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The liquidus curve and crystal growth in the Hg:Te system
Journal of Crystal Growth 8 (1971) 221—222 © North-Holland Publishing Co.
THE LIQULDUS CURVE AND CRYSTAL GROWTH IN THE Hg:Te SYSTEM
E. Z. DZIUBA Institute of Physics, Polish Academy of Sciences, Hoza 69, Warsaw, Poland
Received 19 December 1969; revised manuscript received 24 August 1970
The liquidus curve for the mercury telluride binary system is given for atomic concentrations of tellurium from 0.1% to 12°c.The form of the crystal which has been obtained from the solution depends on its concentration.
Semiconducting compounds can be crystallized using solutions of its components in different solvents by controlling the temperature or pressure dependence of the solubility of its components. Good quality crystals can be grown in forms of plates, needles and bulk. Mercury telluride is one of A2B6 semiconducting compounds which has a zinc blende lattice. Crystals of this material have been obtained by Bridgman method’) 2) and and in recent times also using sublimation solution3 5) methods. Theby best quality of the mercury telluride crystals was obtained by using the solution method, Various mixtures of three times destilled Hg and zone refined Te have been introduced in a glass tube of approximately 10 mm in diameter and 100 mm in length and connected to a vacuum system through a (a)
Fig. 1.
(b)
cooling-tube. Before the sealing off’), the tube was heated to remove gases dissolved in the liquid mercury and evacuated to 10 ~Torr. The tube, prepared in this way, retains a vacuum better than 10 2 Torr. Crystallization occurs during the lowering of the temperature with a rate of cooling of 0.5 C/hr, using a solution with a concentration of Te up to x 0.02 (ref.whole 3). Asurface single of crystal of aboutConcentrations 50 jim thick covers the the solution. larger than x = 0.03 Te did not produce one large plate single crystal, even at cooling rates lower than 0.5 °C/h.Instead, a large number of monocrystals having an irregular terrace form with dimentions up to 1 cm2 are obtained3’4) (fig. 2). An explanation for the growth of thin plate crystals, is given by analysing the liquidus of the Hg-Te system (a)
Mercury telluride crystals obtained from the solution ha~ing(a) high and (b) low concentrations ofTe.
221
222
E. Z. DZIUBA
There are no difficulties in removing the crystals from the tube when the crystals have terrace forms. The liquid mercury is removed from the surface of the crystal by etching in HNO3 and in a solution of 1 % Br in methyl alcohol. It is difficult to remove the SOpm thin plates from the tube. Before opening it is necessary to put the tube into a bath with the mercury. If the levels of the mercury inside and outside of the tube are the same, it is possible to open the glass tube without turbulent movement of the mercury in the tube. xz,’mci~
Fig. 2.
10
The liquidus curve in Hg:Te binary system.
shown in fig. 26). A change of the slope, of the liquidus line occurs at x = 0.03. The probability of the growth of many crystals during the crystallization process is larger when the solution has a high concentration of tellurium, whereas low concentrations favor the growth of a single crystal on the surface. The quality of the thin plate crystals grown from 7). the 0.02 Te solution of Te was investigated by Litwin X-ray analysis df a crystal, using the pseudo-Kossel lines method, did not show any distortion of the crystalline lattice in the area of the plate not disturbed during the opening of the tube and the preparation for X-ray investigation.
I wish to express my gratitude to Professor L. Sosnowski for his interest in this work and helpful remarks.
References 1) Z. Dziuba Acta Phys. Pol. 26 (1964) 897. 2) E. Cruceanu, 9 (1964) 537. D. Niculescu and A. Wanku, Kristallografiya 3) A. Mycielski and R. R. Galazka, in: Ninth Intern. Conf. on the Physics of Semiconductors, Vol. 2, Moscow, 1968, p. 875 4) E. Cruceanu, D. Niculescu, N. Nistor, I. Stamatescu and S. Jonescu-Buzer, Fiz. Tverd. Tela 7 (1965) 1808. 5) M. Schneider, Compt. Rend. B 268 (1969) 564. 6) R. T. Delves and B. Levis, J. Phys. Chem. Sol. 24 (1963) 549. 7) J. Litwin, unpublished data.
