The effect of contact phenomena on the measurement of electrical conductivity of reduced lithium niobate

Lithium niobate (LN) is a ferroelectric material with a wide range of applications in optics and acoustics. Annealing of LN crystals in an oxygen-free environment leads to the appearance of black coloration and the concomitant increase in electrical conductivity due to chemical reduction. The literature presents many works on the study of the electrophysical properties of reduced crystals of LN, however, the contact phenomena arising during the measurement of electrical conductivity, as well as the interaction of the electrode material with the samples under study, are practically ignored. In this paper, the effect of chromium and indium tin oxide (ITO) electrodes on the results of measurements at room temperature of electrophysical parameters of LN samples recovered at 1100 °C is investigated. It was found that significant non-linearities in the voltage characteristics (I-V curve.) at voltages less than 5V do not allow to obtain the correct values of the resistivity of NL. This leads to the need to carry out measurements at higher voltages. By the method of pulse spectroscopy, it is shown that capacitances, including those formed, probably, in the contact areas, have a strong influence on the measurement results. It is shown that the results obtained are adequately described by a model assuming the presence of contactless tanks connected in parallel to the sample’s own capacity. A possible mechanism for the formation of such containers is described, and an assumption is made about the existence of a significant density of electronic states at the “electrode - sample” interface capable of capturing charge carriers, and with increasing annealing time, the concentration of captured carriers increases.

1. Kubasov I.V., Kislyuk A.M., Turutin A.V., Bykov A.S., Kiselev D.A., Temirov A.A., Zhukov R.N., Sobolev N.A., Malinkovich M.D., Parkhomenko Y.N. Low-frequency vibration sensor with a sub-nm sensitivity using a bidomain lithium niobate crystal. Sensors (Basel). 2019; 19(3): 614. https://doi.org/10.3390/s19030614

2. Turutin A.V., Vidal J.V., Kubasov I.V., Kislyuk A.M., MalinkovichM.D., Parkhomenko Y.N., Kobeleva S.P., Pakhomov O.V., Kholkin A.L., Sobolev N.A. Magnetoelectric metglas/bidomain y + 140°-cut lithium niobate composite for sensing fT magnetic fields. Appl. Kubasov I.V, Kislyuk A.M., Turutin A.V, Malinkovich M.D., Parkhomenko Y.N. Bidomain Ferroelectric Crystals: Properties and Prospects of Application. Phys. Lett. 2018; 112(26): 262906. https://doi.org/10.1063/1.5038014

3. Kubasov I.V., Kislyuk A.M., Ilina T.S., Shportenko A.S., Kiselev D.A., Turutin A.V., Temirov A.A., Malinkovich M.D., Parkhomenko Y.N. Conductivity and memristive behavior of completely charged domain walls in reduced bidomain lithium niobate. J. Mater. Chem. C. 2021; 9(43). https://doi.org/10.1039/d1tc04170C

4. Kubasov I.V., Kislyuk A.M., Turutin A.V., Malinkovich M.D., Parkhomenko Yu.N. Bidomain ferroelectric crystals: properties and prospects of application. Izvestiya Vysshikh Uchebnykh Zavedenii. Materialy Elektronnoi Tekhniki = Materials of Electronics Engineering. 2020; 23(1): 5—56. (In Russ.). https://doi.org/10.17073/1609-3577-2020-1-5-56

5. Standifer E.M., Jundt D.H., Norwood R.G., Bordui P.F. Chemically reduced lithium niobate single crystals: processing, properties and improvements in SAW device fabrication and performance. In: Proc. IEEE International Frequency Control Symposium. 1998: 470—472. https://doi.org/10.1109/FREQ.1998.717939

6. Jen S., Bobkowski R. Black lithium niobate SAW device fabrication and performance evaluation. In: Proc. IEEE Ultrasonics Symposium. 2000: 269—273. https://doi.org/10.1109/ultsym.2000.922554

7. Kuzminov Yu.S. Electro-optical and nonlinear-optical lithium niobate crystal: monograph. Moscow: Nauka; 1987. 264 p. (In Russ.)

8. Palatnikov M.N., Sandler V.A., Sidorov N.V., Makarova O.V., Manukovskaya D.V. Conditions of application of LiNbO3 based piezoelectric resonators at high temperatures. Phys. Lett. A. 2020; 384(14): 126289. https://doi.org/10.1016/j.physleta.2020.126289

9. Yatsenko A.V., Pritulenko A.S., Yagupov S.V., Sugak D.Y., Sol’skii I.M. Investigation of the stability of electrical properties of reduced LiNbO3 crystals. Tech. Phys. 2017; 62(7): 1065—1068. https://doi.org/10.1134/s1063784217070271

10. Dhar A., Singh N., Singh R.K., Singh R. Low temperature dc electrical conduction in reduced lithium niobate single crystals. J. Phys. Chem. Solids. 2013; 74(1): 146—151. https://doi.org/10.1016/j.jpcs.2012.08.011

11. Volk T., Wöhlecke M. Lithium niobate: defects, photorefraction and ferroelectric switching. Berlin: Springer Science & Business Media; 2008. 249 p.

