Diffusion-Controlled Dopant Transport During Magnetically-Stabilized Liquid-Encapsulated Czochralski Growth of Compound Semiconductor Crystals

2001 ◽  
Vol 123 (4) ◽  
pp. 893-898 ◽  
Author(s):  
Joseph L. Morton ◽  
Nancy Ma ◽  
David F. Bliss ◽  
George G. Bryant
Keyword(s):  
Magnetic Field ◽  
Optical Properties ◽  
Dopant Concentration ◽  
Axial Magnetic Field ◽  
Compound Semiconductor ◽  
Czochralski Growth ◽  
Semiconductor Crystal ◽  
Semiconductor Crystals ◽  
Diffusion Controlled ◽  
Single Compound

During the magnetically-stabilized liquid-encapsulated Czochralski (MLEC) process, a single compound semiconductor crystal is grown by the solidification of an initially molten semiconductor (melt) contained in a crucible. The melt is doped with an element in order to vary the electrical and/or optical properties of the crystal. During growth, the so-called melt-depletion flow caused by the opposing relative velocities of the encapsulant-melt interface and the crystal-melt interface can be controlled with an externally applied magnetic field. The convective dopant transport during growth driven by this melt motion produces nonuniformities of the dopant concentration in both the melt and the crystal. This paper presents a model for the unsteady transport of a dopant during the MLEC process with an axial magnetic field. Dopant distributions in the crystal and in the melt at several different stages during growth are presented.

Segregation During Magnetically-Stabilized Liquid-Encapsulated Growth of Compound Semiconductor Crystals

2000 ◽  
Author(s):  
Nancy Ma ◽  
David F. Bliss ◽  
George G. Bryant
Keyword(s):  
Magnetic Field ◽  
Optical Properties ◽  
Applied Magnetic Field ◽  
Dopant Concentration ◽  
Axial Magnetic Field ◽  
Compound Semiconductor ◽  
Semiconductor Crystal ◽  
Semiconductor Crystals ◽  
Single Compound ◽  
Relative Motions

Abstract During the magnetically-stabilized liquid-encapsulated Czochralski (MLEC) process, a single compound semiconductor crystal is grown by the solidification of an initially molten semiconductor (melt) contained in a crucible. The melt is doped with an element in order to vary the electrical and/or optical properties of the crystal. During growth, the so-called melt-depletion flow caused by the opposing relative motions of the encapsulant-melt interface and the crystal-melt interface can be controlled with an externally applied magnetic field. The convective dopant transport during growth driven by this melt motion produces non-uniformities of the dopant concentration in both the melt and the crystal. This paper presents a model for the unsteady transport of a dopant during the MLEC process with an axial magnetic field. Dopant distributions in the crystal and in the melt at several different stages during growth are presented.

Thermoelectrically Driven Melt Motion During Floating Zone Crystal Growth With an Axial Magnetic Field

1998 ◽  
Vol 120 (4) ◽  
pp. 839-843 ◽  
Author(s):  
Y. Y. Khine ◽  
J. S. Walker
Keyword(s):  
Magnetic Field ◽  
Crystal Growth ◽  
Axial Magnetic Field ◽  
Azimuthal Velocity ◽  
Liquid Interfaces ◽  
Floating Zone ◽  
Semiconductor Crystal ◽  
Electrical Conductivities ◽  
Solid Liquid ◽  
Key Parameter

During semiconductor crystal growth with an externally applied magnetic field, thermoelectric currents may drive a melt circulation which affects the properties of the crystal. This paper treats a model problem for a floating zone process with a uniform axial magnetic field, with planar solid-liquid interfaces, with a cylindrical free surface, with a parabolic temperature variation along the crystal-melt interface, and with an isothermal feed rod-melt interface. The ratio of the electrical conductivities of the liquid and solid is a key parameter. The azimuthal velocity is much larger than the radial or axial velocity. There is radially outward flow near the crystal-melt interface which should be beneficial for the mass transport of dopants and species.

Forced Convection During Liquid Encapsulated Crystal Growth With an Axial Magnetic Field

1998 ◽  
Vol 120 (4) ◽  
pp. 844-850 ◽  
Author(s):  
Nancy Ma ◽  
John Walker ◽  
David Bliss ◽  
George Bryant
Keyword(s):  
Magnetic Field ◽  
Field Strength ◽  
Forced Convection ◽  
Magnetic Field Strength ◽  
Axial Magnetic Field ◽  
Vertical Wall ◽  
Czochralski Growth ◽  
Centripetal Acceleration ◽  
Radial Gap ◽  
The Magnetic Field

This paper treats the forced convection, which is produced by the rotation of the crystal about its vertical centerline during the liquid-encapsulated Czochralski or Kyropoulos growth of compound semiconductor crystals, with a uniform vertical magnetic field. The model assumes that the magnetic field strength is sufficiently large that convective heat transfer and all inertial effects except the centripetal acceleration are negligible. With the liquid encapsulant in the radial gap between the outside surface of the crystal and the vertical wall of the crucible, the forced convection is fundamentally different from that with a free surface between the crystal and crucible for the Czochralski growth of silicon crystals. Again unlike the case for silicon growth, the forced convection for the actual nonzero electrical conductivity of an indium-phosphide crystal is virtually identical to that for an electrically insulating crystal. The electromagnetic damping of the forced convection is stronger than that of the buoyant convection. In order to maintain a given balance between the forced and buoyant convections, the angular velocity of the crystal must be increased as the magnetic field strength is increased.

scholarly journals Growth of Binary Alloyed Semiconductor Crystals by the Vertical Bridgman-Stockbarger Process with a Strong Magnetic Field

2005 ◽  
Vol 127 (3) ◽  
pp. 523-528 ◽  
Author(s):  
Stephen J. LaPointe ◽  
Nancy Ma ◽  
D. W. Mueller
Keyword(s):  
Magnetic Field ◽  
Axial Magnetic Field ◽  
Convective Transport ◽  
Transient Model ◽  
Buoyant Convection ◽  
Semiconductor Crystals ◽  
Thermally Driven ◽  
Vertical Bridgman ◽  
Compositional Variations ◽  
Alloyed Semiconductor

This paper presents a model for the unsteady species transport for the growth of alloyed semiconductor crystals during the vertical Bridgman-Stockbarger process with a steady axial magnetic field. During growth of alloyed semiconductors such as germanium-silicon (GeSi) and mercury-cadmium-telluride (HgCdTe), the solute’s concentration is not small, so that density differences in the melt are very large. These compositional variations drive compositionally driven buoyant convection, or solutal convection, in addition to thermally driven buoyant convection. These buoyant convections drive convective transport, which produces nonuniformities in the concentration in both the melt and the crystal. This transient model predicts the distribution of species in the entire crystal grown in a steady axial magnetic field. The present study presents results of concentration in the crystal and in the melt at several different stages during crystal growth.

Sign in / Sign up

Export Citation Format

Share Document