Planar X-ray detector

• US 20010008271A1
• Filed: 01/10/2001
• Published: 07/19/2001
• Est. Priority Date: 01/12/2000
• Status: Active Grant

• Current Assignee: Kabushiki Kaisha Toshiba (Toshiba Corporation)
• Original Assignee: Kabushiki Kaisha Toshiba (Toshiba Corporation)
• Inventors: Tanaka, Manabu, Sugawara, Yasuhiro, Kinno, Akira, Ikeda, Mitsushi, Atsuta, Masaki
• Granted Patent: US 6,507,026 B2
• Time in Patent Office: Days
• US Class Current: 250/370.09
• CPC Class Codes: H01L 27/14658 X-ray, gamma-ray or corpuscular radiation imagers measuring X-, gamma- or corpuscular radiation G01T1/00
• CPC Class Codes: H01L 27/14659 Direct radiation imagers structures
• CPC Class Codes: H10K 30/10 comprising heterojunctions between organic semiconductors and inorganic semiconductors
• CPC Class Codes: H10K 30/35 comprising inorganic nanostructures, e.g. CdSe nanoparticles
• CPC Class Codes: H10K 30/451 comprising a metal-semiconductor-metal [m-s-m] structure
• CPC Class Codes: H10K 39/32 Organic image sensors
• CPC Class Codes: H10K 85/114 Poly-phenylenevinylene; Derivatives thereof
• CPC Class Codes: H10K 85/324 comprising aluminium, e.g. Alq3
• CPC Class Codes: H10K 85/351 Metal complexes comprising lanthanides or actinides, e.g. comprising europium
• CPC Class Codes: H10K 85/615 Polycyclic condensed aromatic hydrocarbons, e.g. anthracene
• CPC Class Codes: H10K 85/631 Amine compounds having at least two aryl rest on at least one amine-nitrogen atom, e.g. triphenylamine
• CPC Class Codes: H10K 85/6565 Oxadiazole compounds
• CPC Class Codes: Y02E 10/549 Organic PV cells

Abstract

A planar X-ray detector has an X-ray charge conversion film converting an incident X-ray into electric charges, pixel electrodes provided on the X-ray charge conversion film corresponding to respective pixels arranged in an array, switching elements connected to the respective pixel electrodes, signal lines, each of which is connected to a column of switching elements, scanning lines, each of which transmits driving signals to a raw of switching elements, and a common electrode provided on the surface of the X-ray charge conversion film opposite to the surface on which the pixel electrodes are provided. The X-ray charge conversion film contains an X-ray sensitive material made of inorganic semiconductor particles, and a carrier transport material made of an organic semiconductor.

Claims

1. A planar X-ray detector, comprising:

an X-ray charge conversion film converting an incident X-ray into electric charges;

pixel electrodes provided on the X-ray charge conversion film corresponding to respective pixels arranged in an array;

switching elements connected to the respective pixel electrodes;

signal lines, each of which is connected to a column of switching elements;

scanning lines, each of which transmits driving signals to a raw of switching elements; and

a common electrode provided on the surface of the X-ray charge conversion film opposite to the surface on which the pixel electrodes are provided;

wherein the X-ray charge conversion film contains an X-ray sensitive material comprising inorganic semiconductor particles, and a carrier transport material comprising an organic semiconductor.

2. The planar X-ray detector according to

claim 1

, wherein the X-ray sensitive material is made of at least one material selected from the group consisting of PbI₂, CsI, NaI, HgI₂, CdS, Hg₂IN, HgBrN, Mn₃HgN, HgI₂BN, PbN₂, Pb(N₃)₂, GaAs, CdTe, PbTe, Te and Se.

3. The planar X-ray detector according to

claim 1

, wherein the carrier transport material represents hole or electron mobility of at least 1×

10<sup>−

7</sup> cm²/V·

sec.

4. The planar X-ray detector according to

claim 1

, wherein the carrier transport material is made of at least one material selected from the group consisting of tris(8-quinolinolato)aluminum, N,N-diphenyl-N,N-di(m-tolyl)benzidine, polyparaphenylene vinylene, polyalkyl thiophene, polyvinyl carbazole, triphenylene, a liquid crystal, metal phthalocyanine and 4-(dicyanomethylene)-2-methyl-6-(p-dimethylaminostyryl)-4H-pyran.

