arranged. For this reason, the crystal defect density in the vicinity of the surface of this film is smaller than that of a general polycrystalline film, and the carrier mobility is increased by an order of magnitude, so that the detection performance is improved as compared with the conventional diamond sensor.

  Further, the substrate may be conductive, the conductive diamond layer may be formed so as to cover the first insulating diamond layer, and the substrate and the conductive diamond layer may be electrically connected. . Thereby, when forming each diamond layer, since a photolithography process can be skipped, a sensor can be manufactured at low cost.

  Furthermore, the conductive diamond layer may be formed of, for example, p-type semiconductor diamond to which boron is added, and the thickness is preferably 0.05 to 2.00 μm. Thereby, sensor sensitivity improves.

  According to the present invention, the conductive diamond layer is provided between the first and second insulating diamond layers, the conductive diamond layer is used as an electrode, and the second insulating diamond layer is used as a detection layer. While the density of crystal defects inside can be reduced, it can be manufactured at low cost.

  Hereinafter, a diamond sensor according to an embodiment of the present invention will be specifically described with reference to the accompanying drawings. First, the diamond sensor according to the first embodiment of the present invention will be described. FIG. 1 is a cross-sectional view schematically showing the diamond sensor of the present embodiment. In FIG. 1, the vertical lines in the insulating diamond layers 2 and 4 and the conductive diamond layer 3 schematically show the crystal grain boundaries. As shown in FIG. 1, the diamond sensor 10 of the present embodiment includes, for example, a highly oriented first insulating diamond layer on a conductive substrate 1 such as a low resistance silicon substrate having a (001) surface. 2 is formed, and a conductive diamond layer 3 is formed so as to cover the first insulating diamond layer 2. The conductive diamond layer 3 is in contact with the substrate 1 and these are electrically connected. A highly oriented second insulating diamond layer 4 as a detection layer is formed on the conductive diamond layer 3, and a surface electrode 5 is formed on the surface of the second insulating diamond layer 4. Is formed.

  Further, this diamond element is mounted on a metal mount 6 such as a hermetic seal to become a diamond sensor 10. In this case, the surface electrode 5 and one terminal of the hermetic seal are connected by wire bonding or the like, and the substrate 1 and the other terminal of the hermetic seal are connected via the casing.

  In the diamond sensor 10 of the present embodiment, the entire surface of the first insulating diamond layer 2 is covered with the conductive diamond layer 3, but the present invention is not limited to this, and the conductive diamond layer is not limited thereto. 3 and the board | substrate 1 should contact, and these should just be electrically connected. The film thickness of the conductive diamond layer 3 may be a thickness that does not disturb the surface form of the first insulating diamond layer 2, and is preferably 0.05 to 2.00 μm, for example. . When the film thickness of the conductive diamond layer 3 is less than 0.05 μm, the collection efficiency is lowered. On the other hand, when the film thickness of the conductive diamond layer 3 exceeds 2.00 μm, the orientation of the second insulating diamond layer 4 formed thereon is lowered.

Further, the conductive diamond layer 3 can be formed of diamond made conductive by a known method such as ion implantation and doping. In particular, a p-type semiconductor synthesized by vapor phase using a gas containing B. It is preferably formed of diamond. In this case, the doping concentration of B is preferably 1 × 10 ¹⁹ cm ⁻³ or more in which the activation energy of B starts to decrease in order to reduce the resistance of the electrode portion and reduce the collection loss. The Mott transition concentration is more preferably 3 × 10 ²⁰ cm ⁻³ or more.

  The film thickness of the second insulating diamond layer 4 is not particularly limited, but is preferably 5 μm or more in order to reduce the leakage current when not irradiated. The film thickness of the second insulating diamond layer 4 has no upper limit, but in order to efficiently generate a high electric field in consideration of the light collection efficiency and applied voltage of the light to be measured, the light to be measured In the case of ultraviolet rays, soft X-rays, α rays, etc., the thickness of the second insulating diamond layer 4 is preferably 50 μm or less, more preferably 25 μm or less.

