WO2015198388A1 - Photoelectric conversion film and image capturing device equipped with same - Google Patents

Photoelectric conversion film and image capturing device equipped with same Download PDF

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Publication number
WO2015198388A1
WO2015198388A1 PCT/JP2014/066645 JP2014066645W WO2015198388A1 WO 2015198388 A1 WO2015198388 A1 WO 2015198388A1 JP 2014066645 W JP2014066645 W JP 2014066645W WO 2015198388 A1 WO2015198388 A1 WO 2015198388A1
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layer
generation layer
photoelectric conversion
light
carrier
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PCT/JP2014/066645
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French (fr)
Japanese (ja)
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大島　清朗
亮太 田中
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パイオニア株式会社
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L27/00—Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate
    • H01L27/14—Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate including semiconductor components sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L31/00—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
    • H01L31/08—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof in which radiation controls flow of current through the device, e.g. photoresistors
    • H01L31/10—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof in which radiation controls flow of current through the device, e.g. photoresistors characterised by potential barriers, e.g. phototransistors

Definitions

  • the present invention relates to a photoelectric conversion film that generates an optical carrier (electron / hole pair) according to the amount of incident light and doubles the generated optical carrier, and an imaging apparatus including the photoelectric conversion film.
  • an optical carrier electron / hole pair
  • Each of these photoelectric conversion films includes a plurality of semiconductor layers mainly composed of amorphous selenium (a-Se) and selectively added with arsenic (As), tellurium (Te), lithium fluoride (LiF), and the like. It consists of
  • the photoelectric conversion film (Example 8) of Patent Document 1 has a photocarrier generation layer that absorbs incident light and generates a photocarrier, and a charge multiplication layer that multiplies the generated photocarrier. .
  • amorphous semiconductor layers are laminated in the order of Se + LiF layer and Se + Te layer from the light incident side.
  • the photoelectric conversion film (Example 4) of Patent Document 2 has a P-type photoconductive film sensitized portion, and the P-type photoconductive film sensitized portion has a Se + As + LiF layer, a Se + As + Te + LiF layer, and a Se + As + GaF three layer from the light incident side.
  • a four-layer structure is formed in the order of Se + As layers.
  • the photoelectric conversion film (first embodiment) of Patent Document 3 has a hole injection blocking auxiliary layer, a photocarrier generation layer, and a carrier multiplication layer.
  • the hole injection blocking auxiliary layer is Se + As + LiF
  • the photocarrier generation layer is It is composed of Se + Te.
  • the photoelectric conversion film of Patent Document 4 has a P-type photoconductive film, and has a four-layer structure in the order of Se + As layer, Se + Te + As + LiF layer, Se + Te + As layer, and Se + As layer from the light incident side.
  • lithium fluoride has an electric field relaxation effect that suppresses the electric field on the voltage application side lower than the stack position.
  • optical carriers are mainly generated in front of the Se + LiF layer, and avalanche doubling of the generated optical carriers is mainly performed by a strong electric field behind.
  • photoelectric conversion generation of optical carriers
  • long wavelength light green light and red light
  • avalanche doubling even if the avalanche doubling is appropriately performed, there is a problem that the relative sensitivity of the long wavelength light to the short wavelength light (blue light) is lowered.
  • An object of the present invention is to provide a photoelectric conversion film capable of shifting to avalanche doubling after sufficiently performing long-wavelength photoelectric conversion, particularly of green light or more, and an imaging device including the photoelectric conversion film.
  • Each of the photoelectric conversion films of the present invention is mainly composed of amorphous selenium, a carrier generation layer that generates a photocarrier according to the amount of incident light, a carrier multiplication layer that doubles the generated optical carrier,
  • the carrier generation layer has a first partial generation layer to which lithium fluoride is added at a position deeper than the penetration depth of substantially green light from the front end position of the light incident layer. It is characterized by.
  • the first partial generation layer is preferably disposed in the immediate vicinity of the carrier multiplication layer.
  • the first partial generation layer is disposed at a distance of 0.2 ⁇ m or more and 3.0 ⁇ m or less from the front end position of the layer.
  • the carrier generation layer has a second partial generation layer to which at least one of tellurium, antimony, cadmium, and bismuth is added, and the second partial generation layer is located at a layer front end position than the first partial generation layer. It is preferable to arrange on the side.
  • tellurium is added to the second partial generation layer, and the concentration of the added tellurium is 0.5 wt% or more and 10.0 wt% or less.
  • the carrier generation layer preferably has a third partial generation layer to which arsenic is added, and the third partial generation layer is preferably disposed closer to the layer front end position than the second partial generation layer.
  • the carrier generation layer may have a fourth partial generation layer to which lithium fluoride and arsenic are added instead of the first partial generation layer.
  • Another photoelectric conversion film of the present invention includes a first individual generation layer, a second individual generation layer, and a third individual generation layer from the light incident side, each of which includes a carrier generation layer mainly composed of amorphous selenium.
  • the first individual generation layer includes arsenic added to amorphous selenium
  • the second individual generation layer includes tellurium added to amorphous selenium
  • the third individual generation layer includes amorphous.
  • Lithium fluoride is added to selenium.
  • the imaging device of the present invention faces a light receiving substrate portion having a light-transmitting substrate, a transparent electrode, and the above-described photoelectric conversion film, and faces the light receiving substrate portion in a vacuum space, and emits electrons toward the photoelectric conversion film.
  • An electron-emitting device array, and an electron-emitting substrate portion having a drive circuit for driving the electron-emitting device array are provided.
  • FIG. 1 It is a cross-sectional schematic diagram of the imaging device according to the embodiment. It is a block diagram of the photoelectric conversion film which concerns on 1st Embodiment. It is a component distribution map of the photoelectric conversion film concerning a 1st embodiment.
  • This photoelectric conversion film is a so-called HARP (High-gain Avalanche Rushing amorphous Photoconductor) film, and constitutes an imaging device (imaging device) in combination with a HEED (High-efficiency Electron Emission Device) cold cathode array that constitutes an electron emission source. To do.
  • HARP High-gain Avalanche Rushing amorphous Photoconductor
  • HEED High-efficiency Electron Emission Device
  • FIG. 1 is a schematic cross-sectional view of an imaging apparatus according to an embodiment.
  • an imaging device 100 is arranged so as to face an electron emission substrate portion 101 having an electron emission element array 102 and an electron emission substrate portion 101 with a vacuum space 103 therebetween, and a photoelectric conversion layer 10 (photoelectric conversion). And a mesh electrode 105 disposed in the vacuum space 103 between the electron emission substrate portion 101 and the light receiving substrate portion 104.
  • the electron emission substrate 101 emits electrons as a surface electron emission source, and the mesh electrode 105 controls the trajectory of electrons (electron beams) emitted from the electron emission substrate 101 and accelerates the electrons.
  • the light receiving substrate unit 104 receives light to be imaged and becomes a target for electrons emitted from the electron emission substrate unit 101.
  • the electron-emitting substrate unit 101 includes a back substrate 111 made of silicon or the like, a drive circuit layer 112 formed on the back substrate 111, and an electron-emitting device array 102 formed on the drive circuit layer 112. is doing.
  • An active matrix drive circuit 113 (switching circuit) is formed in the drive circuit layer 112.
  • a horizontal scanning circuit (driver) and a vertical scanning circuit (driver) that control driving of the active matrix driving circuit 113 are disposed in the peripheral portion of the back substrate 111. Then, the plurality of electron-emitting devices 102 a of the electron-emitting device array 102 are driven dot-sequentially by the horizontal scanning circuit and the vertical scanning circuit via the active matrix driving circuit 113.
  • electrons electron beams
  • the emitted electrons are combined with the hole pattern of the photoelectric conversion layer 10 (details will be described later).
  • the mesh electrode 105 is formed of a metal plate or the like having a plurality of openings, and controls the trajectory of electrons emitted from the electron-emitting device array 102 and accelerates electrons toward the photoelectric conversion layer 10.
  • the mesh electrode 105 absorbs surplus electrons. For this reason, a voltage that is significantly higher than the drive voltage of the drive circuit layer 112 is applied to the mesh electrode 105.
  • Electrons emitted from the electron emission substrate 101 are drawn out to the photoelectric conversion layer 10 side by the voltage applied to the mesh electrode 105, and also due to an electric field generated between the electron emission element array 102 and the photoelectric conversion layer 10. And converged on the back surface of the photoelectric conversion layer 10. The emitted electrons are combined with the hole pattern of the photoelectric conversion layer 10.
  • the light receiving substrate unit 104 includes a light transmitting side light transmitting substrate 121, a transparent electrode layer 122 formed on the back surface (lower surface) of the light transmitting substrate 121, and the photoelectric conversion layer 10 formed on the back surface of the transparent electrode layer 122. And a landing auxiliary layer 123 formed on the back surface of the photoelectric conversion layer 10.
  • the light receiving substrate unit 104 also includes a circuit for supplying signals and voltages necessary for driving, a circuit for outputting the detected video signal, and the like.
  • the translucent substrate 121 is made of glass or the like that is transparent to visible light when the object to be imaged is visible light, sapphire or quartz glass or the like when it is ultraviolet light, and beryllium or the like when it is X-ray. Is formed.
  • the transparent electrode layer 122 is made of indium oxide (In 2 O 3 ) or the like.
  • the photoelectric conversion layer 10 is formed of a semiconductor layer mainly composed of amorphous selenium (a-Se) (details will be described later). Further, the landing auxiliary layer 123 is made of antimony sulfide (Sb 2 S 3 ) or the like.
  • the generated holes are accelerated by a strong electric field applied to the transparent electrode layer 122 and continuously collide with atoms constituting the photoelectric conversion layer 10 to generate new electron / hole pairs (avalanche multiplication). .
  • the avalanche-multiplied holes are accumulated near the back surface of the photoelectric conversion layer 10 to form a hole pattern corresponding to the incident light image. And the electric current at the time of combining this hole pattern and the electron discharge
  • FIG. 2 shows the light receiving substrate 104 in a horizontal direction, and here, the description will proceed with the front side as “front” and the back side as “rear” with respect to the incident direction of light (indicated by arrows).