THE LIQULDUS CURVE AND CRYSTAL GROWTH IN THE Hg:Te SYSTEM
E. Z. DZIUBA Institute of Physics, Polish Academy of Sciences, Hoza 69, Warsaw, Poland
Received 19 December 1969; revised manuscript received 24 August 1970
The liquidus curve for the mercury telluride binary system is given for atomic concentrations of tellurium from 0.1% to 12°c.The form of the crystal which has been obtained from the solution depends on its concentration.
Semiconducting compounds can be crystallized using solutions of its components in different solvents by controlling the temperature or pressure dependence of the solubility of its components. Good quality crystals can be grown in forms of plates, needles and bulk. Mercury telluride is one of A2B6 semiconducting compounds which has a zinc blende lattice. Crystals of this material have been obtained by Bridgman method’) 2) and and in recent times also using sublimation solution3 5) methods. Theby best quality of the mercury telluride crystals was obtained by using the solution method, Various mixtures of three times destilled Hg and zone refined Te have been introduced in a glass tube of approximately 10 mm in diameter and 100 mm in length and connected to a vacuum system through a (a)
Fig. 1.
(b)
cooling-tube. Before the sealing off’), the tube was heated to remove gases dissolved in the liquid mercury and evacuated to 10 ~Torr. The tube, prepared in this way, retains a vacuum better than 10 2 Torr. Crystallization occurs during the lowering of the temperature with a rate of cooling of 0.5 C/hr, using a solution with a concentration of Te up to x 0.02 (ref.whole 3). Asurface single of crystal of aboutConcentrations 50 jim thick covers the the solution. larger than x = 0.03 Te did not produce one large plate single crystal, even at cooling rates lower than 0.5 °C/h.Instead, a large number of monocrystals having an irregular terrace form with dimentions up to 1 cm2 are obtained3’4) (fig. 2). An explanation for the growth of thin plate crystals, is given by analysing the liquidus of the Hg-Te system (a)
Mercury telluride crystals obtained from the solution ha~ing(a) high and (b) low concentrations ofTe.
221
222
E. Z. DZIUBA
There are no difficulties in removing the crystals from the tube when the crystals have terrace forms. The liquid mercury is removed from the surface of the crystal by etching in HNO3 and in a solution of 1 % Br in methyl alcohol. It is difficult to remove the SOpm thin plates from the tube. Before opening it is necessary to put the tube into a bath with the mercury. If the levels of the mercury inside and outside of the tube are the same, it is possible to open the glass tube without turbulent movement of the mercury in the tube. xz,’mci~
Fig. 2.
10
The liquidus curve in Hg:Te binary system.
shown in fig. 26). A change of the slope, of the liquidus line occurs at x = 0.03. The probability of the growth of many crystals during the crystallization process is larger when the solution has a high concentration of tellurium, whereas low concentrations favor the growth of a single crystal on the surface. The quality of the thin plate crystals grown from 7). the 0.02 Te solution of Te was investigated by Litwin X-ray analysis df a crystal, using the pseudo-Kossel lines method, did not show any distortion of the crystalline lattice in the area of the plate not disturbed during the opening of the tube and the preparation for X-ray investigation.
I wish to express my gratitude to Professor L. Sosnowski for his interest in this work and helpful remarks.
References 1) Z. Dziuba Acta Phys. Pol. 26 (1964) 897. 2) E. Cruceanu, 9 (1964) 537. D. Niculescu and A. Wanku, Kristallografiya 3) A. Mycielski and R. R. Galazka, in: Ninth Intern. Conf. on the Physics of Semiconductors, Vol. 2, Moscow, 1968, p. 875 4) E. Cruceanu, D. Niculescu, N. Nistor, I. Stamatescu and S. Jonescu-Buzer, Fiz. Tverd. Tela 7 (1965) 1808. 5) M. Schneider, Compt. Rend. B 268 (1969) 564. 6) R. T. Delves and B. Levis, J. Phys. Chem. Sol. 24 (1963) 549. 7) J. Litwin, unpublished data.