  Further, the surface electrode 5 can be formed of a general metal material such as gold, platinum, and aluminum. As the formation method, a vacuum deposition method, a sputtering method, an ion plating method, and a CVD (Chemical Vapor Deposition: A known method such as a chemical vapor deposition method can be applied. Further, as the shape of the surface electrode 5, an arbitrary shape such as a dot shape can be applied, but the shape should be such that light incident on the second insulating diamond layer 4 as a detection layer is not blocked as much as possible. It is desirable and, in particular, a fishbone type or a comb shape is preferable. For example, when measuring ultraviolet rays, it is preferable to use a comb-shaped electrode having a width of 1 to 50 μm and an electrode interval of 1 to 50 μm. The surface electrode 5 can also be formed of conductive diamond.

  In the diamond sensor 10 of this embodiment, since the conductive diamond layer 3 is formed between the first insulating diamond layer 2 and the second insulating diamond layer 4, as shown in FIG. In addition, it is possible to suppress the growth of crystal grain boundaries in the second insulating diamond layer. Then, by using the conductive diamond layer 3 as an electrode, the second insulating diamond layer 4 having a low crystal defect density can be used as a detection layer.

  In the diamond sensor 10 of the present embodiment, the first highly oriented insulating diamond layer 2 and the second highly oriented insulating diamond layer 4 are highly oriented diamond layers, and crystal grains of polycrystalline diamond are grown. Since both the direction and the in-plane direction are oriented in a fixed direction with respect to the substrate surface, the crystal defect density in the vicinity of the surface is smaller than that of a general polycrystalline film, and the carrier mobility is large. For this reason, the detection performance is superior to the conventional diamond sensor.

  Further, since the conductive diamond layer 3 of the diamond sensor 10 of the present embodiment does not need to be provided with an opening unlike the metal part of the diamond element described in Patent Document 1, the conductive diamond layer 3 is used as an electrode. Can be applied efficiently, and the manufacturing process can be simplified as compared with the diamond element described in Patent Document 1, so that the manufacturing cost can be reduced.

  Next, a method for manufacturing the diamond sensor 10 of the present embodiment will be described. Here, a method of forming a diamond layer by a CVD method will be described as an example. First, the low resistance silicon substrate 1 having a (001) surface is exposed to a mixed plasma of methane and hydrogen to carbonize the surface. Subsequently, a bias is applied to form diamond nuclei in an epitaxial relationship with the substrate 1 on the surface of the substrate 1. Thereafter, the application of the bias is stopped, and a mixed gas of methane and hydrogen is used as the atmospheric gas, and a diamond film is formed, for example, for 12 hours under the condition that the (100) plane is preferentially formed. As a result, a first highly-oriented insulating diamond film 2 having a (100) surface and crystal grains arranged in a certain direction is formed on the substrate 1 to a thickness of about 10 μm.

  Thereafter, diborane is added to the atmospheric gas as a doping gas, and a diamond film is formed, for example, for 2 hours to form the conductive diamond layer 3 on the first highly oriented insulating diamond film 2. The conductive diamond layer 3 is thinner than the first highly oriented insulating diamond film 2 and is about 0.05 to 2.00 μm, and its surface is a (100) plane. Next, a diamond film is formed, for example, for 5 to 12 hours under the condition that the (100) plane is preferentially formed by using an atmosphere gas as a mixed gas of methane and hydrogen. As a result, a second highly-oriented insulating diamond film 4 having a (100) surface and crystal grains arranged in a certain direction is formed on the conductive diamond layer 3 to a thickness of about 4 to 30 μm. Further, the particle size on the (100) plane is, for example, 3 to 50 μm, and even if the conductive diamond layer 3 is provided, the diamond surface form hardly changes.

  Next, after removing carbon components other than diamond adhering to the surface by washing with dichromic acid, rinsing with sulfuric acid and further washing with pure water. Thereafter, a predetermined electrode shape is patterned on the surface of the second highly oriented insulating diamond film 4 by photolithography, and, for example, platinum or the like is sputtered by a magnetron sputtering method or the like, and then lifted off to form the surface electrode 5.

  Next, the board | substrate 1 is cut | disconnected in chip shape, and each element cut out is fixed on a hermetic seal by making the surface in which the surface electrode 5 is formed into an upper surface. At this time, the surface electrode 5 and one terminal of the hermetic seal are wire-bonded with a gold wire to form the diamond sensor 10. The conductive diamond layer 3 is connected to the other terminal of the hermetic seal via the substrate 1 and the housing of the hermetic seal.