  • the light receiving substrate unit 104 includes the light transmitting substrate 121, the transparent electrode layer 122, the photoelectric conversion layer 10, and the landing auxiliary layer 123 in this order from the front side (incident side).
  • the photoelectric conversion layer 10 includes a carrier generation layer 11 that generates optical carriers (electron / hole pairs) according to the amount of incident light, and a carrier multiplication layer 12 that doubles the generated optical carriers by avalanche. I have. Needless to say, the carrier generation layer 11 is disposed on the transparent electrode layer 122 side, and the carrier multiplication layer 12 is disposed on the landing auxiliary layer 123 side.
  • Both the carrier generation layer 11 and the carrier multiplication layer 12 are formed of a semiconductor layer mainly composed of amorphous selenium (a-Se).
  • the carrier generation layer 11 includes, in order from the front side, a front generation layer 21 in which arsenic (As) is added to selenium (Se) (a-Se + As layer: third partial generation layer: first individual generation layer), selenium.
  • Intermediate part generation layer 22 (a-Se + Te layer: second partial generation layer: second individual generation layer) with tellurium (Te) added to (Se), and lithium fluoride (LiF) added to selenium (Se)
  • a rear generation layer 23 (a-Se + LiF layer: first partial generation layer: third individual generation layer).
  • FIG. 3 shows the component distribution of the carrier generation layer 11 and the carrier multiplication layer 12 configured as described above.
  • the carrier generation layer 11 and the carrier multiplication layer 12 constituting the photoelectric conversion layer 10 are continuously formed by a vacuum deposition method.
  • vapor deposition nozzles for selenium (Se), arsenic (As), tellurium (Te), and lithium fluoride (LiF) are prepared, respectively.
  • the deposition nozzles for arsenic (As), tellurium (Te), and lithium fluoride (LiF) are selectively driven. Be filmed.
  • the photoelectric conversion layer 10 of the first embodiment includes an a-Se + As layer (front generation layer 21) having a thickness of 1000 mm from the front layer end position F to the rear layer end position, and a film An a-Se layer having a thickness of 500 mm, an a-Se + Te layer having a thickness of 2000 mm (intermediate generation layer 22), an a-Se layer having a thickness of 500 mm, and an a-Se + LiF layer having a thickness of 800 mm (rear generation layer 23) A carrier generation layer 11 is formed.
  • a carrier multiplication layer 12 made of an a-Se layer is formed after the carrier generation layer 11. And the film thickness of the whole photoelectric converting layer 10 is about 4 micrometers.
  • the a-Se + LiF layer (rear generation layer 23) is disposed in front of the carrier multiplication layer 12.
  • the a-Se + Te layer (intermediate generation layer 22) is arranged on the front side of the front end position F, which is in front of the rear generation layer 23, and the a-Se + As layer (front generation layer 21) is the intermediate generation layer 22. It is arrange
  • the a-Se + LiF layer (rear generation layer 23) is disposed at a distance of 0.2 ⁇ m or more and 3.0 ⁇ m or less from the front end position F of the layer, and has a film thickness of 500 mm or more and 1000 mm or less. Is preferred.
  • the rear generation layer 23 of the first embodiment is disposed at a distance of 0.4 ⁇ m from the layer front end position F, and has a layer thickness of 800 mm.
  • the a-Se + Te layer (intermediate portion generation layer 22) is preferably arranged at a distance of 0 mm or more from the front end position F of the layer and has a thickness of 500 mm or more and 2.0 ⁇ m or less.
  • the intermediate portion generation layer 22 of the first embodiment is disposed at a distance of 0.15 ⁇ m from the layer front end position F, and has a layer thickness of 2000 mm.
  • Tellurium (Te) also becomes a nucleus of selenium crystallization as an impurity of (Se) of selenium, and “white scratches” (white spot-like defects: electric field concentration occurs in a portion where the resistance is reduced by partial crystallization of selenium. Which occurs and causes a white glow). For this reason, it is preferable to keep the tellurium concentration low in the intermediate portion generation layer 22. That is, in the intermediate portion generation layer 22, the tellurium concentration is preferably 0.5 wt% or more and 10.0 wt% or less. In the intermediate generation layer 22 of the first embodiment, the tellurium concentration is about 2.5 wt%.
  • lithium fluoride (LiF) added (doped) to the a-Se + LiF layer (rear generation layer 23) forms a hole trap level and blocks holes from the transparent electrode layer 122.
  • this prevention effect is that LiF is arranged in the vicinity of the front end position F of the photoelectric conversion layer 10 (carrier generation layer 11) as in the prior art. Even if it is not done, it is considered to be achieved by making the interface state between the transparent electrode layer 122 and the photoelectric conversion layer 10 appropriate.
  • LiF has an electric field relaxation effect in front of the light penetration direction.
  • avalanche doubling is suppressed and light carrier generation is mainly performed in each of the layers ahead of the a-Se + LiF layer (rear generation layer 23).
  • an avalanche doubling of the generated optical carrier is mainly caused by a strong electric field. That is, the carrier generation layer 11 is configured forward from the rear end of the a-Se + LiF layer (rear generation layer 23), and the carrier multiplication layer 12 is configured rearward.
  • the front end position of the a-Se + LiF layer (rear generation layer 23) is a depth position of 0.4 ⁇ m from the layer front end position F. That is, an a-Se + LiF layer (rear generation layer 23) is formed at a depth position separated by 0.4 ⁇ m from the front end position F of the layer.
  • the light penetration depth which is the depth at which the light intensity is attenuated to 1 / e 2 , is about 0.1 ⁇ m for blue light (B: 440 nm), about 0.23 ⁇ m for green light (G: 540 nm), It is about 2.8 ⁇ m with red light (R: 620 nm).
  • an a-Se + LiF layer (rear generation layer 23) is disposed at a position deeper than the penetration depth of green light from the blue light. Therefore, in the photoelectric conversion layer 10 (carrier generation layer 11), at least blue light and green light photoelectric conversion (generation of optical carriers) is sufficiently performed due to the electric field relaxation effect. Further, the optical carriers generated in this way are avalanche multiplied by the subsequent carrier multiplication layer 12.
  • the photoelectric conversion layer 10 of the present embodiment has obtained a test result that the relative sensitivity of red light does not decrease in a high-temperature storage environment as follows.
  • FIG. 4 shows the test results of the primary conversion efficiency in high-temperature storage for the photoelectric conversion layer 10 (a) of the first embodiment and the photoelectric conversion film (b) of Patent Document 1 described above.
  • 50% white light is applied under a voltage condition that does not cause avalanche, and the luminance when a predetermined current flows is measured to evaluate the sensitivity.
  • the relative value is calculated by reference luminance / sample luminance.
  • the horizontal axis represents “heating time (h) at 50 ° C.”, and the vertical axis represents “sensitivity equivalent luminance value”, which represents the sensitivity in a high-temperature storage (acceleration) environment.
  • the a-Se + LiF layer (rear generation layer 23) in the carrier generation layer 11 is made to have a penetration depth of substantially green light (which is 0.2 ⁇ m). Since it is arranged at a deep position, the electric field relaxation region by LiF can be widened (long). Thereby, after sufficient photoelectric conversion of the imaging target light can be performed, avalanche multiplication can be performed, and an improvement in relative quantum efficiency (sensitivity improvement) of each color light of R, G, and B can be achieved. In particular, the quantum efficiency of green light can be improved as compared with the conventional one. In addition, the quantum efficiency of red light in a high-temperature storage environment can be improved, and the occurrence of “white scratches” can be suppressed.
  • tellurium (Te) is added to the intermediate portion generation layer 22, but antimony (Sb), cadmium (Cd), and bismuth (Bi), which have a lower band gap than selenium (Se). One or more of them may be added.
  • the photoelectric conversion layer 10A of 2nd Embodiment is demonstrated in detail.
  • the a-Se + As layer front generation layer 21
  • the carrier generation layer 11 is formed of an a-Se layer having a thickness of 3000 ⁇ and an a-Se + LiF layer (rear generation layer 23) having a thickness of 800 ⁇ .
  • the film thickness of the photoelectric conversion layer 10A including the carrier multiplication layer 12 is about 4 ⁇ m.
  • the a-Se + LiF layer (rear generation layer 23) is disposed in front of the carrier multiplication layer 12, and the front end position thereof is a depth of 0.4 ⁇ m from the layer front end position F. Further, the a-Se + Te layer (intermediate generation layer 22) is omitted, and the front end position F of the layer is coincident with the front end position of the a-Se + As layer (front generation layer 21).
  • the a-Se + LiF layer (rear generation layer 23) in the carrier generation layer 11 is deeper than the penetration depth of about green light (which is 0.2 ⁇ m). Since it is arranged at a position, the electric field relaxation region by LiF can be widened (long). Thereby, the quantum efficiency of green light can be improved. In this case, in the actual measurement value, the quantum efficiency of 550 nm wavelength light (green light) was improved by 1.7 times. In addition, the quantum efficiency of red light in a high-temperature storage environment can be improved, and the occurrence of “white scratches” can be suppressed.
  • the rear generation layer 23 may be an a-Se + Te + LiF layer containing tellurium (modified example).
  • the quantum efficiency of light having a wavelength of 550 nm (green light) is improved by 1.9 times.
  • the photoelectric converting layer 10B of 3rd Embodiment is demonstrated in detail.
  • an a-Se + As layer front generation layer 21 having a thickness of 1000 mm from the front end position F to the rear end position of the layer.
  • a carrier generation layer 11 comprising a layer 23B).
  • the film thickness of the photoelectric conversion layer 10B including the carrier multiplication layer 12 is about 4 ⁇ m.
