“…This seeming contradiction must be explained on the basis of the applicability range of Klosse's model [23]. As already pointed out elsewhere [24], with iodine concentrations below certain values, the transport rate is likely to be governed by the rate of heterogeneous reaction of source vaporisation, rather than by diffusion, regardless of the temperature gradient applied. We believe that this is most probably the case for test No.…”
Section: Discussionmentioning
confidence: 93%
“…The interested reader is referred to Klosse's work [23] for a detailed treatment of such aspects. For example, for simple systems it is known that crystallographic perfection is favoured under diffusion-limited transport rate, when nucleation density is minimized [24]. However, due to the pentanary nature of our system, the formation of compositionally well-defined sinks is subject to the risk of incongruent transport [33].…”
Section: Introductionmentioning
confidence: 96%
“…The importance of fluid dynamics in determining the right growth conditions in such systems is well described by the literature [22][23][24][25][26][27][28][29][30][31][32]. The CVT crystal grower will often encounter dimensionless numbers such as the Grashof, Schmidt, Prandtl and Rayleigh numbers that serve for the description of the system, especially with regard to diffusion and convection.…”
Single crystals of Cu 2 ZnSnS 4 have been produced within sealed quartz ampoules via the chemical vapour transport technique using I 2 as the transporting agent. The effects of temperature gradient and I 2 load on the crystal habit and composition are considered. Crystals have been analysed with XRD, SEM, and TEM for compositional and structural uniformities at both microscopic and nanoscopic levels. The synthesized crystals have suitable (I 2 -load dependent) properties and are useful for further solar absorber structural and physical characterizations. A new chemical vapour transport method based on longitudinally isothermal treatments is attempted. Based on a proposed simplistic mechanism of crystal growth, conditions for crystal enlargement with the new method are envisaged.
“…This seeming contradiction must be explained on the basis of the applicability range of Klosse's model [23]. As already pointed out elsewhere [24], with iodine concentrations below certain values, the transport rate is likely to be governed by the rate of heterogeneous reaction of source vaporisation, rather than by diffusion, regardless of the temperature gradient applied. We believe that this is most probably the case for test No.…”
Section: Discussionmentioning
confidence: 93%
“…The interested reader is referred to Klosse's work [23] for a detailed treatment of such aspects. For example, for simple systems it is known that crystallographic perfection is favoured under diffusion-limited transport rate, when nucleation density is minimized [24]. However, due to the pentanary nature of our system, the formation of compositionally well-defined sinks is subject to the risk of incongruent transport [33].…”
Section: Introductionmentioning
confidence: 96%
“…The importance of fluid dynamics in determining the right growth conditions in such systems is well described by the literature [22][23][24][25][26][27][28][29][30][31][32]. The CVT crystal grower will often encounter dimensionless numbers such as the Grashof, Schmidt, Prandtl and Rayleigh numbers that serve for the description of the system, especially with regard to diffusion and convection.…”
Single crystals of Cu 2 ZnSnS 4 have been produced within sealed quartz ampoules via the chemical vapour transport technique using I 2 as the transporting agent. The effects of temperature gradient and I 2 load on the crystal habit and composition are considered. Crystals have been analysed with XRD, SEM, and TEM for compositional and structural uniformities at both microscopic and nanoscopic levels. The synthesized crystals have suitable (I 2 -load dependent) properties and are useful for further solar absorber structural and physical characterizations. A new chemical vapour transport method based on longitudinally isothermal treatments is attempted. Based on a proposed simplistic mechanism of crystal growth, conditions for crystal enlargement with the new method are envisaged.
“…CVT-grown ZnSe crystals contain iodine and have strong SA emission, which is favorable for white LED fabrication. However, it is difficult to grow large-diameter ZnSe single crystals by the CVT method, since convective mass transport deteriorates the stability of surface morphology [7]. Several years ago, rotational CVT (R-CVT), which comprises the rotation of the horizontal growth ampoule with a constant frequency, was developed to facilitate the growth of 1 in.…”
Large ZnSe single crystals with a diameter of 30 mm and a thickness of 25 mm were successfully obtained by the rotational chemical vapor transport (R-CVT) using iodine as a transport agent, which comprises the rotation of the horizontal growth ampoule with a constant frequency. Two-step annealing was developed to ensure the stable growth of the epitaxial layer by MBE on the obtained ZnSe substrates in addition to electrical conductivity. It was demonstrated that the optical properties of the CVT-grown ZnSe, photoluminescence and excitation of SA emission, was superior for the fabrication of white LEDs. r 2004 Elsevier B.V. All rights reserved.
“…7, and could be caused possibly by thermal convection [19,23,28,30,33,50,53,57,65,81]. Upon opening the ampoule in that case, the total pressure at room temperature appeared to be higher than one bar by reason of unknown vapor.…”
Section: Comparison Between Theory and Experimentsmentioning
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