FEATURES OF CZ GROWTH OF THE LARGE SIZE LOW DISLOCATION GERMANIUM CRYSTALS

Cz growth of large diameter Ge single crystals has been studied. The crystals have been grown from the melt with various shapes of the crystallization front. The formation of dislocation low angle boundaries (LAB) has been analyzed. We have analyzed the formation of LAB in the as−grown Ge crystals taking into account the actual distribution of thermal tension in the crystal in the presence of radial and axial heat sinks. The behavior LAB−forming dislocations in the thermal tension field has been considered. We have analyzed the migration of these dislocations in the sliding planes and specified possible dislocation aggregation planes. The best results have been obtained for crystals in which the crystallization front was slightly concave towards the crystal. Thus, we have observed a uniform distribution of dislocations. As a result of the analysis we have determined the thermal conditions for growth of LAB free ingots. Experiments confirmed the compliance of model representations with real crystal growth conditions, and we have obtained Ge single crystals with a diameter of100 mmand more, with a low dislocations density and free from LAB.

1. Alferov Zh. I., Andreev V. M, Rumyantsev V. D. Trends and Perspectives of Solar Photovoltaics. Fizika i tekhnika poluprovodnikov = Semiconductors, 2004, vol. 38, no. 8, pp. 937—948. (In Russ.).

2. Naumov A. V. World market of germanium and its prospects. Russian Journal of Non−Ferrous Metals. 2007, vol. 48, no. 4, pp. 265—272.

3. de Kock A. J. R. Microdefects in dislocation−free silicon crystals. Phil. Res. Repts Suppl. 1973, no. 1, р. 1—105.

4. Vogel F. L. Dislocations in low−angle boundaries in germanium. Acta Mettalurgia. 1955, vol. 3, pp. 245—248.

5. Dash W. S. Growth of silicon crystals free from dislocations. J. Appl. Phys. 1959, vol. 30, рp. 459—474.

6. Voronov I. N., Smirnov V. A., Eidenzon A. M. Analysis of the conditions of occurrence of low−angle boundaries in the process of growing silicon single crystals by the CZ−method. Kristallografiya = Crystallography Reports, 1979, vol. 24, no. 6, pp. 1259—1265. (In Russ.)

7. Anoshin K. E., Gindin P. D., Semenov S. K., Shubin A. V. The Technology of Growth of big diameter Germanium CZ−crystals with Low−dislocation density. Integral, 2013, no. 5–6, pp. 12—14. (In Russ.)

8. Ellis S. G. Surface studies on Single−Crystal Germanium. J. Applied Phys. 1957, vol. 28, no. 11, pp. 1262—1269.

9. Roth M. Azoulay M., Gafni G. Crystal−melt interface shape of Czochralski−growth large diameter germanium crystals. J. Crystal Growth, 1990, vol. 99, pp. 670—678.

10. Puzanov N. I., Eidenzon A. M. The formation of dislocations in growing dislocation−free crystal Si. Neorganicheskie materialy = Inorganic materials. 1996, vol. 32, no. 5, pp. 519—525. (In Russ.).

11. Eidenzon A. M. Terms of occurrence of dislocations in the original dislocation−free silicon single crystals grown from the melt. Izv. AN SSSR, ser. fizicheskaya, 1980, vol. 44, no. 2, pp. 312—328. (In Russ.).

12. Oksanych A. P., Malevanny V. V. Mathematical modelling of geometry of a heat unit and development of experimental unit for growing of germanium ingots of diameter of 100 mm by the Czochralski method. Novitnti materiali i nanotehnologii. Vestn. KrNU im. Myhayla Ostrogradskogo = Transactions of Kremenchuk Mykhailo Ostrohradskyi National University. 2012, no. 6(77), pp. 11—16 (In Russ.).

13. Bogomaz A. V., Kritskaya T. V., Karpenko A. V. Thermal unit germanium growth chamber installation method of growing large crystals submersible shaper. Metallurgiya: naukovi pratsi ZDIA = Metallurgy, 2010, vol. 20, pp. 89—95 (In Russ.).

14. Geydt I. S., Kravtsova E. D., Podkopayev O. I. Effect of the power of a heater shield on the heat and mass transfer when producing germanium crystals with low dislocation density by using the Czochralski process. Novyi universitet. Ser.: Tekhnicheskie nauki = New University. Technical science. 2013, no. 11–12, pp. 54—60. (In Russ.).

15. Alimov, O. M. Anoshin K. E., Ezhlov V. S. Ustroistvo dlya vyrashchivaniya monokristallov iz rasplava metodom Chokhral’skogo [A device for growing single crystals from the melt by the CZ−method]. Patent 135650 (RF), 2013. (In Russ.)