  • the a-Se + As + LiF layer (rear generation layer 23B) is disposed in front of the carrier multiplication layer 12, and the front end position thereof is a depth of 0.4 ⁇ m from the front end position F of the layer. Further, the a-Se + Te layer (intermediate generation layer 22) is disposed on the layer front end position F side with respect to the rear generation layer 23B, and the a-Se + As layer (front generation layer 21) is more than the intermediate generation layer 22. It is arrange
  • the a-Se + As + LiF layer (rear generation layer 23B) in the carrier generation layer 11 is deeper than the penetration depth of about green light (which is 0.2 ⁇ m). Since it is arranged at a position, the electric field relaxation region by LiF can be widened (long). Thereby, the quantum efficiency of green light can be improved. In this case, in the actual measurement value, the quantum efficiency of 550 nm wavelength light (green light) was improved by 1.7 times. In addition, the quantum efficiency of red light in a high-temperature storage environment can be improved, and the occurrence of “white scratches” can be suppressed.

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Abstract

Provided are a photoelectric conversion film and the like such that avalanche multiplication can be caused after photoelectric conversion of especially green light is sufficiently performed. The photoelectric conversion film (10) of the present invention is equipped with a carrier generation layer (11) for generating an optical carrier in accordance with the amount of incident light and a carrier multiplication layer (12) for avalanche-multiplying the generated optical carrier, each of the layers consisting mainly of amorphous selenium, wherein the carrier generation layer (11) has a rear generation layer (23) to which lithium fluoride is added, said rear generation layer (23) lying at a position deeper than a penetration depth of 0.2 μm for substantially green light from a layer front end position (F) at which light is incident.

Description

光電変換膜およびこれを備えた撮像装置Photoelectric conversion film and imaging apparatus provided with the same
　本発明は、入射した光の光量に応じて光キャリア（電子・正孔対）を生成すると共に、生成した光キャリアをアバランシェ倍増させる光電変換膜およびこれを備えた撮像装置に関する。 The present invention relates to a photoelectric conversion film that generates an optical carrier (electron / hole pair) according to the amount of incident light and doubles the generated optical carrier, and an imaging apparatus including the photoelectric conversion film.
　従来の光電変換膜として、後述する特許文献１、特許文献２、特許文献３および特許文献４にそれぞれ記載のものが知られている。これらの光電変換膜は、いずれもアモルファスセレン（ａ－Ｓｅ）を主成分とし、これにヒ素（Ａｓ）、テルル（Ｔｅ）、フッ化リチウム（ＬｉＦ）等を選択的に添加した複数の半導体層で構成されている。 As conventional photoelectric conversion films, those described in Patent Document 1, Patent Document 2, Patent Document 3 and Patent Document 4, which will be described later, are known. Each of these photoelectric conversion films includes a plurality of semiconductor layers mainly composed of amorphous selenium (a-Se) and selectively added with arsenic (As), tellurium (Te), lithium fluoride (LiF), and the like. It consists of
　特許文献１の光電変換膜（実施例８）は、入射光を吸収して光キャリアを発生させる光キャリア発生層と、発生した光キャリアを増倍させる電荷増倍層と、を有している。光キャリア発生層は、光の入射側からＳｅ＋ＬｉＦ層、Ｓｅ＋Ｔｅ層の順で非晶質半導体層が積層されている。
　特許文献２の光電変換膜（実施例４）は、Ｐ型光導電膜増感部分を有し、Ｐ型光導電膜増感部分は、光の入射側からＳｅ＋Ａｓ＋ＬｉＦ層、Ｓｅ＋Ａｓ＋Ｔｅ＋ＬｉＦ層、Ｓｅ＋Ａｓ＋ＧａＦ３層、Ｓｅ＋Ａｓ層の順で４層構造を為している。
　特許文献３の光電変換膜（第１実施形態）は、正孔注入阻止補助層、光キャリア発生層およびキャリア増倍層を有し、正孔注入阻止補助層はＳｅ＋Ａｓ＋ＬｉＦで、光キャリア発生層はＳｅ＋Ｔｅで構成されている。
　特許文献４の光電変換膜は、Ｐ型光導電膜を有し、光の入射側からＳｅ＋Ａｓ層、Ｓｅ＋Ｔｅ＋Ａｓ＋ＬｉＦ層、Ｓｅ＋Ｔｅ＋Ａｓ層、Ｓｅ＋Ａｓ層の順で４層構造を為している。 The photoelectric conversion film (Example 8) of Patent Document 1 has a photocarrier generation layer that absorbs incident light and generates a photocarrier, and a charge multiplication layer that multiplies the generated photocarrier. . In the photocarrier generation layer, amorphous semiconductor layers are laminated in the order of Se + LiF layer and Se + Te layer from the light incident side.
The photoelectric conversion film (Example 4) of Patent Document 2 has a P-type photoconductive film sensitized portion, and the P-type photoconductive film sensitized portion has a Se + As + LiF layer, a Se + As + Te + LiF layer, and a Se + As + GaF three layer from the light incident side. A four-layer structure is formed in the order of Se + As layers.
The photoelectric conversion film (first embodiment) of Patent Document 3 has a hole injection blocking auxiliary layer, a photocarrier generation layer, and a carrier multiplication layer. The hole injection blocking auxiliary layer is Se + As + LiF, and the photocarrier generation layer is It is composed of Se + Te.
The photoelectric conversion film of Patent Document 4 has a P-type photoconductive film, and has a four-layer structure in the order of Se + As layer, Se + Te + As + LiF layer, Se + Te + As layer, and Se + As layer from the light incident side.
　このような光電変換膜では、光キャリアを発生させる発生層の光入射側に、正孔に対する捕獲準位を形成するフッ化リチウム（ＬｉＦ）を添加したセレン（Ｓｅ）層を配置することで、印加電圧による透明電極からの正孔をブロックし、暗電流や残像の増加等を防止している。また、長波長（特に赤色）の光の感度向上（量子効率の向上）を図るべく、テルル（Ｔｅ）を添加したセレン（Ｓｅ）層を、フッ化リチウム（ＬｉＦ）を添加したセレン（Ｓｅ）層の後方に配置している。 In such a photoelectric conversion film, by arranging a selenium (Se) layer to which lithium fluoride (LiF) that forms a trap level for holes is added on the light incident side of a generation layer that generates photocarriers, Holes from the transparent electrode due to the applied voltage are blocked to prevent an increase in dark current and afterimage. Further, in order to improve the sensitivity (increase in quantum efficiency) of light having a long wavelength (especially red), the selenium (Se) layer added with tellurium (Te) is replaced with selenium (Se) added with lithium fluoride (LiF). Located behind the layer.
特開平６－９６６８８号公報JP-A-6-96688 特開昭６０－２４５２８３号公報JP 60-245283 A 特開２００２－５７３１４号公報JP 2002-57314 A 特開昭５７－８０６３７号公報JP-A-57-80637
　ところで、フッ化リチウム（ＬｉＦ）は、その積層位置より電圧印加側の電界を低く抑制する電界緩和効果を有している。言い換えれば、電圧印加側から光を入射した場合、Ｓｅ＋ＬｉＦ層を境に、その前方では光キャリアの発生が主体となり、後方では強い電界により、発生した光キャリアのアバランシェ倍増が主体となる。このため、Ｓｅ＋ＬｉＦ層の後方に、赤色光を吸収すべくＳｅ＋Ｔｅ層を配置しても、長波長の光（緑色光および赤色光）の光電変換（光キャリアの発生）が不十分な状態で、アバランシェ倍増に移行してしまう。したがって、アバランシェ倍増が適切に行われても、短波長の光（青色光）に対する長波長の光の相対的な感度が低下してしまう問題があった。 By the way, lithium fluoride (LiF) has an electric field relaxation effect that suppresses the electric field on the voltage application side lower than the stack position. In other words, when light is incident from the voltage application side, optical carriers are mainly generated in front of the Se + LiF layer, and avalanche doubling of the generated optical carriers is mainly performed by a strong electric field behind. For this reason, even if the Se + Te layer is disposed behind the Se + LiF layer to absorb red light, photoelectric conversion (generation of optical carriers) of long wavelength light (green light and red light) is insufficient. It shifts to avalanche doubling. Therefore, even if the avalanche doubling is appropriately performed, there is a problem that the relative sensitivity of the long wavelength light to the short wavelength light (blue light) is lowered.
　本発明は、特に緑色光以上の長波長の光電変換を十分に行ってから、アバランシェ倍増に移行させることができる光電変換膜およびこれを備えた撮像装置を提供することを課題としている。 An object of the present invention is to provide a photoelectric conversion film capable of shifting to avalanche doubling after sufficiently performing long-wavelength photoelectric conversion, particularly of green light or more, and an imaging device including the photoelectric conversion film.
　本発明の光電変換膜は、それぞれがアモルファスセレンを主成分とする、入射した光の光量に応じて光キャリアを生成するキャリア発生層と、生成した光キャリアをアバランシェ倍増させるキャリア増倍層と、を備えた光電変換膜であって、キャリア発生層は、光が入射する層前端位置から略緑色光の侵入深さよりも深い位置に、フッ化リチウムが添加された第１部分発生層を有していることを特徴とする。 Each of the photoelectric conversion films of the present invention is mainly composed of amorphous selenium, a carrier generation layer that generates a photocarrier according to the amount of incident light, a carrier multiplication layer that doubles the generated optical carrier, The carrier generation layer has a first partial generation layer to which lithium fluoride is added at a position deeper than the penetration depth of substantially green light from the front end position of the light incident layer. It is characterized by.
　この場合、第１部分発生層は、キャリア増倍層の直近に配置されていることが好ましい。 In this case, the first partial generation layer is preferably disposed in the immediate vicinity of the carrier multiplication layer.
　また、第１部分発生層は、層前端位置から０．２μｍ以上３．０μｍ以下の距離、隔てて配置されていることが好ましい。 Further, it is preferable that the first partial generation layer is disposed at a distance of 0.2 μm or more and 3.0 μm or less from the front end position of the layer.
