Double Crucible Research Articles

Application of Double Crucible in Cz Si Crystal Growth

The numerical modeling of melt flow, heat transfer and impurity (phosphorus) diffusion in the double crucible of "Redmet-90M" Cz puller was carried out in an application to a 200 mm diameter Si single crystal growth. The double crucible consists of two coaxial crucibles having different sizes: 490 mm (external) and 300 mm (internal) inner diameters. The bottom of internal crucible has a central hole of Do = 6 and 12 mm diameter for melt inflow from the external crucible. During crystal pulling the granulated Si was added in the external crucible and a melt of the internal crucible was doped by phosphorus. Three-dimensional features of a rotating melt flow affecting on heat transfer and impurity diffusion in the internal crucible were analyzed. In particular, the melt precession and thermal asymmetry near the liquid-solid interface (LSI) in the internal crucible are discussed. It is shown that a significant phosphorus losses caused by its evaporation from a melt surface may be compensated by additional phosphorus doping in the internal crucible.

A Study of Convection, Striations and Interface Shape in InP Crystals Grown by the Double‐Crucible LEC Technique

AbstractA doublecrucible (DC) Czochralski setup has been used for the pulling of semi‐insulating Fe‐doped InP. The level of the Fe‐doped melt in the growth crucible is replanished with the undoped InP from the reservoir crucible. In this way, since the distribution coefficient of iron is very small (about 0.001), the Fe concentration in the growth crucible is virtually unchanged during the pulling so that the axial Fe concentration is much more uniform than in standard LEC crystals. The use of two concentric crucibles has great implications in terms of convective flows, stability of the melt temperature and interface shape. In this paper we report the results of a study on striations and structural defects in InP grown from a double‐crucible LEC arrangement. A dimensionless relationship for correlating striation features with melt motions is also proposed.

Constant temperature LEC growth of InGaAs ternary bulk crystals using the double crucible method

A double crucible method was developed to improve the controllability of the supply of GaAs source element to the growth melt close to the growing interface for the liquid encapsulated Czochralski (LEC) technique. The double crucible has growth melt and source melt zones which are separated by a cylindrical wall with a slit. The GaAs solute element is controllably supplied from the source melt zone. The GaAs constituent is supplied to the source melt by immersing a GaAs source rod in the source melt zone. An In 0.07Ga 0.93As uniform crystal can be successfully grown using this method. The length and diameter of the crystal are about 5 and 1.5 cm, respectively.

Determination of Ultra Low Contents of Oxygen in High Purity Iron

Determination of trace oxygen in high purity iron was studied using a LECO TC-436 oxygen/nitrogen determinator. Examined were oxygen blanks due to helium carrier gas, apparatus and graphite crucibles. The blank due to helium carrier gas was reduced and stabilized by using a gas refining system usable for twelve months or more without repack of reagents. The blank in the apparatus was reduced and stabilized by removing the water adsorbed on the wall of a carrier gas tube. The blank in a double graphite crucible was significantly lowered by using an outer crucible deoxidized with silicon at 2373 K and an inner one degassed at 2573 K for 120 s. As a result of these improvements, the blank value for oxygen analysis using the LECO determinator decreased to less than 0.01 mass ppm O

Fibre bundle comprising nineteen optical fibres drawn from the double crucible

A new technique of simultaneously drawing nineteen optical fibres from a double crucible is presented. Rotation of the crucible around its axis allows the fibres to be stranded during the drawing process. The fibres coated in-line with a silicone resin showed good cross-sectional symmetry and optical losses similar to those obtained in the single-fibre drawing process.

A simple method for thennoanalysis of evolved gases

Thermoanalytical processes involving the splitting-off of ammonia, water, halogens, inorganic acids or acid anhydrides can be simply observed by using a specimen-holder in which specific reactions with the decomposition products can be induced. A special glass or quartz double crucible can be used for this purpose; the products arising in the lower part of the crucible can be oxidized selectively with reagents placed in the upper part, or can be bound or transformed into other compounds. This double crucible is also suitable for studying reactions taking place between solid and gaseous substances.

Evaporation Characteristics of Iron-Nickel Alloys

The evaporation characteristics of iron-nickel alloys at high temperature in high vacuum were studied in the ranges of composition from 10 to 90 atomic percent of iron and of temperature between 1400°C and 1800°C. The evaporator was the double crucible of BeO for practical use with the similar structure to that of Knudsen Is cell (see Fig. 2). The compositions of samples deposited continuously on each individual glass substrate one by one were determined by chemical microanalysis (using spectrophoto metric method). By plotting the contents of either iron or nickel in deposits against evaporation time and extrapolating them to the origin of time scale, the composition of deposit corresponding to the original composition of alloy could be obtained. Then, basing on these data, so-called x-y curves and values of relative volatilities, representing the fractionation power, were obtained for Fe-Ni systems. Such results are discussed and the behaviour of mass transportation in molten alloy on the progression of evaporation in the crucible is explained with a model.