CONTEXT

Segregation of chemical species during solidification of alloys is a well known problem which leads to defects in the material and is largely prejudicial to electronic properties of semi conductors or optical properties of lasers and scintillators. Moreover composition variations lead to microstructure defects detrimental to the growth of single crystals and in some cases leading to breakdown of the samples. There is a need for a simple process aiming at producing highly alloyed materials without  cracks in the crystal and showing high radial and longitudinal homogeneity with an acceptable cristallisation  speed (mm/h).

The well known  « Bridgman » method does not fulfill these requirements (cracks and lack of homogeneity)

TECHNICAL DESCRIPTION

In the process as proposed here a conductive material is melt  in a crucible.The temperature of the molten material is slowly decreased so that a Liquid-Solid (LS) interface is created  and the flatness of the SL interface is controlled through the control of the temperature of a piston maintained above the interface. The melt material is stirred by alternative electromagnetic forces during all the process.

BENEFITS

Faster growth rate/uniform alloy composition (radial and longitudinal) and crystal homogeneity / production of conductive materials / highly alloyed materials / The process may be applied to any conductive material such as

* semiconductors (germanium and silicium binary alloys/ III-V ternary alloys based on antimony – GaSb, AlSb, InSb-, arsenides -GaAs  InAs – or phospides – GaP, InP-, ternary II-IV alloys based on tellurides -CdTe, ZnTe, HgTe- or  selenides – CdSe , ZnSe-, silicium).
* metallic alloys
* glasses
* oxides or halide crystals if they are electrically condicting in liquid state

INDUSTRIAL APPLICATIONS

* micro-electronics (Ge and Si alloys)
* high-speed electronics and optoelectronics (GaSb, AlSb , InSb, GaAs,  InAs, GaP, In…)
*sensors /detectors for all wavelengths: gamma, X, UV, visible or IR (CdTe, ZnTe, HgTe, CdSe, ZnSe)
* Photovoltaic application by melting and refining of Silicon from lower purity and hence lower cost
* technical glasses for optronics.

For further information, please contact us (Ref 01707-01)