　さらに、キャリア発生層は、テルル、アンチモン、カドミウムおよびビスマスのうちの、少なくとも１つが添加された第２部分発生層を有し、第２部分発生層は、第１部分発生層よりも層前端位置側に配置されていることが好ましい。 Further, the carrier generation layer has a second partial generation layer to which at least one of tellurium, antimony, cadmium, and bismuth is added, and the second partial generation layer is located at a layer front end position than the first partial generation layer. It is preferable to arrange on the side.
　この場合、第２部分発生層には、テルルが添加され、添加されたテルルの濃度が、０．５ｗｔ％以上１０．０ｗｔ％以下であることが好ましい。 In this case, it is preferable that tellurium is added to the second partial generation layer, and the concentration of the added tellurium is 0.5 wt% or more and 10.0 wt% or less.
　また、キャリア発生層は、ヒ素が添加された第３部分発生層を有し、第３部分発生層は、第２部分発生層よりも層前端位置側に配置されていることが好ましい。 Further, the carrier generation layer preferably has a third partial generation layer to which arsenic is added, and the third partial generation layer is preferably disposed closer to the layer front end position than the second partial generation layer.
　一方、キャリア発生層は、第１部分発生層に代えて、フッ化リチウムおよびヒ素が添加された第４部分発生層を、有していてもよい。 On the other hand, the carrier generation layer may have a fourth partial generation layer to which lithium fluoride and arsenic are added instead of the first partial generation layer.
　本発明の他の光電変換膜は、光が入射する側から第１個別発生層、第２個別発生層および第３個別発生層を有し、それぞれがアモルファスセレンを主成分とするキャリア発生層を備えた光電変換膜であって、第１個別発生層には、アモルファスセレンにヒ素が添加され、第２個別発生層には、アモルファスセレンにテルルが添加され、第３個別発生層には、アモルファスセレンにフッ化リチウムが添加されていることを特徴とする。 Another photoelectric conversion film of the present invention includes a first individual generation layer, a second individual generation layer, and a third individual generation layer from the light incident side, each of which includes a carrier generation layer mainly composed of amorphous selenium. The first individual generation layer includes arsenic added to amorphous selenium, the second individual generation layer includes tellurium added to amorphous selenium, and the third individual generation layer includes amorphous. Lithium fluoride is added to selenium.
　本発明の撮像装置は、透光性基板、透明電極および上記した光電変換膜を有する受光基板部と、真空空間を存して受光基板部に対面し、光電変換膜に向かって電子を放出する電子放出素子アレイ、および電子放出素子アレイを駆動する駆動回路を有する電子放出基板部と、を備えたことを特徴とする。 The imaging device of the present invention faces a light receiving substrate portion having a light-transmitting substrate, a transparent electrode, and the above-described photoelectric conversion film, and faces the light receiving substrate portion in a vacuum space, and emits electrons toward the photoelectric conversion film. An electron-emitting device array, and an electron-emitting substrate portion having a drive circuit for driving the electron-emitting device array are provided.
実施形態に係る撮像装置の断面模式図である。It is a cross-sectional schematic diagram of the imaging device according to the embodiment. 第１実施形態に係る光電変換膜の構成図である。It is a block diagram of the photoelectric conversion film which concerns on 1st Embodiment. 第１実施形態に係る光電変換膜の成分分布図である。It is a component distribution map of the photoelectric conversion film concerning a 1st embodiment. 第１実施形態の光電変換膜につき、高温保管における一次変換効率の試験結果を表した図（ａ）、および特許文献１の光電変換膜につき、高温保管における一次変換効率の試験結果を表した図（ｂ）である。The figure (a) showing the test result of the primary conversion efficiency in high temperature storage about the photoelectric conversion film of 1st Embodiment, and the figure showing the test result of the primary conversion efficiency in high temperature storage about the photoelectric conversion film of patent document 1 (B). 第２実施形態に係る光電変換膜の成分分布図である。It is a component distribution map of the photoelectric conversion film concerning a 2nd embodiment. 第３実施形態に係る光電変換膜の成分分布図である。It is a component distribution map of the photoelectric conversion film concerning a 3rd embodiment.
　以下、添付の図面を参照して、本発明の実施形態に係る光電変換膜およびこれを備えた撮像装置について説明する。この光電変換膜は、いわゆるＨＡＲＰ(High-gain Avalanche Rushing amorphous Photoconductor)膜であり、電子放出源を構成するＨＥＥＤ（High-efficiency Electron Emission Device）冷陰極アレイと組み合わせて撮像装置（撮像デバイス）を構成するものである。以下、撮像装置、光電変換膜の順で説明を進める。 Hereinafter, a photoelectric conversion film according to an embodiment of the present invention and an image pickup apparatus including the same will be described with reference to the accompanying drawings. This photoelectric conversion film is a so-called HARP (High-gain Avalanche Rushing amorphous Photoconductor) film, and constitutes an imaging device (imaging device) in combination with a HEED (High-efficiency Electron Emission Device) cold cathode array that constitutes an electron emission source. To do. Hereinafter, the description proceeds in the order of the imaging device and the photoelectric conversion film.
　図１は、実施形態に係る撮像装置の断面模式図である。同図に示すように、撮像装置１００は、電子放出素子アレイ１０２を有する電子放出基板部１０１と、真空空間１０３を存して電子放出基板部１０１に対向配置され、光電変換層１０（光電変換膜）を有する受光基板部１０４と、電子放出基板部１０１と受光基板部１０４との間の真空空間１０３に配設されたメッシュ電極１０５と、を備えている。 FIG. 1 is a schematic cross-sectional view of an imaging apparatus according to an embodiment. As shown in the figure, an imaging device 100 is arranged so as to face an electron emission substrate portion 101 having an electron emission element array 102 and an electron emission substrate portion 101 with a vacuum space 103 therebetween, and a photoelectric conversion layer 10 (photoelectric conversion). And a mesh electrode 105 disposed in the vacuum space 103 between the electron emission substrate portion 101 and the light receiving substrate portion 104.
　電子放出基板部１０１は、面電子放出源として電子を放出し、メッシュ電極１０５は、電子放出基板部１０１から放出された電子（電子ビーム）の軌道を制御し且つ電子を加速する。受光基板部１０４は、撮像対象となる光を受光すると共に、電子放出基板部１０１から放出された電子のターゲットとなる。 The electron emission substrate 101 emits electrons as a surface electron emission source, and the mesh electrode 105 controls the trajectory of electrons (electron beams) emitted from the electron emission substrate 101 and accelerates the electrons. The light receiving substrate unit 104 receives light to be imaged and becomes a target for electrons emitted from the electron emission substrate unit 101.
　電子放出基板部１０１は、シリコン等で構成された背面基板１１１と、背面基板１１１上に形成された駆動回路層１１２と、駆動回路層１１２上に形成された電子放出素子アレイ１０２と、を有している。駆動回路層１１２には、アクティブマトリクス駆動回路１１３（スイッチング回路）が形成されている。また、背面基板１１１の周辺部には、図示しないが、アクティブマトリクス駆動回路１１３の駆動を制御する水平走査回路（ドライバ）および垂直走査回路（ドライバ）が配設されている。そして、この水平走査回路および垂直走査回路により、アクティブマトリクス駆動回路１１３を介して、電子放出素子アレイ１０２の複数の電子放出素子１０２ａが点順次駆動される。 The electron-emitting substrate unit 101 includes a back substrate 111 made of silicon or the like, a drive circuit layer 112 formed on the back substrate 111, and an electron-emitting device array 102 formed on the drive circuit layer 112. is doing. An active matrix drive circuit 113 (switching circuit) is formed in the drive circuit layer 112. Although not shown, a horizontal scanning circuit (driver) and a vertical scanning circuit (driver) that control driving of the active matrix driving circuit 113 are disposed in the peripheral portion of the back substrate 111. Then, the plurality of electron-emitting devices 102 a of the electron-emitting device array 102 are driven dot-sequentially by the horizontal scanning circuit and the vertical scanning circuit via the active matrix driving circuit 113.
　すなわち、各電子放出素子１０２ａの駆動により、電子放出素子１０２ａの複数のエミッションサイト１１５から、光電変換層１０をターゲットとして電子（電子ビーム）が放出される。そして、この放出された電子は、光電変換層１０の正孔パターンと結合する（詳細は後述する）。 That is, by driving each electron-emitting device 102a, electrons (electron beams) are emitted from the plurality of emission sites 115 of the electron-emitting device 102a using the photoelectric conversion layer 10 as a target. The emitted electrons are combined with the hole pattern of the photoelectric conversion layer 10 (details will be described later).
　メッシュ電極１０５は、複数の開口を有しする金属板等で形成され、電子放出素子アレイ１０２から放出された電子の軌道を制御すると共に電子を光電変換層１０に向かって加速する。また、メッシュ電極１０５は、余剰電子を吸収する。このため、メッシュ電極１０５には、駆動回路層１１２の駆動電圧に比べて格段に高い電圧が印加される。 The mesh electrode 105 is formed of a metal plate or the like having a plurality of openings, and controls the trajectory of electrons emitted from the electron-emitting device array 102 and accelerates electrons toward the photoelectric conversion layer 10. The mesh electrode 105 absorbs surplus electrons. For this reason, a voltage that is significantly higher than the drive voltage of the drive circuit layer 112 is applied to the mesh electrode 105.
　電子放出基板部１０１から放出された電子は、メッシュ電極１０５に印加された電圧により、光電変換層１０側に引き出されると共に、電子放出素子アレイ１０２と光電変換層１０との間に生じた電界により、光電変換層１０の裏面に収束される。そして、この放出された電子は、光電変換層１０の正孔パターンと結合する。 Electrons emitted from the electron emission substrate 101 are drawn out to the photoelectric conversion layer 10 side by the voltage applied to the mesh electrode 105, and also due to an electric field generated between the electron emission element array 102 and the photoelectric conversion layer 10. And converged on the back surface of the photoelectric conversion layer 10. The emitted electrons are combined with the hole pattern of the photoelectric conversion layer 10.
