Abstract

Mass transport rate and composition of the transported material as a function of different process parameters like temperature, undercooling, inert gas pressure, and the source compactness for different PbTe_1-xSe_x compositions were studied. With proper preparation procedures mass transport rates suitable for growth at the rate of 0.5–1 mm/h were obtained. Different composition non-uniformities in the deposited material were observed. Due to deviation of the PbTe–PbSe solid solution from ideality, congruent mass transport of the material takes place around X=0.3. For other compositions an improved and even good uniformity can be achieved when a solid, pre-melted source material is used.

Author Keywords: PbSeTe; Vapor growth; IV–VI; PVT; Residual gas

PACS classification codes: 81.05.Hd; 81.10.Bk; 81.20.Ym

Article Outline

1. Introduction

2. Theoretical model

3. Experimental procedures

4. Results and discussion

4.1. Equilibrium partial pressures

4.2. Residual gas pressures and mass transport rates

4.3. Concentration profiles

4.3.1. Effect of the source composition

4.3.2. Effect of the source temperature and undercooling

4.3.3. Effect of the source density and growth rate

5. Summary and conclusions

Acknowledgements

References

(8K)
Fig. 1. Equilibrium partial pressures over PbTe (solid lines), PbSe (dashed lines), and elemental Pb (dotted line).

(6K)
Fig. 2. Theoretical and experimental mass flux as a function of crystal composition. Full circles () standard preparation and pre-treatment of the source material (procedure "a"); open triangles () 30 min bake-out under dynamic vacuum (procedure "b"), coarse source (0.3–0.5 mm grains); full triangle () procedure "b", finely ground source (<0.1 mm); open square () source contaminated with oxygen.

(5K)
Fig. 3. Activity coefficients of PbTe and PbSe in PbTe_1-xSe_x as a function of composition.

(8K)
Fig. 4. Theoretically calculated dependence of the composition of the crystal and that of the source for the reference (T(source)=850°C, T=10°C , 0.5 Torr of carbon monoxide) and other conditions.

(10K)
Fig. 5. Axial composition profiles in the crystals. Dashed lines, initial source compositions. Source materials: (o) finely ground (<0.1 mm) powder; (.) non-pre-synthesized mixture of PbTe and PbSe powders; () coarse (0.5–1 mm) material. For clarity, only every second experimental point is shown.

(11K)
Fig. 6. Axial composition profiles in the crystals grown from X=0.10 to 0.50 powdered sources under different temperature and undercooling conditions. For clarity, the experimental points are not shown.

(7K)
Fig. 7. Axial composition profiles in the crystals grown from X=0.10 sources. Solid symbols, powdered source under low (, 0.5 Torr of carbon monoxide) and high (, 4 Torr of argon) inert gas pressure conditions; open symbols, solid pre-melted source. For clarity, only every fifth experimental point is shown.

Table 1. Residual gas pressures generated in growth ampoulesa (<1K)

References

1. W. Palosz. J. Crystal Growth 216 (2000), p. 273. SummaryPlus | Full Text + Links | PDF (177 K)

2. H. Maier, D.R. Daniel and H. Preier. J. Crystal Growth 35 (1976), p. 121. Abstract

3. J. Zoutendyk and W. Akutagawa. J. Crystal Growth 56 (1982), p. 245. Abstract

4. H. Preier, R. Herkert and H. Pfeiffer. J. Crystal Growth 22 (1974), p. 153. Abstract

5. I. Kasai, D.R. Dniel, H. Maier and H.–D. Wurzinger. J. Crystal Growth 23 (1974), p. 201. Abstract

6. S.G. Parker, J.E. Pinelli and R.E. Johnson. J. Elect. Mater. 3 (1974), p. 731. Abstract-Compendex | Abstract-INSPEC  

7. Z. Golacki, M. Gorska, T. Warminski and A. Szczerbakow. J. Crystal Growth 74 (1986), p. 129. Abstract

8. T.V. Saunina, D.B. Chesnokova and D.A. Jaskov. J. Crystal Growth 71 (1985), p. 75. Abstract

9. W. W. Scanlon, in: F. Seitz, D. Turnbull (Eds.), Solid State Physics, Academic Press, New York, 1959.

10. A. Katzir, R. Rosman, Y. Shani, K. H. Bachem, H. Bottner, H. M. Preier, in: P. K. Cheo (Eds.), Handbook of Solid State Lasers, Marcel Dekker, New York, 1989.

11. H.L. Toor. A. I. Ch. E. J. 3 (1957), p. 198.

12. R.F. Brebrick and A.J. Strauss. J. Chem. Phys. 40 (1964), p. 3230.

13. R. Hultgren (Ed.), Selected Values of the Thermodynamic Properties of the Elements, American Society for Metals, Cleveland, OH, 1973.

14. I. Barin and O. Knacke. Thermochemical Properties of Inorganic Substances, Springer, Berlin (1974).

15. I. Barin, O. Knacke and I. Kubaschewski. Thermochemical Properties of Inorganic Substances, Supplement, Springer, Berlin (1977).

16. V.V. Sokolov, V.A. Dolgikh, A.S. Pashinkin and A.V. Novoselova. Inorg. Mater. 5 (1969), p. 232.

17. R. A. Svehla, NASA Technical Report R-132, 1962.

18. H. Wiedemeier, D. Chandra and F.C. Klaessig. J. Crystal Growth 51 (1981), p. 345. Abstract

19. W. Palosz, J. Jpn. Soc. Microgravity Appl. 15 (Suppl. II) (1998) 454.

20. W. Palosz, S.L. Lehoczky and F.R. Szofran. J. Crystal Growth 148 (1995), p. 49. SummaryPlus | Full Text + Links | PDF (418 K)

21. W. Palosz, F.R. Szofran and S.L. Lehoczky. J. Crystal Growth 148 (1995), p. 56. SummaryPlus | Full Text + Links | PDF (522 K)

¹ Universities Space Research Association, Staff Scientist.

² Currently with Federal Data Corporation, NASA-GRC, Cleveland, OH, USA.

Corresponding author. Tel.: +1-256-544-1272; fax: +1-256-544-6762; email: witold.palosz@msfc.nasa.gov