  As described above, the CVD method using plasma has excellent controllability of the orientation direction of crystal grains, and can synthesize polycrystalline diamond stably at low cost. A diamond sensor can be manufactured at low cost by gas phase synthesis of the diamond layer. However, the method of forming each diamond layer of the diamond sensor 10 of the present embodiment is not limited to the above-described CVD method, and various known methods can be applied.

  Next, the operation of the diamond sensor of the present embodiment configured as described above will be described. In the diamond sensor 10 of the present embodiment, the second highly oriented insulating diamond layer 4 serves as a detection layer, and a bias voltage is applied between the surface electrode 5 and the conductive diamond layer 3. Then, when light having an energy level higher than the band gap of diamond or particle beams having an ionizing action such as α rays, β rays, and γ rays are incident on the second highly oriented insulating diamond layer 4, Carriers (electrons and holes) are generated in the highly oriented insulating diamond layer 4. The carriers move due to the electric field generated by the bias voltage applied between the surface electrode 5 and the conductive diamond layer 3, are collected by the surface electrode 5 or the conductive diamond layer 3, and output as an electric signal. .

  Hereinafter, the effect of the Example of this invention is demonstrated compared with the comparative example which remove | deviates from the scope of the present invention. First, the vertical insulating diamond sensor of Examples 1 to 5 was fabricated by changing the film thickness of the second insulating diamond layer, and using the other configurations in the same manner as in the previous embodiment. At that time, a pair of comb-shaped electrodes were formed as surface electrodes, and both of the pair of comb-shaped electrodes were connected to one terminal of a hermetic seal (TO-5 type) to form electrodes having the same potential.

  As Comparative Example 1, the structure of the element is the same as in Example 1 described above, and one of the pair of comb-shaped electrodes is used as one terminal of a hermetic seal (TO-5 type) and the other is used as a hermetic seal. A diamond sensor having a planar structure was manufactured by wire bonding to the other terminal of each of the terminals using a gold wire. Further, as Comparative Example 2, after forming an insulating diamond film on a substrate for 12 hours to form an insulating diamond film, a pair of comb-shaped electrodes is formed on the surface, and a conductive diamond layer and a second insulating diamond are formed. An element without a layer was produced. Then, one of the pair of comb electrodes of the element is wire-bonded to one terminal of the hermetic seal (TO-5 type) and the other to the other terminal of the hermetic seal with a gold wire, A diamond sensor having a planar structure was obtained. Furthermore, as Comparative Example 3, a vertical structure in which a diamond element having the same configuration as that of Comparative Example 2 is manufactured, a pair of comb electrodes are short-circuited, and a bias voltage is applied between the substrate and the surface electrode. A diamond sensor was prepared.

The diamond sensors of Examples 1 to 5 and Comparative Examples 1 to 3 were placed in a measurement box where no external light was incident, and the dark current when a bias voltage was applied was measured with a picoammeter. Next, the response characteristics to the ultraviolet rays of the diamond sensors of Examples 1 to 5 and Comparative Examples 1 to 3 were evaluated. FIG. 2 is a block diagram showing the evaluation method. As the irradiation light source 12, a deuterium (L ₂ D ₂ ) lamp (model: L7293) manufactured by Hamamatsu Photonics was used. In the measurement, a bias voltage of 15 V was applied between the two electrodes of each diamond sensor 14 in the atmosphere, and the current obtained at the time of light irradiation was amplified by the amplifier 15 and then measured by the digital multimeter 16 as a voltage value. The evaluation was performed by irradiating the sensor with ultraviolet rays 13 for 10 minutes with the irradiation light intensity kept constant, blocking the ultraviolet rays 13, and measuring the time (time constant) until the value decreased to (1 / e). The above results are summarized in Table 1 below.

  As shown in Table 1, all of the sensors of Examples 1 to 5 and Comparative Examples 1 to 3 had practically sufficiently low leakage current. In particular, a sensor having a thickness of the second insulating diamond layer of 5 μm or more showed good characteristics. Further, the time constants of the sensors of Examples 1 to 5 were significantly reduced as compared with the sensor of Comparative Example 1, and the time response was improved. Furthermore, the sensors of Examples 1 to 5 had higher sensitivity than the conventional sensor of Comparative Example 2. This is presumably because the electron-hole pairs excited by the ultraviolet rays incident on the second insulating diamond layer as the detection layer can be efficiently captured. On the other hand, the sensor of Comparative Example 1 had good sensor characteristics, but the time constant was equivalent to that of the conventional sensor of Comparative Example 2. Further, the sensor of Comparative Example 3 has low sensitivity, and a sufficient signal could not be obtained. This is considered to be an influence of crystal defects existing in the vicinity of the substrate.

