Journal of the Japanese Association for Crystal Growth
Online ISSN : 2187-8366
Print ISSN : 0385-6275
ISSN-L : 0385-6275
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Special Issue : Temperature Field and its Gradient in Bulk Crystal Growth from Melt
Preface
Review
  • Toshinori Taishi
    2020 Volume 47 Issue 2 47-2-01
    Published: 2020
    Released: August 04, 2020
    JOURNALS RESTRICTED ACCESS

      In this paper, several experimental results of temperature measurement in the melt and the crystal using thermocouples during the bulk crystal growth are exhibited. In order to investigate the relationship between grown-in defects, growth rate and temperature gradient in Czochralski silicon crystal growth, the temperature and its gradient in the melt and the crystal at the center were measured using thermocouples. Silicon crystals 70 mm in diameter were grown with such temperature measurement. It was found that temperature gradient in both the melt and the crystal increased with increasing pulling rate of the crystal. The balance equation of heat transportation was well satisfied by temperature gradients directly obtained using a specific thermocouple of the differential type. Finally, a meaning of temperature measurement in the crystal during the growth is described.

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  • Koun Shirai
    2020 Volume 47 Issue 2 47-2-02
    Published: 2020
    Released: August 04, 2020
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      In crystal growth, the mass transfer from the liquid/solid interface influences the gradient of the temperature at the interface. A one-dimensional analysis demonstrates the effect of the mass transfer on the pulling-rate dependence on the temperature gradient. This is in a qualitative agreement with the observed data. However, inconsistency with the heat balance remains.

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  • Shin-ichi Nishizawa, Yoshiji Miyamura, Hirofumi Harada
    2020 Volume 47 Issue 2 47-2-03
    Published: 2020
    Released: August 04, 2020
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      Temperature distribution in the growing crystal is the most important parameter that determines the grown-in-defects, growth rate, etc. In general understanding, and some experiments showed that higher growth rate leads to the larger thermal gradient. But other reports showed that temperature gradient in growing crystal decreases as increasing the growth rate. In order to make clear the reason of this discrepancy, the effects of growth rate on the temperature distribution in growing crystal were analyzed by numerical modeling. As increasing the growth rate, the shape of melt/crystal interface becomes more convex toward the crystal. Along the center axis, conductive heat transfer is dominant. Then convex interface shape and larger thermal gradient were obtained. In the growing crystal near the triple points, because of convex interface shape, heat transfer in radial direction, and radiative heat transfer from growing crystal surface becomes important. Then smaller thermal gradient along surface was obtained..

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  • Kozo Fujiwara
    2020 Volume 47 Issue 2 47-2-04
    Published: 2020
    Released: August 04, 2020
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      Grain growth behaviors at a crystal/melt interface of multi-crystalline silicon are introduced in this article. It will be explained how the understanding of this phenomena has been progressed to date. The experimental results by in situ observations will be presented. The importance of growth kinetics at a grain boundary groove on the grain growth behavior will be shown.

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  • Satoshi Uda, Tomohiro Kawase, Toshinori Taishi
    2020 Volume 47 Issue 2 47-2-05
    Published: 2020
    Released: August 04, 2020
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      Two topics in oxide and compound semiconductor bulk crystal growth about relationship between crystal quality and temperature gradient near the growth interface are introduced. In oxide crystal growth, the occurrence of cracking during growth of an oxide crystal is associated with the polycrystallization during the shoulder formation. The effect of temperature gradient near the interface on polycrystallization shows an opposite manner between crystals grown from less viscous melt and those from highly viscous melt. A crystal fiber grown by LHPG or µ-PD method accompanies a large temperature gradient along vertical and radial directions, which induce an interface electric field modifying the transportation and partitioning of ionic species. In GaAs crystal growth, dislocations and lineages easily generate due to small critical resolved shear stress and thermal conductivity and large latent heat of fusion. Countermeasures for growing larger-scale GaAs crystals under precise control of temperature gradient and growth rate are proposed.

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  • Tomohiro Kawamura, Takefumi Iida, Reiko Ishikawa, Tatsuya Hitomi, Toru ...
    2020 Volume 47 Issue 2 47-2-06
    Published: 2020
    Released: August 04, 2020
    JOURNALS RESTRICTED ACCESS

      The origins of the unintentional formation of polycrystalline AlN during homoepitaxial growth of single-crystal AlN layers by hydride vapor phase epitaxy (HVPE) on single-crystal AlN substrates prepared by physical vapor transport (PVT) were investigated. The formation of polycrystalline AlN in the HVPE layer should be suppressed since it may cause malfunctions in devices such as AlGaN-based deep-UV light emitting devices. Using electron probe microanalysis (EPMA) or transmission electron microscopy (TEM), the polycrystals were found to originate from contamination due to byproducts of the reaction between the source gases, and also from crystallographic defects originating from the AlN substrate.

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Original Paper
  • Yuki MAKINOSE, Toru OSAKO, Hidetoshi MIYAZAKI
    2020 Volume 47 Issue 2 47-2-07
    Published: 2020
    Released: August 04, 2020
    JOURNALS RESTRICTED ACCESS

      In this study, SnO particles were synthesized by the hydrothermal method using NH3 or NaOH as alkaline solutions with various pH values. Cross structures were formed by using NH3 with pH values of 9, 10, and 11. Agglomerated plates and blocks were formed using NaOH with pH ranges of 9-10 and 11-12, respectively. The resulting crosses, plates, and blocks with SnO particles were observed to comprise an exposed {001} plane with a plate-like structure, whenever NaOH or NH3 was used. Further, NH3 facilitated the SnO growth due to its OH ion buffering ability. The addition of NaOH caused a rapid growth of SnO particles when the reaction solution had a high pH that ranged from 11 to 12. Cross structures were also formed by using a mixed solution of NH3 and NaOH with pH of 10. Moreover, NH3 was observed to promote the formation of a cross structure.

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