Yu.M. Dikaev – Ph.D. (Phys.-Math.), Research Scientist, Kotelnikov Institute of Radioengineering and Electronics  of Russian Academy of Sciences, Fryazino branch (Kotelnikov FIRE RAS)

E-mail: ymd217@ire216.msk.su

A.A. Kudryashov – Research Scientist, Kotelnikov Institute of Radioengineering and Electronics of Russian Academy of Sciences, Fryazino branch (Kotelnikov FIRE RAS)

e-mail: aka217@ire216.msk.su

A.G. Petrov – Research Scientist, Kotelnikov Institute of Radioengineering and Electronics of Russian Academy of Sciences, Fryazino branch (Kotelnikov FIRE RAS)

E-mail: agp217@ire216.msk.su

Detectors on GaAs and CdZnTe find application in X-ray medical diagnostics. The photovoltaic X-ray detector developed by us on the basis of epitaxial structure of p+-n-n'-n + – GaAs efficiently works without bias voltage at ambient temperature. Epitaxial structures were grown up by method of a gas-phase epitaxy on n substrates doped by silicon + – GaAs (n≈1018 cm–3). They consisted of three layers: the high layer of p+-GaAs (p+ ≈ 1018 cm-3) 1-2 microns thick, n layer – GaAs (n~1011–1013 cm–3) 60-100 microns thick and the buffer layer of n’ – GaAs (n’≈5∙1017 cm–3) 2-3 microns thick. For a more hard X-ray radiation the most perspective material for manufacture of detectors is CdZnTe. Affects quality of detectors both manufacturing techniques of detectors, and technology of cultivation of monocrystals CdZnTe: method and conditions of body height, doping various impurity and also purity of the initial Cd, Zn and Te components. For the purpose of use of these detectors researches of some of their main electrophysical properties and characteristic of the manufactured multielement linear detectors for creation of digital x-ray films of the irradiated biological objects are given in biomedicine in this work.Detector properties of structures were measured: dependence of sensitivity of the detector on effective energy in the range of 7-120 keV an incident X-ray radiation and from a yaw angle of beams. The maximum sensitivity of the detector is reached at energy of photons in 35 keV and yaw angles of the close to zero. Epitaxial GaAs the detector, having the fissile area of a quantum absorption of hard rays in n – GaAs a layer less than 100 microns thick, concedes in sensitivity of CdZnTe to the detector. Sensitization of GaAs of the detector turns out at inclined falling of beams. On the example of two effective energies more significant increase in sensitivity is reached for 56 keV (by 4 times), than for 25 keV (less than 2 times) at decrease of a yaw angle from 90 degrees to 10. It reaches shift of the maximum sensitivity of the detector from 35 keV to the more hard area of a X-ray radiation. Thus, the detector with a thin fissile layer of absorption of photons can be used for filing of a more hard X-ray radiation when it poorly reacts at normal falling of photons. Perspective material for detectors in the field of filing of hard rays (higher than 35 keV) is CdZnTe. The sensitivity of the detector Cd0,9Zn0,1Te is brought to a X-ray radiation depending on effective energy for two bias voltages. Very high sensitivity appeared at the manufactured detector with application of deep cleaning of starting materials. In CdZnTe the detector the field of absorption of energy of photons of hard rays is located between contacts with potentials of the enclosed external voltage (from 100 volts and above) and is defined by the crystal sizes from several millimeters and more. The photo effect in the detector depends on the direction of the enclosed electric field. In the range of the measured values of effective energy 28-72 keV the sensitivity of the detector CdZnTe is 1.5 – 2 times higher when Roentgen rays are perpendicular to the enclosed electric field, than at the parallel direction. By results of a research of structures GaAs multielement lines of detectors were made. The detector range CdZnTe having higher sensitivity is offered and investigated. The X-ray detectors developed and manufactured by us on the basis of GaAs and CdZnTe were used in fluorographic and biological researches. X-ray images about use of our multichannel detectors are submitted. On the basis of a research and comparisons of detectors on the basis of GaAs and CdZnTe came to a conclusion of the recommendation of their use in biomedicine.