　受光基板部１０４は、受光側の透光性基板１２１と、透光性基板１２１の裏面（下面）に形成された透明電極層１２２と、透明電極層１２２の裏面に形成された光電変換層１０と、光電変換層１０の裏面に形成されたランディング補助層１２３と、を有している。また、図示では省略したが、受光基板部１０４は、駆動に必要な信号や電圧を供給する回路、検出した映像信号を出力する回路等も有している。 The light receiving substrate unit 104 includes a light transmitting side light transmitting substrate 121, a transparent electrode layer 122 formed on the back surface (lower surface) of the light transmitting substrate 121, and the photoelectric conversion layer 10 formed on the back surface of the transparent electrode layer 122. And a landing auxiliary layer 123 formed on the back surface of the photoelectric conversion layer 10. Although not shown in the drawing, the light receiving substrate unit 104 also includes a circuit for supplying signals and voltages necessary for driving, a circuit for outputting the detected video signal, and the like.
　透光性基板１２１は、撮像対象が可視光である場合には可視光に対し透明なガラス等で、紫外線である場合にはサファイアや石英ガラス等で、Ｘ線である場合にはベリリウム等で形成されている。透明電極層１２２は、酸化インジウム（Ｉｎ２Ｏ３）等で形成されている。また、光電変換層１０は、アモルファス・セレン（ａ－Ｓｅ）を主成分とする半導体層で形成されている（詳細は、後述する）。さらに、ランディング補助層１２３は、硫化アンチモン（Ｓｂ２Ｓ３）等で形成されている。 The translucent substrate 121 is made of glass or the like that is transparent to visible light when the object to be imaged is visible light, sapphire or quartz glass or the like when it is ultraviolet light, and beryllium or the like when it is X-ray. Is formed. The transparent electrode layer 122 is made of indium oxide (In 2 O 3 ) or the like. The photoelectric conversion layer 10 is formed of a semiconductor layer mainly composed of amorphous selenium (a-Se) (details will be described later). Further, the landing auxiliary layer 123 is made of antimony sulfide (Sb 2 S 3 ) or the like.
　透光性基板１２１の表面から入射した光は、光電変換層１０においてその光量に応じた電子・正孔対（光キャリア）を生成させる。生成した正孔は透明電極層１２２に印加された強い電界により加速され、光電変換層１０を構成する原子と連続的に衝突して、新たな電子・正孔対を生成する（アバランシェ増倍）。アバランシェ増倍された正孔は、光電変換層１０の裏面付近に蓄積され、入射光像に対応する正孔パターンを形成する。そして、この正孔パターンと電子放出素子１０２ａ（電子放出素子アレイ１０２）から放出された電子とが結合する際の電流が、入射光像に応じた映像信号として検出される。 Light incident from the surface of the translucent substrate 121 generates electron / hole pairs (photocarriers) corresponding to the amount of light in the photoelectric conversion layer 10. The generated holes are accelerated by a strong electric field applied to the transparent electrode layer 122 and continuously collide with atoms constituting the photoelectric conversion layer 10 to generate new electron / hole pairs (avalanche multiplication). . The avalanche-multiplied holes are accumulated near the back surface of the photoelectric conversion layer 10 to form a hole pattern corresponding to the incident light image. And the electric current at the time of combining this hole pattern and the electron discharge | released from the electron emission element 102a (electron emission element array 102) is detected as a video signal according to an incident light image.
［第１実施形態］
　次に、図２を参照して、第１実施形態の光電変換層１０について詳細に説明する。なお、図２は、受光基板部１０４を横向きに表しており、ここでは、光の入射方向（矢印で示した）に対し、手前側を「前」奥側を「後」として説明を進める。
　上述のように、受光基板部１０４は前側（入射側）から順に、透光性基板１２１、透明電極層１２２、光電変換層１０およびランディング補助層１２３を有している。また、光電変換層１０は、入射した光の光量に応じて光キャリア（電子・正孔対）を生成するキャリア発生層１１と、生成した光キャリアをアバランシェ倍増させるキャリア増倍層１２と、を備えている。言うまでもないが、キャリア発生層１１は透明電極層１２２側に、キャリア増倍層１２はランディング補助層１２３側に配設されている。 [First Embodiment]
Next, with reference to FIG. 2, the photoelectric conversion layer 10 of 1st Embodiment is demonstrated in detail. Note that FIG. 2 shows the light receiving substrate 104 in a horizontal direction, and here, the description will proceed with the front side as “front” and the back side as “rear” with respect to the incident direction of light (indicated by arrows).
As described above, the light receiving substrate unit 104 includes the light transmitting substrate 121, the transparent electrode layer 122, the photoelectric conversion layer 10, and the landing auxiliary layer 123 in this order from the front side (incident side). The photoelectric conversion layer 10 includes a carrier generation layer 11 that generates optical carriers (electron / hole pairs) according to the amount of incident light, and a carrier multiplication layer 12 that doubles the generated optical carriers by avalanche. I have. Needless to say, the carrier generation layer 11 is disposed on the transparent electrode layer 122 side, and the carrier multiplication layer 12 is disposed on the landing auxiliary layer 123 side.
　キャリア発生層１１およびキャリア増倍層１２は、いずれもアモルファス・セレン（ａ－Ｓｅ）を主成分とする半導体層で形成されている。そして、キャリア発生層１１は前側から順に、セレン（Ｓｅ）にヒ素（Ａｓ）が添加された前部発生層２１（ａ－Ｓｅ＋Ａｓ層：第３部分発生層：第１個別発生層）と、セレン（Ｓｅ）にテルル（Ｔｅ）が添加された中間部発生層２２（ａ－Ｓｅ＋Ｔｅ層：第２部分発生層：第２個別発生層）と、セレン（Ｓｅ）にフッ化リチウム（ＬｉＦ）が添加された後部発生層２３（ａ－Ｓｅ＋ＬｉＦ層：第１部分発生層：第３個別発生層）と、を有している。 Both the carrier generation layer 11 and the carrier multiplication layer 12 are formed of a semiconductor layer mainly composed of amorphous selenium (a-Se). The carrier generation layer 11 includes, in order from the front side, a front generation layer 21 in which arsenic (As) is added to selenium (Se) (a-Se + As layer: third partial generation layer: first individual generation layer), selenium. Intermediate part generation layer 22 (a-Se + Te layer: second partial generation layer: second individual generation layer) with tellurium (Te) added to (Se), and lithium fluoride (LiF) added to selenium (Se) A rear generation layer 23 (a-Se + LiF layer: first partial generation layer: third individual generation layer).
　図３は、このように構成されたキャリア発生層１１およびキャリア増倍層１２の成分分布を表している。光電変換層１０を構成するキャリア発生層１１およびキャリア増倍層１２は、その製造プロセスにおいて、真空蒸着法により連続的に形成される。また、真空蒸着法では、セレン（Ｓｅ）用、ヒ素（Ａｓ）用、テルル（Ｔｅ）用およびフッ化リチウム（ＬｉＦ）用の蒸着ノズルがそれぞれ用意されており、セレン（Ｓｅ）用の蒸着ノズルを連続的に駆動させながら、ヒ素（Ａｓ）用、テルル（Ｔｅ）用およびフッ化リチウム（ＬｉＦ）用の蒸着ノズルを選択的に駆動して、キャリア発生層１１およびキャリア増倍層１２が成膜される。 FIG. 3 shows the component distribution of the carrier generation layer 11 and the carrier multiplication layer 12 configured as described above. In the manufacturing process, the carrier generation layer 11 and the carrier multiplication layer 12 constituting the photoelectric conversion layer 10 are continuously formed by a vacuum deposition method. In the vacuum deposition method, vapor deposition nozzles for selenium (Se), arsenic (As), tellurium (Te), and lithium fluoride (LiF) are prepared, respectively. As the carrier generation layer 11 and the carrier multiplication layer 12 are formed, the deposition nozzles for arsenic (As), tellurium (Te), and lithium fluoride (LiF) are selectively driven. Be filmed.
　図３に示すように、第１実施形態の光電変換層１０には、層前端位置Ｆから層後端位置に向かって、膜厚１０００Åのａ－Ｓｅ＋Ａｓ層（前部発生層２１）と、膜厚５００Åのａ－Ｓｅ層と、膜厚２０００Åのａ－Ｓｅ＋Ｔｅ層（中間部発生層２２）と、膜厚５００Åのａ－Ｓｅ層と、膜厚８００Åのａ－Ｓｅ＋ＬｉＦ層（後部発生層２３）と、から成るキャリア発生層１１が成膜されている。また、光電変換層１０には、キャリア発生層１１に続いて、ａ－Ｓｅ層から成るキャリア増倍層１２が成膜されている。そして、光電変換層１０全体の膜厚を４μｍ程度としている。 As shown in FIG. 3, the photoelectric conversion layer 10 of the first embodiment includes an a-Se + As layer (front generation layer 21) having a thickness of 1000 mm from the front layer end position F to the rear layer end position, and a film An a-Se layer having a thickness of 500 mm, an a-Se + Te layer having a thickness of 2000 mm (intermediate generation layer 22), an a-Se layer having a thickness of 500 mm, and an a-Se + LiF layer having a thickness of 800 mm (rear generation layer 23) A carrier generation layer 11 is formed. In the photoelectric conversion layer 10, a carrier multiplication layer 12 made of an a-Se layer is formed after the carrier generation layer 11. And the film thickness of the whole photoelectric converting layer 10 is about 4 micrometers.
　すなわち、ａ－Ｓｅ＋ＬｉＦ層（後部発生層２３）は、キャリア増倍層１２の前方直近に配置されている。また、ａ－Ｓｅ＋Ｔｅ層（中間部発生層２２）は、後部発生層２３の前方となる層前端位置Ｆ側に配置され、ａ－Ｓｅ＋Ａｓ層（前部発生層２１）は、中間部発生層２２の前方となる層前端位置Ｆ側に配置されている。そして、層前端位置Ｆと前部発生層２１の前端位置とが一致している。 That is, the a-Se + LiF layer (rear generation layer 23) is disposed in front of the carrier multiplication layer 12. The a-Se + Te layer (intermediate generation layer 22) is arranged on the front side of the front end position F, which is in front of the rear generation layer 23, and the a-Se + As layer (front generation layer 21) is the intermediate generation layer 22. It is arrange | positioned at the layer front end position F side used as the front. The front layer end position F and the front end position of the front generation layer 21 coincide with each other.