5. The planar X-ray detector according to

claim 1

, wherein the carrier transport material has LUMO of 2.4 eV or more and HOMO of 6.5 eV or less.

6. The planar X-ray detector according to

claim 1

, wherein the X-ray sensitive material contains inorganic semiconductor particles having a relatively large particle size and inorganic semiconductor particles having a relatively small particle size.

7. The planar X-ray detector according to

claim 1

, wherein the density of the X-ray sensitive material in the X-ray charge conversion film is relatively high on the side of the common electrode and is relatively low on the side of the pixel electrodes.

8. The planar X-ray detector according to

claim 1

, wherein the X-ray charge conversion film further comprises a binder.

9. The planar X-ray detector according to

claim 8

, wherein the mixing ratio of the carrier transport material to the binder is relatively high on the side of the common electrode and is relatively low on the side of the pixel electrodes.

10. The planar X-ray detector according to

claim 8

, wherein the particles of the X-ray sensitive material are covered with a second carrier transport material consisting of an organic semiconductor, and wherein the energy level of the second carrier transport material is intermediate between the energy level of the X-ray sensitive material and the energy level of the carrier transport material mixed with the binder.

11. The planar X-ray detector according to

claim 1

, further comprising:

a hole transport layer provided on one side of the X-ray charge conversion film; and

an electron transport layer provided on the other side of the X-ray charge conversion film.

12. The planar X-ray detector according to

claim 11

, wherein the electron transport layer is formed of at least one material selected from the group consisting of an oxadiazole derivative, tris(8-quinolinolato)aluminum, n-type Si and n-type GaAs.

13. The planar X-ray detector according to

claim 11

, wherein the hole transport layer is formed of at least one material selected from the group consisting of N,N-diphenyl-N,N-di(m-tolyl)benzidtine, diamine, p-type Si, p-type GaAs, polyparaphenylene vinylene and 4-(dicyanomethylene)-2-methyl-6-(p-dimethylaminostyryl)-4H-pyran.

14. The planar X-ray detector according to

claim 1

, further comprising capacitors accumulating carriers generated in the X-ray charge conversion film for respective pixels, each capacitor being connected to the switching element in each pixel.

15. A planar X-ray detector comprising:

a pair of electrodes, and

an X-ray charge conversion film disposed between the electrodes, the film containing a mixture of inorganic semiconductor particles sensitive to an X-ray and a carrier transport material.

16. The planar X-ray detector according to

claim 15

, wherein the inorganic semiconductor particles are made of at least one material selected from the group consisting of PbI₂, CsI, NaI, HgI₂, CdS, Hg₂IN, HgBrN, Mn₃HgN, HgI₂BN, PbN₂, Pb(N₃)₂, GaAs, CdTe, PbTe, Te and Se.

17. The planar X-ray detector according to

claim 15

, wherein the carrier transport material is made of at least one material selected from the group consisting of tris(8-quinolinolato)aluminum, N,N-diphenyl-N,N-di(m-tolyl)benzidine, polyparaphenylene vinylene, polyalkyl thiophene, polyvinyl carbazole, triphenylene, a liquid crystal, metal phthalocyanine and 4-(dicyanomethylene)-2-methyl-6-(p-dimethylaminostyryl)-4H-pyran.

18. The planar X-ray detector according to

claim 15

, wherein the inorganic semiconductor particles have two different particle size.

19. The planar X-ray detector according to

claim 15

, further comprising a capacitor connected to one of the electrodes, and a protective thin film transistor connected to one of the electrodes.

20. The planar X-ray detector according to

claim 15

, further comprising a switching transistor connected to one of the electrodes, and a voltage source connected to the other one of the electrodes.

21. The planar X-ray detector according to

claim 15

, further comprising a hole transport layer disposed between the X-ray charge conversion film and one of the electrodes, and an electron transport layer disposed between the X-ray charge conversion film and the other one of the electrodes.