12. Singh K. Electrical conductivity of non-stoichiometric LiNbO3 single crystals. Ferroelectrics. 2004; 306(1): 79—92. https://doi.org/10.1080/00150190490457348

13. Yatsenko A.V., Yevdokimov S.V., Pritulenko A.S., Sugak D.Y., Solskii I.M. Electrical properties of LiNbO3 crystals reduced in a hydrogen atmosphere. Phys. Solid State. 2012; 54(11): 2231—2235. https://doi.org/10.1134/S1063783412110339

14. Bordui P.F., Jundt D.H., Standifer E.M., Norwood R.G., Sawin R.L., Galipeau J.D. Chemically reduced lithium niobate single crystals: Processing, properties and improved surface acoustic wave device fabrication and performance. J. Appl. Phys. 1999; 85(7): 3766—3769. https://doi.org/10.1063/1.369775

15. Yatsenko A.V., Pritulenko A.S., Yevdokimov S.V., Sugak D.Y., Syvorotka I.I., Suhak Y.D., Solskii I.M., Vakiv M.M. The influence of annealing in saturated water vapor on LiNbO3 crystals optical and electrical properties. Solid State Phenomena. 2015; 230: 233—237. https://doi.org/10.4028/www.scientific.net/SSP.230.233

16. Akhmadullin I.Sh., Golenishchev-Kutuzov V.A., Migachev S.A., Mironov S.P. Low-temperature electrical conductivity of lithium niobate crystals of congruent composition. Fizika tverdogo tela. 1998; 40(7): 1307—1309. (In Russ.)

17. Schröder M., Haußmann A., Thiessen A., Soergel E., Woike T., Eng L.M. Conducting domain walls in lithium niobate single crystals. Adv. Funct. Mater. 2012; 22(18): 3936—3944. https://doi.org/10.1002/adfm.201201174

18. Sanna S., Schmidt W.G. LiNbO3 surfaces from a microscopic perspective. J. Phys.: Condens. Matter. 2017; 29(41): 413001. https://doi.org/10.1088/1361-648X/aa818d

19. Esin A.A., Akhmatkhanov A.R., Shur V.Y. The electronic conductivity in single crystals of lithium niobate and lithium tantalate family. Ferroelectrics. 2016; 496(1): 102—109. https://doi.org/10.1080/00150193.2016.1157438

20. Wang C., Sun J., Ni W., Yue B., Hong F., Liu H., Cheng Z. Tuning oxygen vacancy in LiNbO3 single crystals for prominent memristive and dielectric behaviors. J. Am. Ceram. Soc. 2019; 102(11): 6705—6712. https://doi.org/10.1111/jace.16522

21. Blistanov A.A., Kozlova N.S., Geras’kin V.V. The phenomenon of electrochemical self-decomposition in polar dielectrics. Ferroelectrics. 1997; 198(1-4): 61—66. https://doi.org/10.1080/00150199708228338

22. Kozlova N.S., Zabelina E.V., Bykova M.B., Kozlova A.P. Features of manifestation of surface electrochemical processes in ferroelectric crystals with low-temperature phase transitions. Izvestiya Vysshikh Uchebnykh Zavedenii. Materialy Elektronnoi Tekhniki = Materials of Electronics Engineering. 2018; 21(3): 146—155. (In Russ.). https://doi.org/10.17073/1609-3577-2018-3-146-155

23. Buzanov O.A., Zabelina E.V., Kozlova N.S., Sagalova T.B. Near-electrode processes in lanthanum-gallium tantalate crystals. Crystallogr. Rep. 2008; 53(5): 853—857. https://doi.org/10.1134/S1063774508050210

24. Kozlova N.S., Zabelina E.V., Bykova M.B., Kozlova A.P. Features of the manifestation of surface electrochemical processes in ferroelectric crystals with low-temperature phase transitions. Russ. Microelectron. 2019; 48(8): 545—552. https://doi.org/10.1134/S1063739719080092

25. Emelyanova Yu.V., Morozova M.V., Mikhailovskaya Z.A., Buyanova E.S. Impedance spectroscopy: theory and application. Yekaterinburg: Ural Federal University named after the first President of Russia B.N. Yeltsin; 2017. 156 p. (In Russ.)