　詳細は後述するが、ａ－Ｓｅ＋ＬｉＦ層（後部発生層２３）は、層前端位置Ｆから０．２μｍ以上３．０μｍ以下の距離、隔てて配置され、且つ膜厚を５００Å以上１０００Å以下とすることが好ましい。第１実施形態の後部発生層２３は、層前端位置Ｆから０．４μｍ隔てて配置され、層厚を８００Åとしている。同様に、ａ－Ｓｅ＋Ｔｅ層（中間部発生層２２）は、層前端位置Ｆから０Å以上の距離、隔てて配置され、且つ膜厚を５００Å以上２．０μｍ以下とすることが好ましい。第１実施形態の中間部発生層２２は、層前端位置Ｆから０．１５μｍ隔てて配置され、層厚を２０００Åとしている。 As will be described in detail later, the a-Se + LiF layer (rear generation layer 23) is disposed at a distance of 0.2 μm or more and 3.0 μm or less from the front end position F of the layer, and has a film thickness of 500 mm or more and 1000 mm or less. Is preferred. The rear generation layer 23 of the first embodiment is disposed at a distance of 0.4 μm from the layer front end position F, and has a layer thickness of 800 mm. Similarly, the a-Se + Te layer (intermediate portion generation layer 22) is preferably arranged at a distance of 0 mm or more from the front end position F of the layer and has a thickness of 500 mm or more and 2.0 μm or less. The intermediate portion generation layer 22 of the first embodiment is disposed at a distance of 0.15 μm from the layer front end position F, and has a layer thickness of 2000 mm.
　また、テルル（Ｔｅ）は、セレンの（Ｓｅ）の不純物としてセレン結晶化の核となり、「白キズ」（白点状欠陥：セレンの一部結晶化により低抵抗となった部分に電界集中が起こり、白く光る現象）の原因となる。このため、中間部発生層２２において、テルルの濃度を低く抑えることが好ましい。すなわち、中間部発生層２２において、テルルの濃度を０．５ｗｔ％以上１０．０ｗｔ％以下とすることが好ましい。第１実施形態の中間部発生層２２では、テルルの濃度を２．５ｗｔ％程度としている。 Tellurium (Te) also becomes a nucleus of selenium crystallization as an impurity of (Se) of selenium, and “white scratches” (white spot-like defects: electric field concentration occurs in a portion where the resistance is reduced by partial crystallization of selenium. Which occurs and causes a white glow). For this reason, it is preferable to keep the tellurium concentration low in the intermediate portion generation layer 22. That is, in the intermediate portion generation layer 22, the tellurium concentration is preferably 0.5 wt% or more and 10.0 wt% or less. In the intermediate generation layer 22 of the first embodiment, the tellurium concentration is about 2.5 wt%.
　ところで、ａ－Ｓｅ＋ＬｉＦ層（後部発生層２３）に添加（ドープ）したフッ化リチウム（ＬｉＦ）は、正孔捕獲準位を形成し、透明電極層１２２からの正孔をブロックする。これにより、暗電流や残像の増加（ノイズ）等が防止されるが、この防止効果は、ＬｉＦが従来技術のように光電変換層１０（キャリア発生層１１）の層前端位置Ｆ側近傍に配置されていなくても、透明電極層１２２と光電変換層１０との界面準位を適切にすることで達成されるものと考えられる。 By the way, lithium fluoride (LiF) added (doped) to the a-Se + LiF layer (rear generation layer 23) forms a hole trap level and blocks holes from the transparent electrode layer 122. As a result, dark current, afterimage increase (noise), and the like are prevented, but this prevention effect is that LiF is arranged in the vicinity of the front end position F of the photoelectric conversion layer 10 (carrier generation layer 11) as in the prior art. Even if it is not done, it is considered to be achieved by making the interface state between the transparent electrode layer 122 and the photoelectric conversion layer 10 appropriate.
　一方で、ＬｉＦは、光侵入方向の前方に対し電界緩和効果を有している。これにより、ａ－Ｓｅ＋ＬｉＦ層（後部発生層２３）を境に、その前方の各層では、アバランシェ倍増が抑えられ光キャリアの発生が主体となる。また、その後方では、強い電界により、発生した光キャリアのアバランシェ倍増が主体となる。すなわち、ａ－Ｓｅ＋ＬｉＦ層（後部発生層２３）の後端から前方にキャリア発生層１１が構成され、後方にキャリア増倍層１２が構成されることになる。 On the other hand, LiF has an electric field relaxation effect in front of the light penetration direction. As a result, avalanche doubling is suppressed and light carrier generation is mainly performed in each of the layers ahead of the a-Se + LiF layer (rear generation layer 23). Behind that, an avalanche doubling of the generated optical carrier is mainly caused by a strong electric field. That is, the carrier generation layer 11 is configured forward from the rear end of the a-Se + LiF layer (rear generation layer 23), and the carrier multiplication layer 12 is configured rearward.
　第１実施形態では、ａ－Ｓｅ＋ＬｉＦ層（後部発生層２３）の前端位置は、層前端位置Ｆから０．４μｍの深さ位置となっている。すなわち、層前端位置Ｆから０．４μｍ隔てた深さ位置に、ａ－Ｓｅ＋ＬｉＦ層（後部発生層２３）が形成されている。一方、光強度が１／ｅ２に減衰する深さである、光の侵入深さは、青色光（Ｂ：４４０ｎｍ）で約０．１μｍ、緑色光（Ｇ：５４０ｎｍ）で約０．２３μｍ、赤色光（Ｒ：６２０ｎｍ）で約２．８μｍである。 In the first embodiment, the front end position of the a-Se + LiF layer (rear generation layer 23) is a depth position of 0.4 μm from the layer front end position F. That is, an a-Se + LiF layer (rear generation layer 23) is formed at a depth position separated by 0.4 μm from the front end position F of the layer. On the other hand, the light penetration depth, which is the depth at which the light intensity is attenuated to 1 / e 2 , is about 0.1 μm for blue light (B: 440 nm), about 0.23 μm for green light (G: 540 nm), It is about 2.8 μm with red light (R: 620 nm).
　すなわち、このキャリア発生層１１では、青色光は元より、緑色光の侵入深さより深い位置にａ－Ｓｅ＋ＬｉＦ層（後部発生層２３）が配置されている。したがって、この光電変換層１０（キャリア発生層１１）では、電界緩和効果により、少なくとも青色光および緑色光の光電変換（光キャリアの発生）が十分に行われることになる。また、このようにして発生した光キャリアが、続くキャリア増倍層１２によりアバランシェ増倍されることになる。 That is, in this carrier generation layer 11, an a-Se + LiF layer (rear generation layer 23) is disposed at a position deeper than the penetration depth of green light from the blue light. Therefore, in the photoelectric conversion layer 10 (carrier generation layer 11), at least blue light and green light photoelectric conversion (generation of optical carriers) is sufficiently performed due to the electric field relaxation effect. Further, the optical carriers generated in this way are avalanche multiplied by the subsequent carrier multiplication layer 12.
　ａ－Ｓｅ＋Ｔｅ層（中間部発生層２２）では、周知のように、セレン（Ｓｅ）に対しバンドギャップの低いテルル（Ｔｅ）が添加（ドープ）されるため、長波長の光（主に赤色光）の光吸収率が向上する。したがって、撮像対象となるＲ・Ｇ・Ｂ各色の光の光電変換が十分に行われ、且つこれによって発生した光キャリアがアバランシェ増倍される。特に、赤色光と共に感度の低下（量子効率の低下）が問題となっていた緑色光の量子効率の向上が達成されることになる。 As is well known, in the a-Se + Te layer (intermediate generation layer 22), tellurium (Te) having a low band gap is added (doped) to selenium (Se). ) Is improved. Therefore, photoelectric conversion of light of R, G, and B colors to be imaged is sufficiently performed, and the optical carriers generated thereby are avalanche multiplied. In particular, an improvement in the quantum efficiency of green light, which has been a problem of a decrease in sensitivity (decrease in quantum efficiency) with red light, is achieved.
　もっとも、テルル（Ｔｅ）は、高温にさらすとセレン（Ｓｅ）中に拡散され、キャリア発生層１１の外（キャリア増倍層１２）に拡散される割合が多くなることが知られている。このため、赤色光の光吸収率を上げても、高温保管環境において赤色光の相対的な感度低下が生じてしまう。したがって、テルル（Ｔｅ）をドープしても、赤色光の感度（量子効率）がさほど変わらないものとなってしまう問題がある。この点において、本実施形態の光電変換層１０では、以下のように、高温保管環境において赤色光の相対的な感度低下が生じないとする、試験結果を得ている。 However, it is known that tellurium (Te) diffuses into selenium (Se) when exposed to high temperatures, and the proportion of tellurium (Te) diffuses out of the carrier generation layer 11 (carrier multiplication layer 12) increases. For this reason, even if the light absorptance of red light is increased, the relative sensitivity of red light is reduced in a high-temperature storage environment. Therefore, there is a problem that even if tellurium (Te) is doped, the sensitivity (quantum efficiency) of red light does not change so much. In this respect, the photoelectric conversion layer 10 of the present embodiment has obtained a test result that the relative sensitivity of red light does not decrease in a high-temperature storage environment as follows.
