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Chemical transport reactions during crystal growth of PbTe and PbSe via vapour phase influenced by AgI.

Gasphasen-Transportreaktion während der Kristallzucht von PbTe und PbSe beeinflußt durch AgI
: Stöber, D.; Hildmann, B.O.; Böttner, H.; Schelb, S.; Binnewies, M.; Bachem, K.H.


Journal of Crystal Growth 121 (1992), pp.656-664 : Abb.,Lit.
ISSN: 0022-0248
Journal Article
Fraunhofer IPM ()
crystal growth; Halbleiter; IV-VI compound; IV-VI-Verbindung; Kristallzucht; semiconductor; transport reaction; Transportreaktion

Large and highly perfect PbSe and PbTe single crystals are grown in closed ampoules by chemical transport via vapour phase in an iodine atmosphere. The growth rates increase by a factor of four and the growth temperature is lowered by 130 K compared to the growth method without iodine as transport agent. Small amounts of silver iodine are used to adjust the iodine vapour pressure at the growth temperature within the closed ampoule. Steady-state Knudsen cell mass spectrometric analyses reveal the species in the vapour phase predominantly involved in the chemical transport reactions. At the actual growth temperature T is equal to 970 K the composition of the vapour contains mainly PbIsub2 and Tesub2 or PbIsub2 and Sesub2 species. The PbIsub2 vapour pressure depends sensitively on the iodine pressure. The thermal decomposition of AgI adjusts the PbIsub2 pressure below its saturation vapour pressure and no condensation of PbIsub2 occurs. The condensation of PbIsub2 would inhibit an effecti ve growth process by covering the surface of the growing crystal. The pressure and temperature region for the PbTe-AgI and PbSe-Agl crystal growth systems is calculated.