Vapor-Phase Growth of Bulk Crystals of Cadmium Telluride and Cadmium Zinc Telluride on Gallium Arsenide Seeds

Abstract

The growth of large-area bulk crystals of cadmium telluride and cadmium zinc telluride has been demonstrated using the combination of a novel physical vapor transport growth system and heteroepitaxial seeding on GaAs wafers. X-ray diffraction studies show the resulting material to be of extremely high quality despite the large lattice mismatch between the seed and the grown crystal. This process should provide a reliable growth route for large-area large-volume single-crystal boules of cadmium telluride and cadmium zinc telluride.

Characterisation of vapour grown CdZnTe crystals using synchrotron X-ray topography

“…Bulk CdZnTe crystals were grown by the Multi-Tube Physical Vapour Transport (MTPVT) method [16,17]. This growth method consists of three quartz tubes connected with each other via a quartz cross-member, thus forming a 'U' shape design ( Fig.…”

“…Further details of the MTPVT method can be found in Refs. [16,17]. Grown boules are 50 mm in diameter and about 10 mm in thickness with a zinc concentration of around 5%.…”

“…Furthermore, vapour phase crystals can be grown without contact with the ampoule walls, significantly reducing stress during cooling down [14]. Results on the structural (X-ray diffraction), optical (IR transmission, photoluminescence) and electrical (resistivity, charge transport) properties of vapour grown CdZnTe have been previously presented in other work [15][16][17][18].…”

Twinning in vapour-grown, large volume Cd1−Zn Te crystals

“…However, past attempts at vapour growth have been frustrated by the inability to control independently the source and seed temperatures, and the transport rate. We have successfully grown CdTe [14] and CZT crystals [15,11] up to 100mm diameter on GaAs substrates, using a multi-tube physical vapour transport (MTPVT) technique [16,17]. The key feature of the growth system is that the temperatures of source and seed are thermally decoupled by use of independent vertical furnaces which are parallel, separated horizontally and interconnected by a horizontal, heated, transport tube to avoid any line of sight, and thus radiative thermal coupling, between source and seed.…”

“…In the case of the binary CdTe, such twinning may be observed at any stage from nucleation to the bulk growth phase. Despite this, untwinned CdTe boules up to 8 mm thick have been grown and have been shown to have high structural perfection [14]. In contrast, Cd 1-x Zn x Te grown on (211)B CdTe buffer layers invariably twins mainly but not entirely to…”