　図４は、第１実施形態の光電変換層１０（ａ）および上記の特許文献１の光電変換膜（ｂ）につき、高温保管における一次変換効率の試験結果を表したものである。この試験では、アバランシェさせない電圧条件下で、白５０％の光を当て、所定の電流が流れるときの輝度を測定し、感度評価としている。この場合、輝度が低い方が、感度が高いので、リファレンスの輝度／サンプルの輝度で相対値を算出している。横軸を「５０℃の加熱時間（ｈ）」とし、縦軸を「感度相当輝度値」として、高温保管（加速）環境の感度を表している。 FIG. 4 shows the test results of the primary conversion efficiency in high-temperature storage for the photoelectric conversion layer 10 (a) of the first embodiment and the photoelectric conversion film (b) of Patent Document 1 described above. In this test, 50% white light is applied under a voltage condition that does not cause avalanche, and the luminance when a predetermined current flows is measured to evaluate the sensitivity. In this case, since the sensitivity is higher when the luminance is lower, the relative value is calculated by reference luminance / sample luminance. The horizontal axis represents “heating time (h) at 50 ° C.”, and the vertical axis represents “sensitivity equivalent luminance value”, which represents the sensitivity in a high-temperature storage (acceleration) environment.
　図４（ａ）の試験結果によれば、高温保管環境である５０℃１００時間において、青色光（Ｂ）および緑色光（Ｇ）は元より、赤色光（Ｒ）の感度低下（劣化）もほとんど生じなかった。このことは、赤色光の量子効率の向上において、テルル（Ｔｅ）の拡散というマイナス要因に対し、フッ化リチウム（ＬｉＦ）による電界緩和領域の広さ（十分な光電変換）というプラス要因が、大きく寄与しているものと推察される。 According to the test result of FIG. 4 (a), in the high temperature storage environment at 50 ° C. for 100 hours, the blue light (B) and the green light (G) as well as the red light (R) sensitivity decrease (deterioration) Hardly occurred. This is because, in the improvement of the quantum efficiency of red light, the positive factor of the widening of the electric field relaxation region (sufficient photoelectric conversion) by lithium fluoride (LiF) is large against the negative factor of tellurium (Te) diffusion. It is inferred that it has contributed.
　また、緑色光（Ｇ）の感度向上が確認できた。実測値において、５５０ｎｍの波長光（緑色光）の量子効率が１．９倍に向上した。ここでも、フッ化リチウム（ＬｉＦ）による電界緩和領域の広さ（十分な光電変換）が、大きく寄与しているものと推察される。 Also, an improvement in green light (G) sensitivity was confirmed. In the measured value, the quantum efficiency of 550 nm wavelength light (green light) was improved by 1.9 times. Also here, it is assumed that the electric field relaxation region (sufficient photoelectric conversion) by lithium fluoride (LiF) contributes greatly.
　一方、図４（ｂ）の試験結果では、赤色光（Ｒ）の高温保管における感度低下が著しく、また緑色光（Ｇ）の感度向上は確認できなかった。この場合には、フッ化リチウム（ＬｉＦ）の配置位置により、電界緩和領域が狭い（不十分な光電変換）と、赤色光や緑色光の量子効率の向上が抑制されてしまうものと推察される。 On the other hand, in the test result of FIG. 4 (b), the sensitivity of red light (R) was significantly reduced during high-temperature storage, and the sensitivity of green light (G) was not improved. In this case, it is surmised that if the electric field relaxation region is narrow (insufficient photoelectric conversion) due to the arrangement position of lithium fluoride (LiF), the improvement in quantum efficiency of red light or green light is suppressed. .
　なお、図示しないが、この試験において、第１実施形態の光電変換層１０では、「白キズ」の発生が殆どなく、且つ高温保管におる「白キズ」の増加が殆ど起こらなかった。これは、テルル（Ｔｅ）の濃度が低いこと、およびヒ素（Ａｓ）により、セレン（Ｓｅ）の結晶化温度が高くなった（結晶化の抑制）こと、によるものと推察される。 Although not shown, in this test, in the photoelectric conversion layer 10 of the first embodiment, “white scratches” were hardly generated and “white scratches” were hardly increased during high-temperature storage. This is presumably due to the fact that the concentration of tellurium (Te) is low and the crystallization temperature of selenium (Se) is increased (suppression of crystallization) by arsenic (As).
　以上のように、本実施形態の光電変換層１０によれば、キャリア発生層１１におけるａ－Ｓｅ＋ＬｉＦ層（後部発生層２３）を、略緑色光の侵入深さ（である０．２μｍ）よりも深い位置に配置しているため、ＬｉＦによる電界緩和領域を広く（長く）執ることができる。これにより、撮像対象光の光電変換を十分に行ってからアバランシェ増倍させることができ、Ｒ・Ｇ・Ｂ各色光の相対的な量子効率の向上（感度を向上）を達成することができる。特に、従来のものに比して、緑色光の量子効率を向上させることができる。また、高温保管環境における赤色光の量子効率の向上を図ることができ、且つ「白キズ」の発生を抑制することができる。 As described above, according to the photoelectric conversion layer 10 of the present embodiment, the a-Se + LiF layer (rear generation layer 23) in the carrier generation layer 11 is made to have a penetration depth of substantially green light (which is 0.2 μm). Since it is arranged at a deep position, the electric field relaxation region by LiF can be widened (long). Thereby, after sufficient photoelectric conversion of the imaging target light can be performed, avalanche multiplication can be performed, and an improvement in relative quantum efficiency (sensitivity improvement) of each color light of R, G, and B can be achieved. In particular, the quantum efficiency of green light can be improved as compared with the conventional one. In addition, the quantum efficiency of red light in a high-temperature storage environment can be improved, and the occurrence of “white scratches” can be suppressed.
　なお、本実施形態では、中間部発生層２２にテルル（Ｔｅ）を添加するようにしているが、セレン（Ｓｅ）に対しバンドギャップの低いアンチモン（Ｓｂ）、カドミウム（Ｃｄ）およびビスマス（Ｂｉ）等の、１つ以上を添加するようにしてもよい。 In this embodiment, tellurium (Te) is added to the intermediate portion generation layer 22, but antimony (Sb), cadmium (Cd), and bismuth (Bi), which have a lower band gap than selenium (Se). One or more of them may be added.
［第２実施形態］
　次に、図５を参照して、第２実施形態の光電変換層１０Ａについて詳細に説明する。図５の成分分布図に示すように、第２実施形態の光電変換層１０Ａでは、層前端位置Ｆから層後端位置に向かって、膜厚１０００Åのａ－Ｓｅ＋Ａｓ層（前部発生層２１）と、膜厚３０００Åのａ－Ｓｅ層と、膜厚８００Åのａ－Ｓｅ＋ＬｉＦ層（後部発生層２３）と、から成るキャリア発生層１１が成膜されている。この場合も、キャリア増倍層１２を含めた光電変換層１０Ａの膜厚は、４μｍ程度となっている。 [Second Embodiment]
Next, with reference to FIG. 5, the photoelectric conversion layer 10A of 2nd Embodiment is demonstrated in detail. As shown in the component distribution diagram of FIG. 5, in the photoelectric conversion layer 10A of the second embodiment, the a-Se + As layer (front generation layer 21) having a film thickness of 1000 mm from the layer front end position F toward the layer rear end position. The carrier generation layer 11 is formed of an a-Se layer having a thickness of 3000 と and an a-Se + LiF layer (rear generation layer 23) having a thickness of 800 Å. Also in this case, the film thickness of the photoelectric conversion layer 10A including the carrier multiplication layer 12 is about 4 μm.
　そして、ａ－Ｓｅ＋ＬｉＦ層（後部発生層２３）は、キャリア増倍層１２の前方直近に配置され、その前端位置は、層前端位置Ｆから０．４μｍの深さ位置となっている。また、ａ－Ｓｅ＋Ｔｅ層（中間部発生層２２）は省略され、層前端位置Ｆとａ－Ｓｅ＋Ａｓ層（前部発生層２１）の前端位置とが一致している。 The a-Se + LiF layer (rear generation layer 23) is disposed in front of the carrier multiplication layer 12, and the front end position thereof is a depth of 0.4 μm from the layer front end position F. Further, the a-Se + Te layer (intermediate generation layer 22) is omitted, and the front end position F of the layer is coincident with the front end position of the a-Se + As layer (front generation layer 21).
　このような、第２実施形態の光電変換層１０Ａにおいても、キャリア発生層１１におけるａ－Ｓｅ＋ＬｉＦ層（後部発生層２３）を、略緑色光の侵入深さ（である０．２μｍ）よりも深い位置に配置しているため、ＬｉＦによる電界緩和領域を広く（長く）執ることができる。これにより、緑色光の量子効率を向上させることができる。この場合には、実測値において、５５０ｎｍの波長光（緑色光）の量子効率が１．７倍に向上した。また、高温保管環境における赤色光の量子効率の向上を図ることができ、且つ「白キズ」の発生を抑制することができる。 Also in the photoelectric conversion layer 10A of the second embodiment as described above, the a-Se + LiF layer (rear generation layer 23) in the carrier generation layer 11 is deeper than the penetration depth of about green light (which is 0.2 μm). Since it is arranged at a position, the electric field relaxation region by LiF can be widened (long). Thereby, the quantum efficiency of green light can be improved. In this case, in the actual measurement value, the quantum efficiency of 550 nm wavelength light (green light) was improved by 1.7 times. In addition, the quantum efficiency of red light in a high-temperature storage environment can be improved, and the occurrence of “white scratches” can be suppressed.
　なお、特に図示しないが、第２実施形態の光電変換層１０Ａにおいて、後部発生層２３を、テルルを含むａ－Ｓｅ＋Ｔｅ＋ＬｉＦ層としてもよい（変形例）。かかる場合には、第１実施形態の光電変換層１０と同様に、５５０ｎｍの波長光（緑色光）の量子効率が１．９倍に向上するものと思われる。 Although not particularly illustrated, in the photoelectric conversion layer 10A of the second embodiment, the rear generation layer 23 may be an a-Se + Te + LiF layer containing tellurium (modified example). In such a case, like the photoelectric conversion layer 10 of the first embodiment, it is considered that the quantum efficiency of light having a wavelength of 550 nm (green light) is improved by 1.9 times.