  Next, the influence of the film thickness of the conductive diamond layer was examined. The film thickness of the first insulating diamond layer is 10 μm, the film thickness of the second insulating diamond layer is 20 μm, and the film thickness of the conductive diamond layer is changed between 0.1 to 5.00 μm. Six to fifteen diamond sensors were produced. In addition, the configuration other than the film thickness of each diamond layer in these sensors was the same as that in Example 1 described above. The diamond sensors of Examples 6 to 15 were evaluated in the same manner as in Example 1 described above. The results are shown in Table 2 below.

  As shown in Table 2, in the sensors of Examples 14 and 15 in which the conductive diamond layer has a film thickness of 6 μm or more, the orientation obtained in the first insulating diamond layer is disturbed, and the second insulating property The diamond layer became a polycrystalline diamond layer with no crystal orientation. However, the responsiveness to ultraviolet rays is satisfactory for all the sensors, and the time constant of each sensor is reduced as compared with the sensor of Comparative Example 2 described above. In particular, the sensors of Examples 8 to 11 in which the conductive diamond layer had a thickness of 0.05 to 2.00 μm had good sensitivity and exhibited excellent characteristics as a sensor. On the other hand, the sensors of Examples 6 and 7 in which the film thickness of the conductive diamond layer is less than 0.05 μm are inferior in the collection characteristics because the resistance of the semiconductor layer is high, and the film thickness of the conductive diamond layer is also low. In the sensors of Examples 12 to 15 having a diameter of more than 2.00 μm, the surface morphology of the second insulating diamond layer was broken from the (001) plane, so the sensitivity was lowered.

  In addition, when the response characteristics with respect to the α-ray, soft X-ray, and electron beam were examined for the sensors of Examples 1 to 15 described above, in any case, a signal responding to incidence was obtained, and good time response characteristics were obtained. was gotten. Thereby, it was confirmed that the sensors of Examples 1 to 15 are applicable to light in a wavelength region other than ultraviolet rays.

It is sectional drawing which shows typically the diamond sensor of embodiment of this invention. It is a block diagram which shows the evaluation method of a response characteristic. It is sectional drawing which shows typically the diamond sensor of the conventional planar type structure. It is sectional drawing which shows typically the diamond sensor of the conventional vertical structure. It is sectional drawing which shows the diamond element of patent document 1 typically.

Explanation of symbols

1, 105; conductive substrate 2, 4, 112, 115; highly oriented insulating diamond layer 3; conductive diamond layer 5, 106; surface electrode 6; mount 10, 14, 100, 104, 110; diamond sensor 11; Power source 12; Light source 13; Ultraviolet light 15; Amplifier 16; Digital multimeter 101; Insulating substrate 102; Polycrystalline diamond thin film 103; Comb electrode 111; Substrate 113;

Claims (6)

A substrate, a first insulating diamond layer formed on the substrate, and a conductive diamond layer formed on the first insulating diamond layer and having a thickness smaller than that of the first insulating diamond layer; A second insulating diamond layer formed on the conductive diamond layer, and a surface electrode formed on the second insulating diamond layer, and the second insulating diamond layer includes Carriers generated by incident light are collected by a bias voltage applied between the conductive diamond layer and the surface electrode, and an electrical signal corresponding to the amount of the collected carriers is output. Diamond sensor. 2. The diamond sensor according to claim 1, wherein the first and second insulating diamond layers and the conductive diamond layer are formed of vapor-phase synthesized polycrystalline diamond. The second insulating diamond layer is a highly oriented diamond layer having a (100) surface and crystal grains oriented in one direction with respect to the substrate. 2. The diamond sensor according to 2. The substrate is conductive, and the conductive diamond layer covers the first insulating diamond layer and is in contact with the substrate. The substrate and the conductive diamond layer are electrically The diamond sensor according to claim 1, wherein the diamond sensor is connected to the diamond sensor. The diamond sensor according to any one of claims 1 to 4, wherein the conductive diamond layer is formed of p-type semiconductor diamond to which boron is added. The diamond sensor according to claim 1, wherein the conductive diamond layer has a thickness of 0.05 to 2.00 μm.

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