1. Ahmadullin R.A., Dvoryankin V.F., Dvoryankina G.G., Dikaev YU.M., Ermakov M.G., Ermakova O.N., Krikunov A.I., Kudryashov A.A., Petrov A.G., Telegin A.A. Linejnyj detektor registracii rentgenovskih izobrazhenij // Pribory i tekhnika eksperimenta. 2002. № 4. S. 166–167.
2. Dvoryankin V.F., Dikaev YU.M., Kudryashov A.A., Petrov A.G., Telegin A.A. Mnogoelementnyj panoramnyj rentgenovskij detektor na baze arsenida galliya // Kontrol'. Diagnostika. 2016. № 7. S. 53–55.
3. Dvoryankin V.F., Dvoryankina G.G., Dikaev Yu.M., Ermakov M.G., Kudryashov A.A., Petrov A.G., Telegin A.A. Photovoltaic GaAs Detectors for Digital X-Ray Imaging // Mammography – Resent Advances. Rijeka: Printed in Croatia. 2012. P. 341–353.
4. McGregor D.S., Hermon H. Room temperature compound semiconductor radiation detectors // Nuclear Instruments and Methods in Physics Research Section A. 1997. V. A395. Is. 1. P. 101–124.
5. Battar C.M. GaAs detectors – A review // Nuclear Instruments and Methods in Physics Research Section A. 1997. V. A395. Is. 1. P. 1–8.
6. Dvoryankin V.F., Dikaev YU.M., Kudryashov A.A. Issledovanie svojstv fotovol'taicheskih detektorov rentgenovskogo izlucheniya na osnove epitaksial'nyh struktur GaAs // ZHurnal tekhnicheskoj fiziki. 2004. T. 74. № 6. S. 126–128.
7. Dvoryankin V.F., Dvoryankina G.G., Dikaev YU.M., Ermakov M.G., Ermakova O.N., Kudryashov A.A., Petrov A.G., Telegin A.A. Harakteristiki fotovol'taicheskogo rentgenovskogo detektora na osnove epitaksial'noj struktury arsenida galliya // ZHurnal tekhnicheskoj fiziki. 2007. T. 77. № 10. S. 121–124.
8. Dvoryankin V.F., Dvoryankina G.G., Kudryashov A.A., Petrov A.G., Golyshev V.D., Bykova S.V. Issledovanie chuvstvitel'nosti detektorov na osnove Cd0,9Zn0,1Te k rentgenovskomu izlucheniyu // ZHurnal tekhnicheskoj fiziki. 2010. T. 80. V. 2. S. 149–151.
9. Bosiers J., Vermeiren J., Sevenhaus J. High Resolution Linear Arrays // SPIE Proceedings. 1995. V. 591. P. 67–70.
10. Dvoryankin V.F., Dvoryankina G.G., Dikaev YU.M., Ermakov M.G., Kudryashov A.A., Petrov A.G., Telegin A.A. Fotovol'taicheskie rentgenovskie detektory na osnove epitaksial'nyh struktur GaAs // Pribory i tekhnika eksperimenta. 2013. № 1. S. 97–102.
11. Kozlova O.G. Rost kristallov. M.: Isd-vo MGU. 1967. S. 238.
12. IvanovYU.M., Lejbov V.A., Pavlova G.S. Vliyanie kompleksnoj ochistki na podvizhnost' i vremya zhizni nositelej zaryada v telluride kadmiya // Neorganicheskie materialy. 1990. T. 26. № 1. S. 66–68.
13. Arkad'eva E.N., Karpenko V.P., Maslova L.V., Matveev O.A., Ryvkin S.M., Terent'ev A.I. O vozmozhnosti ispol'zovaniya tellurida kadmiya dlya detektirovaniya impul'snogo rentgenovskogo izlucheniya v medicinskih tomografah // ZHurnal tekhnicheskoj fiziki. 1981. T. 51. № 9. S. 1933–1937.
14. Dvoryankin V.F., Dvoryankina G.G., Dikaev YU.M., Kudryashov A.A., Petrov A.G., Telegin A.A. Mnogopiksel'nyj linejnyj detektor rentgenovskogo izlucheniya na osnove monokristallov CdZnTe // Pribory mikroelektroniki. 2015. T. 44. № 4. S. 1–3.