［第３実施形態］
　次に、図６を参照して、第３実施形態の光電変換層１０Ｂについて詳細に説明する。図６の成分分布図に示すように、第３実施形態の光電変換層１０Ｂでは、層前端位置Ｆから層後端位置に向かって、膜厚１０００Åのａ－Ｓｅ＋Ａｓ層（前部発生層２１）と、膜厚５００Åのａ－Ｓｅ層と、膜厚２０００Åのａ－Ｓｅ＋Ｔｅ層（中間部発生層２２）と、膜厚５００Åのａ－Ｓｅ層と、膜厚８００Åのａ－Ｓｅ＋Ａｓ＋ＬｉＦ層（後部発生層２３Ｂ）と、から成るキャリア発生層１１が成膜されている。この場合も、キャリア増倍層１２を含めた光電変換層１０Ｂの膜厚は、４μｍ程度となっている。 [Third Embodiment]
Next, with reference to FIG. 6, the photoelectric converting layer 10B of 3rd Embodiment is demonstrated in detail. As shown in the component distribution diagram of FIG. 6, in the photoelectric conversion layer 10B of the third embodiment, an a-Se + As layer (front generation layer 21) having a thickness of 1000 mm from the front end position F to the rear end position of the layer. An a-Se layer with a thickness of 500 mm, an a-Se + Te layer with a thickness of 2000 mm (intermediate generation layer 22), an a-Se layer with a thickness of 500 mm, and an a-Se + As + LiF layer with a thickness of 800 mm (rear generation) And a carrier generation layer 11 comprising a layer 23B). Also in this case, the film thickness of the photoelectric conversion layer 10B including the carrier multiplication layer 12 is about 4 μm.
　そして、ａ－Ｓｅ＋Ａｓ＋ＬｉＦ層（後部発生層２３Ｂ）は、キャリア増倍層１２の前方直近に配置され、その前端位置は、層前端位置Ｆから０．４μｍの深さ位置となっている。また、ａ－Ｓｅ＋Ｔｅ層（中間部発生層２２）は、後部発生層２３Ｂよりも層前端位置Ｆ側に配置され、ａ－Ｓｅ＋Ａｓ層（前部発生層２１）は、中間部発生層２２よりも層前端位置Ｆ側に配置されている。そして、層前端位置Ｆと前部発生層２１の前端位置とが一致している。 The a-Se + As + LiF layer (rear generation layer 23B) is disposed in front of the carrier multiplication layer 12, and the front end position thereof is a depth of 0.4 μm from the front end position F of the layer. Further, the a-Se + Te layer (intermediate generation layer 22) is disposed on the layer front end position F side with respect to the rear generation layer 23B, and the a-Se + As layer (front generation layer 21) is more than the intermediate generation layer 22. It is arrange | positioned at the layer front end position F side. The front layer end position F and the front end position of the front generation layer 21 coincide with each other.
　このような、第３実施形態の光電変換層１０Ｂにおいても、キャリア発生層１１におけるａ－Ｓｅ＋Ａｓ＋ＬｉＦ層（後部発生層２３Ｂ）を、略緑色光の侵入深さ（である０．２μｍ）よりも深い位置に配置しているため、ＬｉＦによる電界緩和領域を広く（長く）執ることができる。これにより、緑色光の量子効率を向上させることができる。この場合には、実測値において、５５０ｎｍの波長光（緑色光）の量子効率が１．７倍に向上した。また、高温保管環境における赤色光の量子効率の向上を図ることができ、且つ「白キズ」の発生を抑制することができる。 Also in the photoelectric conversion layer 10B of the third embodiment as described above, the a-Se + As + LiF layer (rear generation layer 23B) in the carrier generation layer 11 is deeper than the penetration depth of about green light (which is 0.2 μm). Since it is arranged at a position, the electric field relaxation region by LiF can be widened (long). Thereby, the quantum efficiency of green light can be improved. In this case, in the actual measurement value, the quantum efficiency of 550 nm wavelength light (green light) was improved by 1.7 times. In addition, the quantum efficiency of red light in a high-temperature storage environment can be improved, and the occurrence of “white scratches” can be suppressed.
　１０，１０Ａ，１０Ｂ　光電変換層、１１　キャリア発生層、１２　キャリア増倍層、２１　前部発生層、２２　中間部発生層、２３，２３Ｂ　後部発生層、１００　撮像装置、１０１　電子放出基板部、１０２　電子放出素子アレイ、１０２ａ　電子放出素子、１０３　真空空間、１０４　受光基板部、１２１　透光性基板、１２２　透明電極層、１２３　ランディング補助層、Ｆ　層前端位置 10, 10A, 10B photoelectric conversion layer, 11 carrier generation layer, 12 carrier multiplication layer, 21 front generation layer, 22 intermediate generation layer, 23, 23B rear generation layer, 100 imaging device, 101 electron emission substrate unit, 102 Electron emitter array, 102a, electron emitter, 103, vacuum space, 104, light receiving substrate, 121, translucent substrate, 122, transparent electrode layer, 123, landing auxiliary layer, F layer front end position

Claims (9)

  1. 　それぞれがアモルファスセレンを主成分とする、入射した光の光量に応じて光キャリアを生成するキャリア発生層と、生成した光キャリアをアバランシェ倍増させるキャリア増倍層と、を備えた光電変換膜であって、
    　前記キャリア発生層は、光が入射する層前端位置から略緑色光の侵入深さよりも深い位置に、フッ化リチウムが添加された第１部分発生層を有していることを特徴とする光電変換膜。     Each of the photoelectric conversion films includes a carrier generation layer that mainly contains amorphous selenium and generates a photocarrier according to the amount of incident light, and a carrier multiplication layer that doubles the generated optical carrier by avalanche. And
    The carrier generation layer has a first partial generation layer to which lithium fluoride is added at a position deeper than the penetration depth of substantially green light from the front end position of the layer on which light is incident. film.
  2. 　前記第１部分発生層は、前記キャリア増倍層の直近に配置されていることを特徴とする請求項１に記載の光電変換膜。 The photoelectric conversion film according to claim 1, wherein the first partial generation layer is disposed in the immediate vicinity of the carrier multiplication layer.
  3. 　前記第１部分発生層は、前記層前端位置から０．２μｍ以上３．０μｍ以下の距離、隔てて配置されていることを特徴とする請求項１に記載の光電変換膜。 2. The photoelectric conversion film according to claim 1, wherein the first partial generation layer is disposed at a distance of 0.2 μm to 3.0 μm from the front end position of the layer.
  4. 　前記キャリア発生層は、テルル、アンチモン、カドミウムおよびビスマスのうちの、少なくとも１つが添加された第２部分発生層を有し、
    　前記第２部分発生層は、前記第１部分発生層よりも前記層前端位置側に配置されていることを特徴とする請求項１に記載の光電変換膜。     The carrier generation layer has a second partial generation layer to which at least one of tellurium, antimony, cadmium and bismuth is added,
    The photoelectric conversion film according to claim 1, wherein the second partial generation layer is disposed closer to the front end position of the layer than the first partial generation layer.
  5. 　前記第２部分発生層には、テルルが添加され、
    　添加されたテルルの濃度が、０．５ｗｔ％以上１０．０ｗｔ％以下であることを特徴とする請求項４に記載の光電変換膜。     Tellurium is added to the second partial generation layer,
    The photoelectric conversion film according to claim 4, wherein the concentration of the added tellurium is 0.5 wt% or more and 10.0 wt% or less.
  6. 　前記キャリア発生層は、ヒ素が添加された第３部分発生層を有し、
    　前記第３部分発生層は、前記第２部分発生層よりも前記層前端位置側に配置されていることを特徴とする請求項４に記載の光電変換膜。     The carrier generation layer has a third partial generation layer to which arsenic is added,
    The photoelectric conversion film according to claim 4, wherein the third partial generation layer is disposed closer to the front end position of the layer than the second partial generation layer.
  7. 　前記キャリア発生層は、前記第１部分発生層に代えて、
    　前記フッ化リチウムおよびヒ素が添加された第４部分発生層を、有していることを特徴とする請求項４に記載の光電変換膜。     The carrier generation layer is replaced with the first partial generation layer,
    The photoelectric conversion film according to claim 4, further comprising a fourth partial generation layer to which the lithium fluoride and arsenic are added.
  8. 　光が入射する側から第１個別発生層、第２個別発生層および第３個別発生層を有し、それぞれがアモルファスセレンを主成分とするキャリア発生層を備えた光電変換膜であって、
    　前記第１個別発生層には、前記アモルファスセレンにヒ素が添加され、
    　前記第２個別発生層には、前記アモルファスセレンにテルルが添加され、
    　前記第３個別発生層には、前記アモルファスセレンにフッ化リチウムが添加されていることを特徴とする光電変換膜。     A photoelectric conversion film including a first individual generation layer, a second individual generation layer, and a third individual generation layer from a light incident side, each including a carrier generation layer mainly composed of amorphous selenium;
    In the first individual generation layer, arsenic is added to the amorphous selenium,
    In the second individual generation layer, tellurium is added to the amorphous selenium,
    The photoelectric conversion film according to claim 3, wherein lithium fluoride is added to the amorphous selenium in the third individual generation layer.
  9. 　透光性基板、透明電極および請求項１ないし８のいずれかに記載の光電変換膜を有する受光基板部と、
    　真空空間を存して前記受光基板部に対面し、前記光電変換膜に向かって電子を放出する電子放出素子アレイ、および前記電子放出素子アレイを駆動する駆動回路を有する電子放出基板部と、を備えたことを特徴とする撮像装置。     A light-receiving substrate having a light-transmitting substrate, a transparent electrode, and the photoelectric conversion film according to claim 1;
    An electron-emitting device array that faces the light-receiving substrate portion in a vacuum space and emits electrons toward the photoelectric conversion film, and an electron-emitting substrate portion having a drive circuit that drives the electron-emitting device array, An image pickup apparatus comprising:
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